Primary Pulmonary NUT Midline Carcinoma: Clinical, Radiographic, and Pathologic Characterizations
2015; Elsevier BV; Volume: 10; Issue: 6 Linguagem: Inglês
10.1097/jto.0000000000000545
ISSN1556-1380
AutoresLynette M. Sholl, Mizuki Nishino, Saraswati Pokharel, Mari Mino–Kenudson, Christopher A. French, Pasi A. Jänne, Christopher S. Lathan,
Tópico(s)Peptidase Inhibition and Analysis
ResumoNUT midline carcinoma (NMC) is a poorly differentiated tumor typically driven by a t(15;19) rearrangement leading to a NUT fusion event. This rare and uniformly fatal tumor arises in multiple organ sites; however the clinical, radiographic, and pathologic characteristics of primary pulmonary NMC are poorly defined. We identified eight cases of primary pulmonary NMC in our consult practice over 4 years and, using a NUT immunohistochemistry screen, retrospectively identified one additional case from 166 (0.6%) consecutive in-house biopsies of lung carcinomas lacking glandular differentiation. Eight cases had available clinical and radiographic data and shared a remarkable degree of similarity. The median age at presentation was 30 (range 21–68). Six patients had little or no smoking history. All complained of 1 to 3 months of cough at presentation. Computed tomography scans showed a large, centrally located primary mass with confluent involvement of mediastinal lymph nodes, pleural disease, and sparing of the contralateral lung. Lytic bone metastases were common but brain metastases were absent in all cases. Pathologically, all cases showed primitive-appearing round to epitheloid cells growing in nests and sheets. All tumors expressed keratin, p63 or p40, and NUT protein. Eight cases had a fluorescence in situ hybridization-proven BRD4-NUT or BRD3-NUT rearrangement; one case was presumed to have a NUT-variant fusion event. Median overall survival was 2.2 months. Despite the rarity of primary pulmonary NMC, it is important to recognize this entity to counsel patients regarding outcome and to identify candidates for targeted BRD inhibitors currently in clinical trials. NUT midline carcinoma (NMC) is a poorly differentiated tumor typically driven by a t(15;19) rearrangement leading to a NUT fusion event. This rare and uniformly fatal tumor arises in multiple organ sites; however the clinical, radiographic, and pathologic characteristics of primary pulmonary NMC are poorly defined. We identified eight cases of primary pulmonary NMC in our consult practice over 4 years and, using a NUT immunohistochemistry screen, retrospectively identified one additional case from 166 (0.6%) consecutive in-house biopsies of lung carcinomas lacking glandular differentiation. Eight cases had available clinical and radiographic data and shared a remarkable degree of similarity. The median age at presentation was 30 (range 21–68). Six patients had little or no smoking history. All complained of 1 to 3 months of cough at presentation. Computed tomography scans showed a large, centrally located primary mass with confluent involvement of mediastinal lymph nodes, pleural disease, and sparing of the contralateral lung. Lytic bone metastases were common but brain metastases were absent in all cases. Pathologically, all cases showed primitive-appearing round to epitheloid cells growing in nests and sheets. All tumors expressed keratin, p63 or p40, and NUT protein. Eight cases had a fluorescence in situ hybridization-proven BRD4-NUT or BRD3-NUT rearrangement; one case was presumed to have a NUT-variant fusion event. Median overall survival was 2.2 months. Despite the rarity of primary pulmonary NMC, it is important to recognize this entity to counsel patients regarding outcome and to identify candidates for targeted BRD inhibitors currently in clinical trials. NUT midline carcinoma (NMC) is a highly aggressive tumor defined by a rearrangement involving the NUTM1 (Nut midline carcinoma, family member 1, NUT) gene on chromosome 15 and sharing some histopathologic features with squamous cell carcinomas. This rearrangement leads to the fusion of NUT to one of a number of possible partners including the bromodomain family members BRD3 or BRD4 or the methyltransferase, NSD3, leading to global epigenetic reprogramming and loss of cell differentiation.1French CA Rahman S Walsh EM et al.NSD3-NUT fusion oncoprotein in NUT midline carcinoma: Implications for a novel oncogenic mechanism.Cancer Discov. 2014; 4: 928-941Crossref PubMed Scopus (148) Google Scholar, 2French CA Pathogenesis of NUT midline carcinoma.Annu Rev Pathol. 2012; 7: 247-265Crossref PubMed Scopus (189) Google Scholar, 3French CA Miyoshi I Kubonishi I et al.BRD4-NUT fusion oncogene: A novel mechanism in aggressive carcinoma.Cancer Res. 2003; 63: 304-307PubMed Google Scholar, 4French CA Ramirez CL Kolmakova J et al.BRD-NUT oncoproteins: A family of closely related nuclear proteins that block epithelial differentiation and maintain the growth of carcinoma cells.Oncogene. 