Malignant PEComa involving the mandible: report of a unique case
2012; Elsevier BV; Volume: 117; Issue: 1 Linguagem: Inglês
10.1016/j.oooo.2012.03.018
ISSN2212-4411
AutoresJason Untrauer, Peter J. Giannini, Geoffrey A. Talmon, Sonny L. Johansson,
Tópico(s)Histiocytic Disorders and Treatments
ResumoWe report a unique case of a malignant perivascular epithelioid cell neoplasm (PEComa) presenting as a slow-growing mandibular lesion in a 77-year-old Caucasian female. Primary osseous involvement by PEComas is rare. This is the first reported case of a malignant PEComa arising within the jaw. The patient is currently free of disease 2 years after treatment. We report a unique case of a malignant perivascular epithelioid cell neoplasm (PEComa) presenting as a slow-growing mandibular lesion in a 77-year-old Caucasian female. Primary osseous involvement by PEComas is rare. This is the first reported case of a malignant PEComa arising within the jaw. The patient is currently free of disease 2 years after treatment. Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal tumors sharing a characteristic cell type, the so-called perivascular epithelioid cell (PEC). They include angiomyolipomas, pulmonary clear cell “sugar” tumors, lymphangioleiomyomatosis, clear cell myomelanocytic tumor of the falciform ligament, and extrapulmonary clear cell sugar tumors.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google Scholar The PEC was first described by Bonetti et al. in 1991 as being characterized by an epithelioid shape, clear or eosinophilic cytoplasm, and a perivascular location.2Bonetti F. Pea M. Martignoni G. Zamboni G. Iuzzolino P. Cellular heterogeneity in lymphangiomyomatosis of the lung.Hum Pathol. 1991; 22: 727-728Abstract Full Text PDF PubMed Scopus (70) Google Scholar These tumors typically exhibit immunoreactivity for smooth muscle markers including actin or desmin, as well as melanocytic markers such as HMB45 and Melan-A. A normal cellular counterpart to the PEC has yet to be identified.Although PEComas preferentially occur at visceral, retroperitoneal, and abdominopelvic locations, they have been increasingly reported in other locations, including the head and neck. Primary bone involvement is exceedingly rare. To date, no primary osseous PEComas involving the jaws have been reported. This case represents the first report of a malignant PEComa involving the mandible.Report of a CaseA 77-year-old Caucasian female presented to the Department of Oral and Maxillofacial Surgery, University of Nebraska Medical Center (Omaha, Nebraska), with a >6-month history of a slow-growing mass involving the left posterior mandible (Figure 1). She denied any pain or paresthesia along the distribution of V3 or any recent unintentional weight loss. Past medical history was significant for coronary artery disease, type 2 diabetes mellitus, hypothyroidism, hypertension, and hyperlipidemia. Past surgical history was significant for a triple coronary artery bypass 4 years prior. The social history was unremarkable. On clinical exam the patient was found to have a 4 × 5 cm sessile submucosal mass involving the left posterior edentulous mandible exhibiting buccal and lingual extension (Figure 2). The mass was nontender to palpation. Left V3 sensation was intact. Her neck was free of lymphadenopathy. The patient's lungs were clear to auscultation and her abdomen was soft and without masses on palpation. A pantomograph demonstrated bony involvement of the left ramus. A head and neck computerized tomographic examination revealed a 5 × 5 cm lesion involving the left mandibular ramus and body with perforation of the medial and lateral cortices of the ramus (Fig. 3, Fig. 4, Fig. 5, Fig. 6). An incisional biopsy was performed, which proved difficult to diagnose histopathologically. In consultation with the pathologist it was believed that the sample consisted primarily of benign-appearing epithelioid and spindle-shaped cells with a neural or ganglioid appearance. The immunohistochemical staining profile did not support a diagnosis of a neural or ganglioid neoplasm; therefore, a preliminary diagnosis of atypical epithelioid lesion not otherwise specified was rendered with a recommendation for complete excision.Fig. 2Nodular tumor growth occurred during the interval between initial biopsy and resection at the initial biopsy site.View Large Image Figure ViewerDownload (PPT)Fig. 3Axial computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)Fig. 4Axial computed tomographic scan showing a large mass involving the left mandibular body and ramus.View Large Image Figure ViewerDownload (PPT)Fig. 5Coronal computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)Fig. 6Sagittal computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)The patient underwent a left hemimandibulectomy via a combined intraoral and extraoral approach (Fig. 7, Fig. 8). The frozen section at the distal bony margin was positive for tumor, necessitating reexcision. The mandible was reconstructed with a prebent reconstruction plate fashioned from a stereolithic model (Fig. 9, Fig. 10, Fig. 11). The patient had an uneventful postoperative course and was discharged on postoperative day 2. The specimen was sent to an outside institution for a second opinion. Ultimately, a diagnosis of malignant PEComa was made. The patient was then referred to the head and neck oncological service. A chest computerized tomographic scan was performed and was negative for lung metastasis. The patient was presented with a treatment plan involving wide resection and radiation. She elected to forgo further treatment in favor of monitoring for recurrence. The patient is currently free of tumor both clinically and radiographically 2 years after surgery.Fig. 7In situ view of the tumor.View Large Image Figure ViewerDownload (PPT)Fig. 8Resected specimen.View Large Image Figure ViewerDownload (PPT)Fig. 9Stereolithic model with prebent reconstruction plate.View Large Image Figure ViewerDownload (PPT)Fig. 10Fixated reconstruction plate.View Large Image Figure ViewerDownload (PPT)Fig. 11Postoperative pantomograph confirming adequate seating of condylar prosthesis within the glenoid fossa.View Large Image Figure ViewerDownload (PPT)Pathology findingsThe resected specimen measured 7.5 cm. Histopathologic analysis revealed a highly cellular, infiltrative neoplasm composed of spindle-to-oval cells exhibiting epithelioid features set within a collagenous stroma (Fig. 12, Fig. 13, Fig. 14, Fig. 15). Pseudoinclusions and focally prominent nucleoli were also observed. A focal mitotic index of 10/50 high-power fields was observed. Immunohistochemical staining was positive for vimentin, Melan-A (Fig. 16, Fig. 17), neuron-specific enolase, and CD56. The neoplasm was negative for the following immunohistochemical markers: smooth muscle actin, desmin, HMB45, S100, epithelial membrane antigen, chromogranin, synaptophysin, CD31, CD57, pankeratin, inhibin, and glial fibrillary acidic protein. Cytogenetic studies were negative for chromosomal abnormalities.Fig. 12Hematoxylin and eosin photomicrograph of the lesion demonstrating pleomorphic epithelioid cells with an eosinophilic to clear cytoplasm (10×).View Large Image Figure ViewerDownload (PPT)Fig. 13High-power hematoxylin and eosin photomicrograph reveals pleomorphic epithelioid cells set within a collagenous stroma (20×).View Large Image Figure ViewerDownload (PPT)Fig. 14High-power hematoxylin and eosin photomicrograph reveals a more cellular region of pleomorphic epithelioid cells with pale eosinophilic cytoplasm. Some of the cells are multinucleated (20×).View Large Image Figure ViewerDownload (PPT)Fig. 15Hematoxylin and eosin photomicrograph reveals multinucleated and pleomorphic neoplastic cells with prominent nucleoli (40×).View Large Image Figure ViewerDownload (PPT)Fig. 16Immunohistochemical staining for Melan-A showed positivity of the neoplastic cells (5×).View Large Image Figure ViewerDownload (PPT)Fig. 17High-power photomicrograph reveals cytoplasmic staining of the neoplastic cells for Melan-A (20×).View Large Image Figure ViewerDownload (PPT)DiscussionPEComas are a rare group of mesenchymal tumors sharing morphologic, immunohistochemical, ultrastructural, and genetically distinctive features.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google Scholar The PEC was first described by Bonetti. His description of the PEC followed reports of HMB-45 immunoreactivity and the presence of premelanosomes in both clear cell sugar tumors (CCST) of the lung and the epithelioid clear cell component of angiomyolipoma (AML) of the kidney and liver.3Koenig A. Quaas A. Ries T. Yekebas E. Gawad K. Vashist Y. et al.Perivascular epithelioid cell tumour (PEComa) of the retroperitoneum—a rare tumor with uncertain malignant behavior: a case report.J Med Case Rep. 2009; 3: 62Crossref PubMed Scopus (12) Google Scholar, 4Pea M. Bonetti F. Zamboni G. Martignoni G. Fiore-Donati L. Doglioni C. Clear cell tumor and angiomyolipoma.Am J Surg Pathol. 