Abstract
Background : Malignant melanoma of the paranasal sinuses is a rare entity. This report describes a case of malignant melanoma of a paranasal sinus with malignant pleural effusion, including the cytological and histopathological findings.
Case : A 72-year-old woman presented with a chief complaint of nose bleeds. A CT scan showed a left paranasal sinus mass with invasion of the left orbit and base of the skull. A biopsy specimen of the left paranasal sinus tumor revealed epithelioid cells in the epithelium and subepithelium, and some of the tumor cells contained melanin granules. The patient later developed dyspnea due to a massive left pleural effusion. Cytology of the left pleural effusion revealed the presence of round tumor cells in small clusters or individually dispersed against a bloody background. The tumor cell nuclei were large and vesicular and contained prominent eosinophilic nucleoli, but no melanin pigment was visible in the tumor cell cytoplasm. Immunocytochemically, the tumor cells were positive for melan A (MART-1), PNL2 (melanoma), HMB45, and S100 protein. The cytological diagnosis of the left pleural effusion was metastatic malignant melanoma.
Conclusion : The differential diagnosis in this case included malignant mesothelioma and metastatic carcinoma, because there were no melanin granules in the tumor cells in the malignant pleural effusion. Immunocytochemical staining was useful in making the cytological diagnosis in this case.
