Merkel cell carcinoma
Merkel cell carcinoma
A highly aggressive skin tumour, usually of the head and neck, which is most common in the elderly, and 13-fold more common in patients with HIV-1. Merkel cell polyomavirus is clonally integrated at various sites in the genome of most Merkel cell carcinomas.Associations
Actinic keratoses, Bowen's disease, squamous cell carcinoma, basal cell carcinoma.
DiffDx
Small blue-cell tumours—e.g., leukaemia, acute lymphoblastic lymphoma, granulocytic sarcoma, NK/T-cell lymphoma, and metastatic small cell carcinoma from the lung or elsewhere.
Prognosis
3-year survival: 68% female, 36% male.
Poor prognosticators
> 30 mm tumour, stage II+, lack of inflammation, Ki-67 (cell proliferation) index of > 50%.
Management
Wide excision, prophylactic lymph node dissection, radiation therapy, chemotherapy.