1991; 15: 199-202Crossref PubMed Scopus (119) Google Scholar, 5Pea M. Bonetti F. Zamboni G. Martignoni G. Riva M. Colombari R. et al.Melanocyte-marker-HMB-45 is regularly expressed in angiomyolipoma of the kidney.Pathology. 1991; 23: 185-188Crossref PubMed Scopus (226) Google Scholar, 6Weeks D.A. Malott R.L. Arnesen M. Arnesen M. Zuppan C. Aitken D. Mierau G. Hepatic angiomyolipoma with striated granules and positivity with melanoma-specific antibody (HMB-45): a report of two cases.Ultrastruct Pathol. 1991; 15: 563-571Crossref PubMed Scopus (120) Google Scholar, 7Gaffey M.J. Mills S.E. Zarbo R.J. Weiss L.M. Gown A.M. Clear cell tumor of the lung Immunohistochemical and ultrastructural evidence of melanogenesis.Am J Surg Pathol. 1991; 15: 644-653Crossref PubMed Scopus (144) Google Scholar, 8Gal A.A. Koss M.N. Hochholzer L. Chejfec G. An immunohistochemical study of benign clear cell (“sugar”) tumor of the lung.Arch Pathol Lab Med. 1991; 115: 1034-1038PubMed Google Scholar, 9Hornick J.L. Fletcher C.D.M. PEComa: what do we know so far?.Histopathology. 2006; 48: 75-82Crossref PubMed Scopus (390) Google Scholar Bonetti et al. proposed the concept of PECs as a cellular link among AML, CCST, and lymphangiomyomatosis (LAM), after confirmation of HMB45 positivity of the muscle-like spindle cells of LAM.2Bonetti F. Pea M. Martignoni G. Zamboni G. Iuzzolino P. Cellular heterogeneity in lymphangiomyomatosis of the lung.Hum Pathol. 1991; 22: 727-728Abstract Full Text PDF PubMed Scopus (70) Google Scholar, 9Hornick J.L. Fletcher C.D.M. PEComa: what do we know so far?.Histopathology. 2006; 48: 75-82Crossref PubMed Scopus (390) Google Scholar, 10Bonetti F. Chiodera P.L. Pea M. Martignoni G. Bosi F. Zamboni G. Mariuzzi G.M. Transbronchial biopsy in lymphangiomyomatosis of the lung HMB45 for diagnosis.Am J Surg Pathol. 1993; 17: 1092-1102Crossref PubMed Scopus (179) Google Scholar, 11Chan J.K. Tsang W.Y. Pau M.Y. Tang M.C. Pang S.W. Fletcher C.D. Lymphangiomyomatosis and angiomyolipoma: closely related entities characterized by hamartomatous proliferation of HMB-45-positive smooth muscle.Histopathology. 1993; 22: 445-455Crossref PubMed Scopus (203) Google Scholar The latter is an uncommon disease that usually affects premenopausal women and manifests as multiple nodular lung lesions consisting of a neoplastic-like proliferation of lymphatic channels and smooth muscle cells.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google ScholarThe unifying term PEComa was first introduced by Zamboni et al. in a 1996 case report, in which a CCST arising primarily in the pancreas was morphologically and immunophenotypically indistinguishable from its pulmonary counterpart.9Hornick J.L. Fletcher C.D.M. PEComa: what do we know so far?.Histopathology. 2006; 48: 75-82Crossref PubMed Scopus (390) Google Scholar, 12Zamboni G. Pea M. Martignoni G. Zancanaro C. Faccioli G. Gilioli E. et al.Clear cell “sugar” tumor of the pancreas A novel member of the family of lesions characterized by the presence of perivascular epithelioid cells.Am J Surg Pathol. 1996; 20: 722-730Crossref PubMed Scopus (309) Google Scholar The PEComa family includes AML, CCST, LAM, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, and unusual clear cell tumors of the pancreas, rectum, abdominal serosa, uterus, vulva, thigh, and heart.13Ruco L.P. Pilozzi E. Wedard B.M. Marzullo A. D'Andrea V. De ANtoni E. et al.Epithelioid lymphangioleiomyomatosis-like tumour of the uterus in a patient without tuberous sclerosis: a lesion mimicking epithelioid leiomyosarcoma.Histopathology. 1998; 33: 91-93Crossref Scopus (43) Google Scholar The gastrointestinal tract and uterus are the most common sites of involvement outside of the kidney.9Hornick J.L. Fletcher C.D.M. PEComa: what do we know so far?.Histopathology. 2006; 48: 75-82Crossref PubMed Scopus (390) Google ScholarSeveral of these conditions such as AML and LAM represent a subset of PEComas that are strongly associated with the tuberous sclerosis complex (TSC), a group of autosomal dominant genetic disorders caused by germline mutations of TSC1 and TSC2 tumor suppressor genes.14Kenerson H. Folpe A.L. Takayama T.K. Yeung R.S. Activation of the mTOR pathway in sporadic angiomyolipomas and other perivascular epithelioid cell neoplasms.Hum Pathol. 