2008; 27: 2237-2242Crossref PubMed Scopus (309) Google Scholar, 5Schwartz BE Hofer MD Lemieux ME et al.Differentiation of NUT midline carcinoma by epigenomic reprogramming.Cancer Res. 2011; 71: 2686-2696Crossref PubMed Scopus (150) Google Scholar The tumor has been reported to arise in many sites, although the largest series suggest a predilection for the head and neck and mediastinum.6Stelow EB Bellizzi AM Taneja K et al.NUT rearrangement in undifferentiated carcinomas of the upper aerodigestive tract.Am J Surg Pathol. 2008; 32: 828-834Crossref PubMed Scopus (168) Google Scholar,7Evans AG French CA Cameron MJ et al.Pathologic characteristics of NUT midline carcinoma arising in the mediastinum.Am J Surg Pathol. 2012; 36: 1222-1227Crossref PubMed Scopus (84) Google Scholar NMC is extremely aggressive, with most cases presenting at an advanced stage and progressing rapidly to death. The estimated 2-year progression-free survival is 9%, based on studies incorporating all sites of disease.8Bauer DE Mitchell CM Strait KM et al.Clinicopathologic features and long-term outcomes of NUT midline carcinoma.Clin Cancer Res. 2012; 18: 5773-5779Crossref PubMed Scopus (254) Google Scholar Large series describing NMC in the lung are lacking, but existing literature suggests that primary pulmonary NMC is exceptionally rare. Tanaka et al.9Tanaka M Kato K Gomi K et al.NUT midline carcinoma: Report of 2 cases suggestive of pulmonary origin.Am J Surg Pathol. 2012; 36: 381-388Crossref PubMed Scopus (50) Google Scholar described only two cases of probable lung origin in a survey of 41 years of cases gathered from their institution, both in pediatric patients. Haruki et al.10Haruki N Kawaguchi KS Eichenberger S et al.Cloned fusion product from a rare t(15;19)(q13.2;p13.1) inhibit S phase in vitro.J Med Genet. 2005; 42: 558-564Crossref PubMed Scopus (36) Google Scholar derived the cell line HCC2429 from a metastatic lung carcinoma proven to contain the t(15;19) translocation, but were unable to identify any additional cases of NMC from a series of 128 lung carcinomas screened by fluorescence in situ hybridization (FISH) for this translocation. Pathologically, NMC is characterized by often monomorphic, primitive-appearing tumor cells frequently lacking the protein expression profiles characteristic of common carcinomas; however, cases can show squamous differentiation in the form of focal, abrupt keratinization and/or expression of high molecular weight cytokeratins and lineage-specific transcription factors, such as p63 and p40 (ΔNp63).7Evans AG French CA Cameron MJ et al.Pathologic characteristics of NUT midline carcinoma arising in the mediastinum.Am J Surg Pathol. 2012; 36: 1222-1227Crossref PubMed Scopus (84) Google Scholar,11Parikh SA French CA Costello BA et al.NUT midline carcinoma: An aggressive intrathoracic neoplasm.J Thorac Oncol. 2013; 8: 1335-1338Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar The undifferentiated nature of NMC leads to difficulty in morphologic recognition, and thus the differential diagnosis is broad, including poorly differentiated non–small-cell carcinoma, small-cell lung carcinoma, round cell sarcomas, and high grade lymphomas. An immunohistochemical antibody that specifically detects NUT protein overexpression can now facilitate rapid and cost–effective diagnosis of this rare tumor.12Haack H Johnson LA Fry CJ et al.Diagnosis of NUT midline carcinoma using a NUT-specific monoclonal antibody.Am J Surg Pathol. 2009; 33: 984-991Crossref PubMed Scopus (286) Google Scholar Experimental studies suggest that bromodomain inhibitors can drive terminal differentiation of NMC cells in culture and are thus a promising starting point for targeted inhibition of the BRD-NUT oncogenes.13Filippakopoulos P Qi J Picaud S et al.Selective inhibition of BET bromodomains.Nature. 2010; 468: 1067-1073Crossref PubMed Scopus (2847) Google Scholar Although rare, NMC is likely seen at a higher frequency at referral cancer centers, due to potentially ambiguous diagnostic features and unusually aggressive clinical course. We retrospectively examined our consult files for cases diagnosed as primary pulmonary NMC and herein describe the clinical, radiographic, and pathologic features of eight cases identified between 2010 and 2014. In an effort to better understand the frequency of the NMC diagnosis in a more routine setting, we retrospectively screened in-house biopsies performed for lung cancer within our institution between 2002 and 2010, a period before screening of poorly differentiated carcinomas for NUT overexpression by immunohistochemistry (IHC) became commonplace in our practice. As a result of these efforts, we demonstrate that primary pulmonary NMC, while rare, has highly characteristic symptomatic and radiographic features, pathology, and clinical course. Following approval by the Brigham and Women’s Hospital (BWH) Institutional Review Board (IRB), the pathology records of BWH were searched for the