engleski

Metastatic melanoma in parotid gland: Case Report

Background: Primary melanomas of parotid gland are rare since the majority of reported cases represent melanoma metastasis from the skin of head and neck area. Case: A 32-year-old male was presented with a two- month, painless swelling, located to the angle of the left mandible. Ultrasound (US) revealed a parotid gland with a nodule 23 mm in the greatest diameter. US-guided fine-needle aspiration (FNA) was performed and showed numerous lymphatic cells and few single pleomorphic cells with coarse chromatin and prominent nucleoli. The intranuclear cytoplasmic inclusions were found in some cells as well as intracytoplasmic brown pigment. The cytological diagnosis of poorly differentiated malignant tumor was made and surgical treatment was recommended. A total parotidectomy was performed and the tumour with partial involvement of intraparotid lymph nodes was revealed. Microscopically, tumour was consisted by polymorphic, mostly spindle neoplastic cells with eosinophilic cytoplasm, intranuclear inclusions and few cells with brown pigment. Immunohistochemically, neoplastic cells showed reactivity for S-100 protein and vimentin and focally reactivity for microphthalmia transcription factor (MiTF). CK AE1/AE3, CK 7, CK 20, desmin, HMB45, Melan-A, CD 10 and tyrosinase were negative. Histopathological diagnosis implied metastatic melanoma but there was no data about existence of of primary tumour so even renal cell carcinoma was considered at differential diagnosis. After finding of nevus operation 5 years ago, revision of histological slides was recommended. Following revision of two pathologists, the diagnosis was melanoma (pT2a). Conclusion: In conclusion, differential diagnoses of polymorphic type of malignant tumour present confusing diagnostic challenges especially in those melanomas that express aberrant antigenic profiles. When parotid mass appears, the history of the patient should be checked carefully.

Parotid gland ; Melanoma ; FNA cytology

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