2007; 38: 1361-1371Abstract Full Text Full Text PDF PubMed Scopus (183) Google Scholar, 15Pan C.C. Chung M.Y. Ng K.F. Liu C.Y. Wang J.S. Chai C.Y. et al.Constant allelic alteration on chromosome 16p (TSC2 gene) in perivascular epithelioid cell tumour (PEComa): genetic evidence for the relationship of PEComa with angiomyolipoma.J Pathol. 2008; 214: 387-393Crossref PubMed Scopus (152) Google Scholar Under normal conditions, cytoplasmic TSC1 and TSC2 proteins inhibit mTOR, a protein kinase that regulates cell proliferation. In the absence of a normally functioning TSC1–TSC2 complex, mTOR activity increases, leading to the development of tumors in various organ systems, including the kidney, lung, brain, and skin. Disruptions of TSC genes have been identified in PEComas occurring within the TSC in addition to sporadic cases.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google ScholarIt has been suggested that PECs can modulate their morphology and immunophenotype depending on the microenvironment. In this context, PECs can either have pronounced muscle features with a spindle shape and greater positivity for actin than HMB45 or exhibit a more epithelioid morphology with strong positivity for HMB45 and weak to absent staining for actin.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google Scholar A normal cellular counterpart to the PEC has not been identified, but three current hypotheses exist: one hypothesis is that the tumor derives from undifferentiated cells of the neural crest with both smooth muscle and melanocytic phenotypes; a second hypothesis is that the PEC has a myoblastic, smooth muscle origin; and a third hypothesis postulates a pericyte origin.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google Scholar, 9Hornick J.L. Fletcher C.D.M. PEComa: what do we know so far?.Histopathology. 2006; 48: 75-82Crossref PubMed Scopus (390) Google ScholarAlthough the majority of PEComas are benign, subsets of this family behave much more aggressively, with potential for local recurrences, metastasis, and death.16Selvaggi F. Risio D. Claudi R. Cianci R. Angelucci D. Pulcini D. D'Aulerio A. Legnini M. et al.Malignant PEComa: a case report with emphasis on clinical and morphological criteria.BMC Surg. 2011; 11: 3Crossref Scopus (33) Google Scholar Relatively few malignant cases have been reported, with just over 50 cases of malignant PEComas having been reported in the literature. Recently, Folpe et al. suggested criteria for malignancy, including size >5 cm, mitotic count of more than 1 per 50 high-power fields, necrosis, infiltrative growth, hypercellularity, marked pleomorphism, and nuclear atypia.17Folpe A.L. Kwiatkowski D.J. Perivascular epithelioid cell neoplasms: pathology and pathogenesis.Hum Pathol. 2010; 41: 1-15Abstract Full Text Full Text PDF PubMed Scopus (258) Google Scholar Currently, surgical resection represents the best curative approach for primary PEComa at initial presentation as well as for local recurrences and metastasis because chemotherapy and radiotherapy have not demonstrated significant benefits.15Pan C.C. Chung M.Y. Ng K.F. Liu C.Y. Wang J.S. Chai C.Y. et al.Constant allelic alteration on chromosome 16p (TSC2 gene) in perivascular epithelioid cell tumour (PEComa): genetic evidence for the relationship of PEComa with angiomyolipoma.J Pathol. 2008; 214: 387-393Crossref PubMed Scopus (152) Google Scholar, 18Armah H.B. Parwani A.V. Perivascular epithelioid cell tumor.Arch Pathol Lab Med. 2009; 133: 648-654PubMed Google Scholar Rapamycin, a specific mTOR inhibitor, is currently being studied and is showing promise as a chemotherapeutic agent.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google ScholarAlthough PEComas can occur anywhere in the body, primary bony PEComas are extremely rare, with only four cases having previously been reported in the literature.19Insabato L. De Rosa G. Terracciano L.M. Fazioli F. Di Santo F. Rosai J. Primary monotypic epithelioid angiomyolipoma of bone.Histopathology. 2002; 40: 286-290Crossref Scopus (49) Google Scholar, 20Righi A. Dimosthenous K. Rosai J. PEComa: another member of the MiT tumor family?.Int J Surg Pathol. 2008; 16: 16-20Crossref Scopus (57) Google Scholar, 21Torii I. Kondo N. Takuwa T. Matsumoto S. Okumura Y. Sato A. et al.Perivascular epithelioid cell tumor of the rib.Virchows Arch. 2008; 452: 697-702Crossref Scopus (18) Google Scholar, 22Lian D.W. Chuah K.L. Cheng M.H. Yap W.M. Malignant perivascular epithelioid cell tumour of the fibula: a report and a short review of bone perivascular epithelioid cell tumour.J Clin Pathol. 