diagnosis “NMC” associated with a biopsy or surgical resection obtained from the thoracic cavity. Tumors thought to arise at extrapulmonary sites (these included head and neck, kidney, and anterior mediastinum) were excluded from review. A total of eight cases were identified; all initially presented at an outside hospital and were reviewed in consultation at DFCI/BWH between 2010 and 2014. Pathology slides for all cases with material still available in the BWH archives were re-reviewed. Details of patient history and clinical course were derived from the electronic medical record. The imaging studies at the time of diagnosis were reviewed by a board-certified radiologist with expertise in thoracic and oncologic imaging (M.N.). All but one patient had chest computed tomography (CT) scans available. Additional imaging studies, including 18F fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT, abdominal CT, head CT, bone scintigraphy, and brain magnetic resonance imaging (MRI), along with their radiology reports if available, were also reviewed if performed. Chest CT scans were evaluated focusing on the location and characteristics of the dominant lung lesion and associated lung parenchymal abnormalities, involvement of the contralateral lung, lymphadenopathy, pleural, and osseous abnormalities. PET/CT and other imaging studies were reviewed to identify the involvement of extrathoracic sites. The patient records at Dana Farber Cancer Institute (DFCI) were searched for all thoracic oncology patients with a biopsy performed for lung cancer at BWH between 2002 and 2010. The following diagnoses were included: poorly differentiated carcinoma, non–small-cell lung carcinoma (NSCLC), squamous cell carcinoma, and high grade neuroendocrine carcinoma and/or small cell lung carcinoma. Study cases were further restricted to those with adequate formalin-fixed paraffin-embedded (FFPE) tissue remaining in the archive. All specimens included in this study were obtained from patients who consented to correlative studies (DFCI IRB 02-180). Patient’s demographic and clinical features were derived from the medical record. IHC for NUT was performed on 4 μm thick FFPE sections. Slides underwent heat-induced epitope retrieval in citrate buffer and were incubated with primary rabbit monoclonal anti-NUT (clone C5261, 1:50; Cell Signaling Technology, Danvers, MA) and visualized using Bond Polymer Refine Detection (Leica Microsystems, Buffalo Grove, IL). IHC staining for NUT was interpreted by two or more pathologists (S.P., L.M.S., and C.A.F.). Positivity was defined as strong, speckled nuclear staining in greater than 50% of nuclei, as previously described.12Haack H Johnson LA Fry CJ et al.Diagnosis of NUT midline carcinoma using a NUT-specific monoclonal antibody.Am J Surg Pathol. 2009; 33: 984-991Crossref PubMed Scopus (286) Google Scholar Additional IHC staining for tumor markers was performed at the time of primary diagnosis according to standard clinical operating procedures in the BWH IHC laboratory. All tumors originally diagnosed as NSCLC were stained for this study with thyroid transcription factor-1 (TTF-1; M3575, 1:300; DAKO, Carpinteria, CA) and p40 (PC373; 1:800; EMD Millipore, Billerica, MA). For both stains, antigen retrieval was carried out with citrate buffer in a pressure cooker. Chromosomal translocation of the NUT gene locus was performed by FISH in NUT-IHC positive cases as previously described.14French CA Kutok JL Faquin WC et al.Midline carcinoma of children and young adults with NUT rearrangement.J Clin Oncol. 2004; 22: 4135-4139Crossref PubMed Scopus (293) Google Scholar Dual-color split-apart FISH assays were carried out on 4-μm-thick FFPE tissue sections. BRD4 on 19p13.1 was probed using telomeric tandem bacterial artificial chromosome (BAC) clones RP11-319o10 and RP11-681d10 (green) and centromeric BAC clones RP11-207i16 and CTD-3055m5 (red). NUT on 15q13 was probed using telomeric BAC clones 1H8 and 64o3B (green) and centromeric clones 1084a12 and 3d4 (red). Split apart of NUT and BRD4 was deemed consistent with BRD4-NUT fusion. Dual-color bring-together FISH assays were carried out for detection of BRD3-NUT fusion on FFPE tissue sections. BRD3 on 9q34.2 was probed using telomeric tandem BAC clones RP11-145e17 and RP11-92b21 (red) and NUT was probed using telomeric BAC clones as above. Slides with greater than 80% hybridization efficiency in four areas (200 cells/area) of the tissue section were considered interpretable. The clinical, radiographic, and pathologic features of the eight patients identified with NMC in the institutional consultative practice are detailed in TABLE 1, TABLE 2, TABLE 3. Selected radiographic, pathologic, and/or molecular features of cases 3, 5, 6, 7, and 8 have been included in previous reports.1French CA Rahman S Walsh EM et al.NSD3-NUT fusion oncoprotein in NUT midline carcinoma: Implications for a novel oncogenic mechanism.Cancer Discov. 