Merkel cell carcinoma: a case report and literature review

Abstract

Merkel cell carcinoma (MCC) is an aggressive cutaneous malignancy of neuroendocrine origin presenting as a painless, rapidly growing nodule. MCC often presents in elderly, fair-skinned individuals in sun-exposed areas. Diagnosis is often overlooked at time of presentation due to its rarity, but MCC is twice as deadly as malignant melanoma. There has been bigger interest in the disease due to increasing incidence and an association with the prevalent virus Merkel cell polyomavirus. This study describes an uncommon presentation of MCC as a right gluteal lesion in an Afro-Panamanian patient. The tumor was suspected to be fibrolipoma, but Immunohistochemistry revealed the diagnosis of MCC, as stains for CD56 and CK20 were positive. In addition to surgical excision, the patient was referred for adjuvant radiotherapy. This case report and literature review elucidates the clinical, histopathologic and management aspects of MCC, which will help in recognizing and treating these tumors.

Figure 1

Microscopic examination reveals nests of monotonous round tumor cells. Tumor cells have scant eosinophilic cytoplasmic rim, round and vesicular nuclei with abundant mitotic figures (HE × 20).

Figure 2

Immunohistochemical stain reveals that tumor cells are positive for synaptophysin (IHC × 20).

Figure 3

Immunohistochemical stain CK20 demonstrated paranuclear dot-like staining (IHC × 20).