2008; 61: 1127-1129Crossref Scopus (18) Google Scholar Two of these cases involved the fibula, one case involved the tibia, and one case involved the 6th rib. A case involving the skull has been reported; however, it is unclear whether this case evolved from the meninges.23Lehman N.L. Malignant PEComa of the skull base.Am J Surg Pathol. 2004; 28: 1230-1232Crossref Scopus (44) Google Scholar In these reported cases, patients ranged from 28 to 92 years of age. Two patients were female and two were male. None of the patients had TSC. Two of the cases were benign,19Insabato L. De Rosa G. Terracciano L.M. Fazioli F. Di Santo F. Rosai J. Primary monotypic epithelioid angiomyolipoma of bone.Histopathology. 2002; 40: 286-290Crossref Scopus (49) Google Scholar, 20Righi A. Dimosthenous K. Rosai J. PEComa: another member of the MiT tumor family?.Int J Surg Pathol. 2008; 16: 16-20Crossref Scopus (57) Google Scholar one case was considered to have malignant potential based on tumor invasion beyond the bony confines in association with overexpression of cyclin D1,21Torii I. Kondo N. Takuwa T. Matsumoto S. Okumura Y. Sato A. et al.Perivascular epithelioid cell tumor of the rib.Virchows Arch. 2008; 452: 697-702Crossref Scopus (18) Google Scholar and one case fulfilled the diagnostic criterion for malignancy.22Lian D.W. Chuah K.L. Cheng M.H. Yap W.M. Malignant perivascular epithelioid cell tumour of the fibula: a report and a short review of bone perivascular epithelioid cell tumour.J Clin Pathol. 2008; 61: 1127-1129Crossref Scopus (18) Google ScholarIn our case a diagnosis of malignant PEComa proved difficult both on initial biopsy and after complete resection secondary to the lack of a “clear-cut” staining profile. The difficulty of diagnosis after initial biopsy is a consistent theme in the literature and is attributed to the heterogeneity within the tumor specimen. Significantly, the resection specimen contained heterogenous cells that exhibited both spindle-shape and epithelioid morphologies. Notably, it did not stain for HMB45, actin, or desmin. It did, however, show positivity for Melan-A while exhibiting an overall staining profile that ruled out melanoma. A diagnosis of malignant PEComa was ultimately rendered based on the overall morphology, positivity for Melan-A, and an immunohistochemical profile inconsistent with melanoma. Melanoma was ruled out by lack of staining for S100, whereas undifferentiated clear cell sarcoma was ruled out by normal cytogenetic studies. A “malignant” designation was based on a tumor size of >5 cm, mitotic index >1/50 high-power fields, infiltrative growth pattern, high cellularity, and high nuclear grade with marked cellular pleomorphism.At the time of submission of this report, the patient has been recurrence free for 2 years despite having a positive bony margin on initial resection. Given the patient's age, health status, and uncertainty of the biological behavior of her disease, conservative monitoring for local recurrence for several years is likely to be the most prudent management option at this time. Perivascular epithelioid cell neoplasms (PEComas) are a family of mesenchymal tumors sharing a characteristic cell type, the so-called perivascular epithelioid cell (PEC). They include angiomyolipomas, pulmonary clear cell “sugar” tumors, lymphangioleiomyomatosis, clear cell myomelanocytic tumor of the falciform ligament, and extrapulmonary clear cell sugar tumors.1Martignoni G. Pea M. Reghellin D. Zamboni G. Bonetti F. PEComas: the past, the present and the future.Virchows Arch. 2008; 452: 119-132Crossref PubMed Scopus (380) Google Scholar The PEC was first described by Bonetti et al. in 1991 as being characterized by an epithelioid shape, clear or eosinophilic cytoplasm, and a perivascular location.2Bonetti F. Pea M. Martignoni G. Zamboni G. Iuzzolino P. Cellular heterogeneity in lymphangiomyomatosis of the lung.Hum Pathol. 