2014; 4: 928-941Crossref PubMed Scopus (148) Google Scholar,13Filippakopoulos P Qi J Picaud S et al.Selective inhibition of BET bromodomains.Nature. 2010; 468: 1067-1073Crossref PubMed Scopus (2847) Google Scholar,15Bair RJ Chick JFB Chauhan NR et al.Demystifying NUT midline carcinoma: Radiologic and pathologic correlations of an aggressive malignancy.AJR Am J Roentgenol. 2014; 203: W391-W399Crossref PubMed Scopus (27) Google Scholar,16Grayson AR Walsh EM Cameron MJ et al.MYC, a downstream target of BRD-NUT, is necessary and sufficient for the blockade of differentiation in NUT midline carcinoma.Oncogene. 2014; 33: 1736-1742Crossref PubMed Scopus (117) Google Scholar The mean age of the patients at the time of diagnosis was 41 years (median 30, range 21–68). Clinical history was available for seven patients. Of these, six presented with a history of cough for one to three months preceding their diagnosis and three complained of shoulder and/or flank pain. One patient had a long standing history of pipe smoking; all others were never or light smokers (Table 1). All were otherwise previously healthy.TABLE 1Clinical Features of Patients Diagnosed with Primary Pulmonary NUT Midline CarcinomaCase #AgeSexTobacco HistoryPresenting SymptomsTreatmentOutcomeSurvival Time (Months)References168FUnknownUnknownUnknownDeath1None221FNeverRight flank and shoulder pain, cough × 1 moChemotherapyDeath4None323M2-pack yearsCough × 2 mosChemotherapy Extrapleural pneumonectomyDeath2Bair et al. (2014)463FNeverCough × 6 mos, right chest/back/shoulder painChemotherapyDeath2None537MNeverCough × 3 mosChemotherapyDeath1French et al. (2014)663MPipe smoker, 40 yrsDyspnea, cough, hemoptysis × 2 mos−Death1Bair et al. (2014)726MNeverFever, URI × 2 mosChemotherapyDeath2Bair et al. (2014)830M3-pack yearsShoulder pain, cough with hemoptysis × 1 moChemotherapyDeath5Bair et al. (2014) Filippakopoulos et al. (2010), Grayson et al. (2014)929F20-pack yearsCough, fever × 2 mosChemotherapy, radiationDeath3None Open table in a new tab TABLE 2Radiographic Features of Primary Pulmonary NUT Midline CarcinomaCase #SiteSize (cm)LungPleuraContralateral Lung InvolvementLymphadenopathyExtrathoracic SitesPET1No images2RLL, central5 × 5Postobstructive atelectasisLarge effusion Pleural noduleNoneMediastinal Subcarinal Hilar(R) + necrosisSubcutis, boneIntensely FDG avid, including bone and soft tissue metastases3RLL, central11 × 6Postobstructive atelectasisLarge effusion, pleural nodules with central necrosisSmall left-sided effusionMediastinal Subcarinal Hilar(R) + necrosisNone detectedIntensely FDG avid with central photopenia4RUL, central8 × 5Postobstructive atelectasis, lymphangitic spreadSmall effusionNoneSupraclavicular Hilar Mediastinal Axillary (B)(R) retrocrural and aortocaval nodes, boneIntensely FDG avid5RLL, central7 × 4Postobstructive atelectasisLarge effusion Pleural thickeningTrace left effusionSupraclavicular Hilar Mediastinal(B) Paraesophageal(L)Liver, boneN/A6LUL, central11 × 10Postobstructive atelectasis, lymphangitic spreadLarge effusion Pleural nodulesSmall right effusionSupraclavicular Mediastinal(B) Hilar(L)None detectedN/A7RLL, central9 × 8Postobstructive atelectasisSmall right effusionTrace left effusionMediastinal Subcarinal Hilar(R)None detectedIntensely FDG avid with central photopenia8LLL, central8 × 6Postobstructive atelectasisModerate effusion Pleural nodulesnoneMediastinal(B) Subcarinal Hilar(L) + necrosisLiver, boneN/A9RML10 × 10Postobstructive atelectasisSmall right effusionNoneHilar (B) Mediastinal (B)NoneIntensely FDG avidRLL, right lower lobe; RML, right middle lobe; RUL, right upper lobe; LUL, left upper lobe; LLL, left lower lobe; N/A, not available; B, bilateral; PET, positron emission tomography; FDG, 18F fluorodeoxyglucose. Open table in a new tab TABLE 3Pathologic Features of Primary Pulmonary NUT Midline CarcinomaCase #Suggested DiagnosisP63 ExpressionTTF-1 ExpressionKeratin ExpressionNeuroendocrine Marker ExpressionNUT IHC ResultFISH Result1LymphomaDiffuseNegativeMNF-116 (focal)Negative for synaptophysin, chromogranin, and CD56PositiveBRD4-NUT fusion2NUT midline carcinomaScattered cellsNDPan-K, Cam5.2NDPositiveBRD4-NUT fusion3Thymic carcinomaMultifocalNegativeAE1/AE3(focal)NDPositiveBRD4-NUT fusion4Poorly differentiated NSCLCFocalap40 was also examined in this case and was positive.FocalAE1/AE3, CK5/6, CK7 (focal), CK20 (focal)Negative for synaptophysin, chromograninPositiveVariant NUT rearrangement5Germ cell tumorMultifocal to diffuseFocalCam5.2, AE1/AE3(focal)Positive CD56 (focal), negative for synaptophysin, chromograninPositiveBRD4-NUT fusion6NUT midline carcinomaDiffuseNegativeCK7 (focal), CK20 (focal), CK5/6(focal)Negative for synaptophysin, chromogranin, and CD56PositiveBRD3-NUT fusion7Adenosquamous carcinomaDiffuseNegativeCam 5.2, AE1/AE3(focal), CK5/6 (focal)Negative for synaptophysinPositiveBRD4-NUT fusion8Poorly differentiated carcinomaDiffuseNegativeCam5.2, AE1/AE3Positive for synaptophysin (focal), negative