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IgG4+ Rosai–Dorfman disease of the lung

2010; Wiley; Volume: 56; Issue: 5 Linguagem: Inglês

10.1111/j.1365-2559.2010.03519.x

1365-2559

Shaun Roberts, Richard Attanoos,

Eosinophilic Disorders and Syndromes

Sir: we note with interest a review article1 and editorial2 regarding IgG4-related systemic sclerosing disease. Other conditions have also been found with a significant IgG4+ plasma cell population, including Rosai–Dorfman disease (RD), suggesting a possible overlap between RD and IgG4-related disease.3 We describe a case of pulmonary RD with a prominent IgG4+ plasma cell population. The patient was a 61-year-old non-smoking man who, 2 months previously, had undergone a radical prostatectomy for Gleason grade 4+3 = 7 prostatic adenocarcinoma. Follow-up magnetic resonance imaging identified a suspicious spiculated nodule within the upper lobe of the left lung (Figure 1). The radiological differential diagnosis was between a pulmonary metastasis and a synchronous lung cancer. Spiculated mass within the upper lobe of the left lung. The patient was referred to the cardiothoracic surgeons, and an open biopsy produced a wedge of lung measuring 64 × 26 × 14 mm that contained a well-circumscribed, solid, white nodule measuring 21 mm in diameter. Microscopically, the nodule was fibrotic (Figure 2A) and composed of sheets of large histiocytoid cells with vesicular nuclei, prominent nucleoli and abundant eosinophilic cytoplasm (Figure 2B). Focal lymphocyte phagocytosis was seen in a minority of these histiocytoid cells (Figure 2C). In addition, the fibrotic nodule was composed of numerous plasma cells and lymphocytes. Immunohistochemistry showed these histiocytoid cells to be S100+ (Figure 2D). IgG4 immunohistochemistry was positive and, using the quantification method described by Shrestha et al.,3 had a significant score of 2 (Figure 2E). Three months following surgery, the patient remains asymptomatic and clinically well. Microscopic appearance of the lung lesion. The nodule is well circumscribed and fibrotic (A) and composed of sheets of large histiocytoid cells, plasma cells and lymphocytes (B) with focal emperipolesis (C, arrow). Immunohistochemistry shows the histiocytoid cells to be S100+ (D), and a significant proportion of the plasma cells are IgG4+ (E). RD is a benign proliferation of histiocytes of unknown aetiology.4 It is a rare condition typically affecting lymphoid tissue, hence its other more descriptive clinicopathological name of massive lymphadenopathy with sinus histiocytosis.5 Extranodal disease with or without nodal involvement was reported in 43% of the cases in the RD Registry, but only 2% had any lower respiratory tract involvement.4 In contrast to the demographics of our index case, pulmonary RD usually occurs in females within the teenage years. When symptomatic, patients present with shortness of breath and occasionally stridor.4 The radiological appearance is variable, hence tissue is required for a definitive diagnosis. Pulmonary RD has a significantly worse prognosis compared with the nodal form. Approximately one-third die of the disease and more than one-third have a progressive condition.4 There is no ideal treatment and interventions are reserved for those cases with obstructing symptoms. Surgery, radiotherapy and drugs, including prednisolone and α-interferon, have all been used with varying success.6 There has been a reported overlap in the histopathological appearance and IgG4 status of RD and IgG4-related disease.3 This latter condition is characterized by raised serum IgG4 levels with histological evidence of extensive IgG4+ plasma cells and T-lymphocyte infiltration together with fibrosis.1 The condition is also very responsive to treatment with corticosteroids.2,7 There are emerging manifestations of IgG4-related disease in the lung from inflammatory pseudotumour,7,8 non-specific interstitial pneumonitis and RD.1,3 Our case has the morphological and immunohistochemical appearance of RD with IgG4+ plasma cells, which presented as a pseudotumour. The significance of this specific IgG subgroup is uncertain. However, this does add to the need for further investigations into these 'overlap' conditions and clarification of any diagnostic and/or therapeutic significance. Many thanks to Mr Marc Smith for his help with the photomicrographic images.