PMC4336382_01
Histopathological examination showing dense infiltrate of small tumour cells with hyperchromatic nuclei and little cytoplasm. (A) Haematoxylin-eosin, magnification 20x. (B) Haematoxylin-eosin, magnification 400x.
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An incisional biopsy was performed and histology showed a dense infiltrate of small tumour cells with hyperchromatic nuclei and little cytoplasm (Fig. 1).
Positive immunostaining for cytokeratin 20 showing a dot-like pattern (magnification 400x).
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Immunohistochemistry confirmed the diagnosis of MCC, with positive staining for cytokeratin 20 (CK20) (Fig. 2), neuron-specific enolase (Fig. 3), synaptophysin and negative staining for cytokeratin 5/6T,
(A and B) Spontaneous regression of Merkel cell carcinoma after incisional biopsy.
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TTF1 and MelanA. The patient attended for an excision 8 weeks after her initial biopsy and showed no presence of lump prior to excision (Fig. 4).