for chromograninPositiveBRD4-NUT fusion9NSCLCScatteredFocalNDNDPositiveBRD4-NUT fusionND, not done; NSCLC, non–small-cell lung carcinoma; Pan-K, Pan-cytokeratin; CK7, cytokeratin 7; CK20, cytokeratin 20; CK5/6, cytokeratin 5/6; TTF-1, thyroid transcription factor-1; FISH, fluorescence in situ hybridization; IHC, immunohistochemistry.a p40 was also examined in this case and was positive. Open table in a new tab RLL, right lower lobe; RML, right middle lobe; RUL, right upper lobe; LUL, left upper lobe; LLL, left lower lobe; N/A, not available; B, bilateral; PET, positron emission tomography; FDG, 18F fluorodeoxyglucose. ND, not done; NSCLC, non–small-cell lung carcinoma; Pan-K, Pan-cytokeratin; CK7, cytokeratin 7; CK20, cytokeratin 20; CK5/6, cytokeratin 5/6; TTF-1, thyroid transcription factor-1; FISH, fluorescence in situ hybridization; IHC, immunohistochemistry. Chest CT imaging was available for review in seven patients (Table 2). In all cases, the primary lung mass was centrally located, with a predilection for the lower lobes (five of seven) and the right side (five of seven). The primary tumor consistently presented as a large mass (range 5–11 cm in longest diameter) with irregular borders and low density components suggestive of necrosis and was confluent with ipsilateral hilar and mediastinal lymph nodes (Fig. 1). Ipsilateral pleural disease was consistently present with pleural effusion in all cases, with accompanying pleural masses or thickening noted in five cases. The contralateral lung had no evidence of disease involvement on CT in all cases, other than trace or small pleural effusions in four cases. Regional adenopathy was similarly more pronounced on the side of the dominant mass and was noted in all cases; bilateral mediastinal lymphadenopathy was present in four cases, including three cases with bilateral supraclavicular nodal involvement. In four cases evaluated with PET/CT, all sites of tumor were intensely FDG-avid with SUVmax measuring as high as 10 in some cases. In two of the cases with PET, central photopenia was noted in the lung mass suggesting necrosis. Definite bone involvement was seen in three patients, present as multiple lytic lesions on CT that were FDG-avid on PET/CT. In one case with multiple bone metastasis on PET and CT, bone scintigraphy was negative. Other distant sites of metastasis detected by CT and/or PET imaging included liver, subcutaneous soft tissue, and retroperitoneal lymph nodes. All cases were negative for brain metastases on imaging (five cases with brain MRI and two cases with head CT). Pathologic features are detailed in Table 3. Six of eight cases arrived in consultation with another suggested diagnosis, including NSCLC, not otherwise specified, adenosquamous carcinoma, thymic carcinoma, germ cell tumor, and lymphoma. Characteristic morphologic features included nested to sheetlike growth of a monomorphic proliferation of intermediate-sized round to epithelioid tumor cells with high nuclear:cytoplasmic ratio, open chromatin, variably prominent nucleoli, and small amounts of pale, amphophilic cytoplasm. Two cases showed multifocal crush artifact and nuclear molding, features most commonly associated with small cell carcinomas. One case, obtained from an extrapleural pneumonectomy specimen performed after chemotherapy, showed polygonal cells with prominent cherry-red nucleoli and more abundant pale, eosinophilic cytoplasm, raising a differential diagnosis of malignant melanoma (Supplementary Figure 1, SDC, http://links.lww.com/JTO/A826). One case originally classified as an adenosquamous carcinoma showed a population of primitive appearing cells with the cytomorphology described above admixed with a florid proliferation of columnar respiratory epithelial cells and a brisk polymorphonuclear infiltrate (Supplementary Figure 2A, SDC, http://links.lww.com/JTO/A826). Immunohistochemistry showed that the primitive-appearing cells were diffusely p63 and NUT positive and the associated columnar cell proliferation (favored to represent a reactive population) was TTF-1 positive but p63 and NUT negative (Supplementary Figure 2B, SDC, http://links.lww.com/JTO/A826, showing p63 staining in tumor cells; 2C, showing TTF-1 staining in reactive columnar cell proliferation; and 2D, showing nuclear pattern of Nut protein expression in tumor cells; all panels at 400×). All cases in the series showed at least scattered p63 expression, and all cases showed at least focal cytokeratin expression. One tumor (case 8) showed discreet islands of keratinization by CK5/6 IHC. Interestingly, two cases, including one obtained from a supraclavicular lymph node biopsy (case 5; Fig. 2A) showed focal (<10%), weak nuclear TTF-1 expression (Fig. 2B). Neuroendocrine marker staining was performed in six cases and was focally positive in two (Table 3), including in one case with morphologic features of small cell carcinoma (Fig. 2C, D). MIB-1 proliferation index was 