[P-17] Primary malignant melanoma of the lung: a case report of a very rare neoplasm occurring in young patient

Thu D.A. Phan and Tung D. Luu

Department of Pathology, Faculty of Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam

Background: Primary malignant melanoma of the lung (PMML) is rare, with limited published reports. This case report discussed the diagnosis and management of a PMML occurring in a young patient and reviewed existing literature.

Case Presentation: A 35-year-old male patient incidentally detected a tumour along the left aspect of the pericardium on X-rays without any symptoms. CT scan showed a well-circumscribed and lobulated tumour in the middle mediastinum with 7 x 4.5 x 4 cm. No other lesions were detected. The neoplasm consisted of polygonal cells with clear cytoplasm, atypical nuclear, melanin deposits and haemosiderin-laden macrophages. Tumour cells showed strong positivity of HMB45 and vimentin but no reaction with CK, actin, CD34 and synaptophysin. Morphology and immunohistochemical findings were consistent with malignant melanoma of the lung.

Discussion and Conclusion: Primary melanoma in the lung is sporadic and can mimic lung cancer clinically and pathologically. If the tumour is amelanotic, the diagnosis is challenging and easily misdiagnosed as other lung carcinomas. HMB45 and vimentin are helpful to diagnose such immunophenotypic variations of melanoma.