A tumour, a cell, a misunderstanding: trabecular (Merkel cell) carcinoma of the skin

Trabecular carcinoma has been renamed as Merkel cell carcinoma because, ultrastructurally, tumour cells resemble Merkel cells of the skin. Recently, evidence of exocrine (sweat gland) differentiation in some trabecular carcinomas has been reported. These findings raise two possibilities: (1) trabecular carcinomas are a heterogeneous group of lesions; or (2) that trabecular carcinomas are glandular tumours, in which exocrine features are rarely detected.