80–100% in two cases stained. A total of 166 cases of in-house biopsies were successfully screened for NUT overexpression by immunohistochemistry. The original diagnoses are listed in Table 4. Based on recommendations that the diagnosis of NMC be considered only for nongland forming epithelioid malignancies,8Bauer DE Mitchell CM Strait KM et al.Clinicopathologic features and long-term outcomes of NUT midline carcinoma.Clin Cancer Res. 2012; 18: 5773-5779Crossref PubMed Scopus (254) Google Scholar tumors diagnosed morphologically as adenocarcinoma were excluded from this study. Of this cohort, 54 were originally diagnosed as NSCLC. Additional immunohistochemistry using TTF-1 and p40 was performed to further subclassify these cases according to IASLC criteria,17Travis WD Brambilla E Noguchi M et al.Diagnosis of lung cancer in small biopsies and cytology: Implications of the 2011 International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification.Arch Pathol Lab Med. 2013; 137: 668-684Crossref PubMed Scopus (293) Google Scholar with 31 reclassified as NSCLC, favor adenocarcinoma, eight reclassified as NSCLC, favor squamous cell carcinoma, and 15 remaining as NSCLC, not otherwise specified.TABLE 4Diagnoses of Lung Cancer Cases Screened by NUT ImmunohistochemistryDiagnosisNumberSQC Morphologic SQC66 NSCLC, favor SQC8ADC ADC, poorly differentiated3 NSCLC, favor ADC31 Adenosquamous carcinoma4Undifferentiated carcinoma NSCLC, not otherwise specified15 Poorly differentiated carcinoma4 Large cell carcinoma2Neuroendocrine carcinoma SCLC25 LCNEC4 Combined SCLC/LCNEC2 Combined SCLC/NSCLC2Total166SQC, squamous cell carcinoma; NSCLC, non–small-cell lung cancer; ADC, adenocarcinoma; SCLC, small-cell lung carcinoma; LCNEC, large cell neuroendocrine carcinoma. Open table in a new tab SQC, squamous cell carcinoma; NSCLC, non–small-cell lung cancer; ADC, adenocarcinoma; SCLC, small-cell lung carcinoma; LCNEC, large cell neuroendocrine carcinoma. NUT overexpression was identified in one case (one of 166 or 0.6%), in an endobronchial biopsy originally diagnosed as NSCLC, and reclassified as NSCLC, NOS based on scattered p63 positivity and focal (<10%) TTF-1 expression in the same cell population. Although this was a limited biopsy, it had features resembling those seen in the case illustrated in Supplementary Figure 2 (SDC, http://links.lww.com/JTO/A826), with primitive-appearing round to epithelioid cells adjacent to a population of proliferative columnar epithelium and a brisk polymorphonuclear infiltrate (Fig. 3A). NUT protein expression was confined to the primitive-appearing cells (Fig. 3B). A BRD4-NUT translocation was confirmed by FISH (Fig. 3C, D). This case was therefore reclassified as NMC. Notably, the patient from whom this biopsy was derived was a 29-year-old woman with a 20-pack year history of smoking and a 2-month history of cough and fevers. CT and PET/CT imaging showed a large, FDG-avid mass (10 cm in diameter) located in the right middle lobe with postobstructive atelectasis and small right pleural effusion, and bilateral hilar and mediastinal lymphadenopathy. No evidence of involvement was noted in the left lung, and no distant metastasis was noted on PET or on brain MRI. She was treated as stage IIIB squamous cell carcinoma (based on p63 positivity in a subsequent pleural biopsy) with carboplatin and taxol and radiation therapy; however, she died of disease 3 months after her diagnosis. Descriptions of primary pulmonary NMC have been limited to a few individual case reports or small case series;9Tanaka M Kato K Gomi K et al.NUT midline carcinoma: Report of 2 cases suggestive of pulmonary origin.Am J Surg Pathol. 2012; 36: 381-388Crossref PubMed Scopus (50) Google Scholar, 10Haruki N Kawaguchi KS Eichenberger S et al.Cloned fusion product from a rare t(15;19)(q13.2;p13.1) inhibit S phase in vitro.J Med Genet. 2005; 42: 558-564Crossref PubMed Scopus (36) Google Scholar, 11Parikh SA French CA Costello BA et al.NUT midline carcinoma: An aggressive intrathoracic neoplasm.J Thorac Oncol. 2013; 8: 1335-1338Abstract Full Text Full Text PDF PubMed Scopus (32) Google Scholar,18Dang TP Gazdar AF Virmani AK et al.Chromosome 19 translocation, overexpression of Notch3, and human lung cancer.J Natl Cancer Inst. 2000; 92: 1355-1357Crossref PubMed Scopus (217) Google Scholar as a result a clear clinicopathologic description of this entity is lacking. Our series is the largest reported to date and offers complete clinical, radiographic, and pathologic detail for eight of the nine included patients. The median age of diagnosis for lung cancers overall is 70 years, as compared with median of 30 years (mean of 41) in this cohort of NMC patients.19Howlader N Noone AM Krapcho M et al.SEER Cancer Statistics Review, 1975–2011. National Cancer Institute, Bethesda, MD2014Available from: http://seer.cancer.gov/csr/1975_2011/Google Scholar Overall, two patients had significant smoking history, but six had no or