PMC5379819_01
(a) Cutaneous melanocytic lesion involving the head and neck. (b) CT scans show evidence of bleeding in the right frontal lobe with marked perilesional edema. (c) Obliteration of ipsilateral lateral ventricle with mild dilatation of the contralateral one. (d) On T1WI, the lesion is heterogeneously hyperintense. (e) On T2WI, lesion appears intensly hypointense. (f) Coronal post contrast film shows peripheral but intense contrast enhancement with broad falcine attachment
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F1
There were a few small hairy nevi situated in the region of the left angle of the mandible [Figure 1a]. Effacement of the ipsilateral lateral ventricle was observed with mild dilatation of the ventricles [Figure 1b and c]. T1 hyper intense and intensely T2 hypointense with blooming on the SWAN sequence indicating the presence of hemorrhage within the lesion [Figure 1d and e]. The lesion showed minimal peripheral contrast enhancement and marked perilesional edema (Grade II) with a midline shift of approximately 1.3 cm to the left. A dural attachment was also noted to the falx [Figure 1f].
(a) Diffuse melanosis involving the pia-arachnoid and the brain is seen to be tense, (b) Surgical cavity made after total removal of mass, (c) Postoperative scan shows complete excision of the mass
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F2
On opening the dura, the brain appeared tense and there was diffuse dark pigmentation of the exposed leptomeninges [Figure 2a]. The blood clot was evacuated from within the lesion, and gross total tumour decompression was achieved [Figure 2b and c].
(a) Tumor composed of tumor cells arranged in sheets displaying polygonal cells having round vesicular nuclei, small eosinophilic nucleoli, and moderate amount of cytoplasm containing abundant melanin pigment. Mitotic figures are occasional (H and E x400), (b) Tumor and adjoining brain showing tumor cells infiltration into the adjacent brain parenchyma (H and E x100), (c) Melanin pigment got bleached with potassium permagnate (Bleach x200), (d) Black pigmentation shown by Masson Fontana (Masson Fontana x200)
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F3
Mitotic figures were occasional with no necrosis [Figure 3a-d].
On immunohistochemistry tumor cells show positivity for: (a) Vimentin (x400), (b) HMB-45 (x400), (c) S-100 (x400) and (d) Ki67 <2% (x100)
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F4
Immunohistochemistry (IHC) was positive for HMB-45, vimentin, and S-100 with no epithelial membrane antigen; Ki-67 index was 1-2% [Figure 4a-d].