PMC4079032_01
Low-magnification photomicrograph showing superficial malignant melanoma in confluence with an underlying spindle cell proliferation exhibiting "neuroid" features (hematoxylin and eosin, x20).
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F1
Histologically, a biphasic tumor was observed consisting of malignant melanoma overlying and in close approximation with a very mature-appearing neural component (Fig. 1).
High-magnification photomicrograph showing nests of malignant melanoma cells that seem to float on a fairly well-differentiated background of more eosinophilic spindled cells with a "neuroid" appearance and associated lymphocytepredominant inflammation (hematoxylin and eosin, x200).
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F2
Rare nests of melanoma cells were observed within this rather mature neural component and were contiguous with the overlying dermal melanoma cells (Fig. 2).
High-magnification photomicrograph revealed an increase in atypical mitoses and more marked cytological atypia within the neurotized component (hematoxylin and eosin, x600).
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F3
Despite the overall mature appearance of the neural component, focal areas showed atypical cells and numerous mitoses in neural-appearing cells (Fig. 3).
S-100 strongly highlights both the superficial conventional melanoma and the underlying associated neurotized component (immunohistochemistry, x40).
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F4
Immunohistochemical stains showed the neurotized component diffusely/strongly positive for S-100, vimentin, and NSE and focally positive for SOX10 (approximately 50% of lesional spindled cells) and MITF but negative for Melan-A (Figs. 4, 5). In contrast, the typical melanoma component was strongly positive for Melan-A, SOX10, and MITF and showed similar positive staining for S-100, vimentin, and NSE (Fig. 4).
Immunohistochemical characteristics of the neurotized tumor component. A, S-100 strongly highlights the neurotized component (immunohistochemistry, x400). B, NSE is positive in the neurotized component (immunohistochemistry, x400). C, SOX10 is focally positive (approximately 50% of lesional cells staining) within the neurotized component (immunohistochemistry, x400). D, HMB-45 is negative within the neurotized component (immunohistochemistry, x400). E, Neurofilament is negative within the neurotized component (immunohistochemistry, x400). F, EMA is negative within the neurotized component (immunohistochemistry, x400).
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F5
Immunohistochemical stains showed the neurotized component diffusely/strongly positive for S-100, vimentin, and NSE and focally positive for SOX10 (approximately 50% of lesional spindled cells) and MITF but negative for Melan-A (Figs. 4, 5). Stains for EMA and neurofilament were negative within the neurotized component (Fig. 5) (see also Table 1).