negligible tobacco exposure. At presentation, all patients complained of a month or more of cough and some had concurrent chest or shoulder pain. Despite the original descriptions of this entity in pediatric patients,20Kubonishi I Takehara N Iwata J et al.Novel t(15;19)(q15;p13) chromosome abnormality in a thymic carcinoma.Cancer Res. 1991; 51: 3327-3328PubMed Google Scholar it is evident that older adults are not spared. Therefore, although NMC should always be included in the differential diagnosis of a malignant lung tumor presenting in a young person, it should also be considered in older adults, even those with a substantial smoking history, when the clinical course appears unusually aggressive. Despite chemo- or chemoradiotherapy, all patients were dead of disease within 5 months. Interestingly, the survival time reported for NMC in the largest published series, including tumors arising at all sites, was 6.7 months,8Bauer DE Mitchell CM Strait KM et al.Clinicopathologic features and long-term outcomes of NUT midline carcinoma.Clin Cancer Res. 2012; 18: 5773-5779Crossref PubMed Scopus (254) Google Scholar whereas in our series of primary pulmonary NMC, the median survival time was 2.2 months (66 days). Although it is possible that primary pulmonary NMC are intrinsically more aggressive than NMC arising at other sites, the shorter survival time may simply reflect a relatively delayed onset of clinical symptoms for primary lung tumors as compared, for instance, with primary head and neck tumors, another common site of NMC presentation. CT imaging of primary pulmonary NMC, although not necessarily specific, appears to have some characteristic features that are consistent across the cases in this study. All cases presented with a large primary lung mass (≥5 cm in diameter) that was confluent with hilar and mediastinal adenopathy, often associated with postobstructive atelectasis and ipsilateral pleural involvement. Notably, the contralateral lung was essentially spared in all cases. Bones were the most common site of extrathoracic involvement, with three of eight cases with available imaging showing definite bony metastases in the form of purely lytic lesions on CT scan, which were more easily detected on PET due to marked FDG avidity. In one case with multiple bone metastasis on PET and CT, bone scintigraphy was negative. This observation is consistent with other published reports and suggests that a negative bone scan may not reliably exclude metastases in this entity.15Bair RJ Chick JFB Chauhan NR et al.Demystifying NUT midline carcinoma: Radiologic and pathologic correlations of an aggressive malignancy.AJR Am J Roentgenol. 2014; 203: W391-W399Crossref PubMed Scopus (27) Google Scholar,21Rosenbaum DG Teruya-Feldstein J Price AP et al.Radiologic features of NUT midline carcinoma in an adolescent.Pediatr Radiol. 2012; 42: 249-252Crossref PubMed Scopus (19) Google Scholar Eight patients had staging head imaging and all were negative for brain metastases. This is a notable observation, given that primary lung carcinomas have the highest incidence of brain metastases compared with other primary sites, with an incidence of nearly 30% in stage IV disease.22Barnholtz-Sloan JS Sloan AE Davis FG et al.Incidence proportions of brain metastases in patients diagnosed (1973 to 2001) in the Metropolitan Detroit Cancer Surveillance System.J Clin Oncol. 2004; 22: 2865-2872Crossref PubMed Scopus (1140) Google Scholar,23Schouten LJ Rutten J Huveneers HA et al.Incidence of brain metastases in a cohort of patients with carcinoma of the breast, colon, kidney, and lung and melanoma.Cancer. 2002; 94: 2698-2705Crossref PubMed Scopus (757) Google Scholar However, given that brain metastases have been observed in NMC,24Polsani A Braithwaite KA Alazraki AL et al.NUT midline carcinoma: An imaging case series and review of literature.Pediatr Radiol. 2012; 42: 205-210Crossref PubMed Scopus (29) Google Scholar the findings may be due to the fact that these patients did not live long enough to develop brain metastases. The cytomorphology of NMC has been described extensively in the literature, and the appearance of the tumor cells in primary pulmonary NMC recapitulates that reported at other sites.6Stelow EB Bellizzi AM Taneja K et al.NUT rearrangement in undifferentiated carcinomas of the upper aerodigestive tract.Am J Surg Pathol. 2008; 32: 828-834Crossref PubMed Scopus (168) Google Scholar,7Evans AG French CA Cameron MJ et al.Pathologic characteristics of NUT midline carcinoma arising in the mediastinum.Am J Surg Pathol. 2012; 36: 1222-1227Crossref PubMed Scopus (84) Google Scholar,25Bellizzi AM Bruzzi C French CA et al.The cytologic features of NUT midline carcinoma.Cancer. 