1991; 22: 727-728Abstract Full Text PDF PubMed Scopus (70) Google Scholar These tumors typically exhibit immunoreactivity for smooth muscle markers including actin or desmin, as well as melanocytic markers such as HMB45 and Melan-A. A normal cellular counterpart to the PEC has yet to be identified. Although PEComas preferentially occur at visceral, retroperitoneal, and abdominopelvic locations, they have been increasingly reported in other locations, including the head and neck. Primary bone involvement is exceedingly rare. To date, no primary osseous PEComas involving the jaws have been reported. This case represents the first report of a malignant PEComa involving the mandible. Report of a CaseA 77-year-old Caucasian female presented to the Department of Oral and Maxillofacial Surgery, University of Nebraska Medical Center (Omaha, Nebraska), with a >6-month history of a slow-growing mass involving the left posterior mandible (Figure 1). She denied any pain or paresthesia along the distribution of V3 or any recent unintentional weight loss. Past medical history was significant for coronary artery disease, type 2 diabetes mellitus, hypothyroidism, hypertension, and hyperlipidemia. Past surgical history was significant for a triple coronary artery bypass 4 years prior. The social history was unremarkable. On clinical exam the patient was found to have a 4 × 5 cm sessile submucosal mass involving the left posterior edentulous mandible exhibiting buccal and lingual extension (Figure 2). The mass was nontender to palpation. Left V3 sensation was intact. Her neck was free of lymphadenopathy. The patient's lungs were clear to auscultation and her abdomen was soft and without masses on palpation. A pantomograph demonstrated bony involvement of the left ramus. A head and neck computerized tomographic examination revealed a 5 × 5 cm lesion involving the left mandibular ramus and body with perforation of the medial and lateral cortices of the ramus (Fig. 3, Fig. 4, Fig. 5, Fig. 6). An incisional biopsy was performed, which proved difficult to diagnose histopathologically. In consultation with the pathologist it was believed that the sample consisted primarily of benign-appearing epithelioid and spindle-shaped cells with a neural or ganglioid appearance. The immunohistochemical staining profile did not support a diagnosis of a neural or ganglioid neoplasm; therefore, a preliminary diagnosis of atypical epithelioid lesion not otherwise specified was rendered with a recommendation for complete excision.Fig. 3Axial computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)Fig. 4Axial computed tomographic scan showing a large mass involving the left mandibular body and ramus.View Large Image Figure ViewerDownload (PPT)Fig. 5Coronal computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)Fig. 6Sagittal computed tomographic scan exhibiting involvement of the left mandibular body and ramus, as well as violation of the buccal and lingual cortices.View Large Image Figure ViewerDownload (PPT)The patient underwent a left hemimandibulectomy via a combined intraoral and extraoral approach (Fig. 7, Fig. 8). The frozen section at the distal bony margin was positive for tumor, necessitating reexcision. The mandible was reconstructed with a prebent reconstruction plate fashioned from a stereolithic model (Fig. 9, Fig. 10, Fig. 11). The patient had an uneventful postoperative course and was discharged on postoperative day 2. The specimen was sent to an outside institution for a second opinion. Ultimately, a diagnosis of malignant PEComa was made. The patient was then referred to the head and neck oncological service. A chest computerized tomographic scan was performed and was negative for lung metastasis. The patient was presented with a treatment plan involving wide resection and radiation. She elected to forgo further treatment in favor of monitoring for recurrence. The patient is currently free of tumor both clinically and radiographically 2 years after surgery.Fig. 7In situ view of the tumor.View Large Image Figure ViewerDownload (PPT)Fig. 8Resected specimen.View Large Image Figure ViewerDownload (PPT)Fig. 9Stereolithic model with prebent reconstruction plate.View Large Image Figure ViewerDownload (PPT)Fig. 10Fixated reconstruction plate.View Large Image Figure ViewerDownload (PPT)Fig. 11Postoperative pantomograph confirming adequate seating of condylar prosthesis within the glenoid fossa.View Large Image Figure ViewerDownload (PPT)Pathology findingsThe resected specimen measured 7.5 cm. Histopathologic analysis revealed a highly cellular, infiltrative neoplasm composed of spindle-to-oval cells exhibiting epithelioid features set within a collagenous stroma (Fig. 12, Fig. 13, Fig. 14, Fig. 15). Pseudoinclusions and focally prominent nucleoli
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