Melanoma metastases: brain and spine

There is a large nodular hyperdense well-defined right parietal mass surrounded by vasogenic oedema and promoting local mass effect with compression of the posterior horn of the right lateral ventricle. The lesion shows a peripheric and irregular enhancement. Other two small similar lesions are identified in the left frontal lobe and in the inferior aspect of the left cerebellar lobe. 

MRI images show a sacral mass involving the left foramina at S2 and S3 levels and compressing the respective nerve roots. The mass is T1 hypointense and demonstrates a heterogeneous peripheral contrast enhancement which delineates a probable necrotic center. 

MICROSCOPIC DESCRIPTION: 1&2. Paraffin sections show fragments of a densely hypercellular tumour. Tumour cells have markedly pleomorphic round oval and angulated vesicular nuclei many with conspicuous nucleoli and a variable amount of pale cytoplasm. The cytoplasm of scattered cells contains finely granular and globular black/brown pigment. Frequent mitotic figures are identified and there are several foci of tumour necrosis. Tumour is sharply demarcated from a narrow rim of adjacent included brain parenchyma. Immunohistochemistry shows strong nuclear staining for SOX-10 in >90% of tumour cells. No staining for tyrosinase, melan A, HMB-45, GFAP, TTF-1, BER-Ep4, or cytokeratins (AE1/AE3, CK20, CK7) is seen in tumour cells. The features are of metastatic malignant melanoma. DIAGNOSIS: 1&2. Parieto-occipital brain tumour: Metastatic malignant melanoma.