2009; 117: 508-515PubMed Google Scholar The histologic appearance may be readily confused with other high grade malignancies; in our series, other proposed diagnoses included lymphoma, germ cell tumor, and adenosquamous carcinoma, in addition to relatively nonspecific diagnoses, such as poorly differentiated carcinoma or NSCLC. Additional considerations may be small cell carcinoma, in tumors with extensive crush artifact, or melanoma, in tumors with pronounced nucleoli, as we observed in a surgically resected NMC after neoadjuvant chemotherapy. Notably, two cases in this series showed focal CD56 and/or synaptophysin expression, findings that may further lead to a misdiagnosis of small cell carcinoma. In a recent series, two of eight patients diagnosed with small-cell lung carcinoma under the age of 40 were retrospectively re-diagnosed with NMC based on positive NUT expression and rearrangement by FISH.26Taniyama TK Nokihara H Tsuta K et al.Clinicopathological features in young patients treated for small-cell lung cancer: Significance of immunohistological and molecular analyses.Clin Lung Cancer. 2014; 15: 244-247Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar One tumor also showed subset positivity of CD56, highlighting the nonspecific character of neuroendocrine marker expression and the need to maintain a broad differential when diagnosing high grade carcinomas in young patients. In contrast to reports of NMC arising in the anterior mediastinum,7Evans AG French CA Cameron MJ et al.Pathologic characteristics of NUT midline carcinoma arising in the mediastinum.Am J Surg Pathol. 2012; 36: 1222-1227Crossref PubMed Scopus (84) Google Scholar primary pulmonary NMC showed consistent keratin expression. Application of histone deacetylase inhibitors to NMC cells in vitro and in vivo drives them toward squamous differentiation.5Schwartz BE Hofer MD Lemieux ME et al.Differentiation of NUT midline carcinoma by epigenomic reprogramming.Cancer Res. 2011; 71: 2686-2696Crossref PubMed Scopus (150) Google Scholar In keeping with the hypothesis that NMC represents a subtype of squamous cell carcinoma all cases in our series showed at least scattered positivity for p63. From a diagnostic standpoint, it is important to note that three of the nine cases also had focal TTF-1 expression. TTF-1 with focal or multifocal p63 coexpression is not uncommon in lung tumors and favors the diagnosis of adenocarcinoma.27Rekhtman N Ang DC Sima CS et al.Immunohistochemical algorithm for differentiation of lung adenocarcinoma and squamous cell carcinoma based on large series of whole-tissue sections with validation in small specimens.Mod Pathol. 2011; 24: 1348-1359Crossref PubMed Scopus (268) Google Scholar However, extensive p63/p40 expression with focal TTF-1 in the same tumor cell population is highly unusual among lung carcinomas and should bring NMC into consideration. The significance of TTF-1 expression in this tumor type is unclear; it may hint at the origin of primary pulmonary NMC from a pluripotent respiratory epithelial cell. Alternatively, it may simply represent aberrant TTF-1 expression similar to that reported in extrapulmonary small cell carcinomas.28Agoff SN Lamps LW Philip AT et al.Thyroid transcription factor-1 is expressed in extrapulmonary small cell carcinomas but not in other extrapulmonary neuroendocrine tumors.Mod Pathol. 2000; 13: 238-242Crossref PubMed Scopus (292) Google Scholar Given its rarity and likely underdiagnosis, the prevalence of NMC among patients with lung cancer is unknown. Based on the data from Haruki et al.10Haruki N Kawaguchi KS Eichenberger S et al.Cloned fusion product from a rare t(15;19)(q13.2;p13.1) inhibit S phase in vitro.J Med Genet. 2005; 42: 558-564Crossref PubMed Scopus (36) Google Scholar, one may conclude that this number is likely less than 1%. Using a highly specific IHC-based screen of a cohort of consecutive diagnostic biopsies obtained at BWH, we retrospectively identified one primary pulmonary NMC among 166 tested cases of lung carcinoma lacking morphologic features of adenocarcinoma. This one case, from 2008, was diagnosed first as a NSCLC and on a subsequent biopsy as squamous cell carcinoma, based on p63 expression. Therefore, in this institutional series, primary pulmonary NMC similarly occurs in less than 1% of tumors that may be considered in the morphologic differential diagnosis. In conclusion, we demonstrate that primary pulmonary NMC, although rare, has characteristic diagnostic features. In this case series, the stereotypical patient was otherwise healthy, typically with minimal smoking history, had a large burden of unilateral disease involving lung, pleura, and mediastinal lymph nodes, and a primitive tumor cell population showing keratin and p63 or p40 expression on biopsy. Tumors with these clinicopathologic and radiographic features should undergo screening with either NUT IHC and/or FISH. NMC of the lung is uniformly and rapidly lethal and thus prompt recognition is necessary to permit proper patient counseling and hopefully to eventually offer effective targeted therapy. Download .pptx (4.05 MB) Help with pptx files
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