ABSTRACT
This chapter provides an uncommon but understanding the histology report and interpretation of the findings, including areas of diagnostic uncertainty, is a necessary skill for all clinicians involved in the management of these patients. Histological assessment of tumours is required for diagnosis and allows relevant prognostic factors to be identified. Merkel cell carcinoma (MCC), or primary neuroendocrine carcinoma of the skin, is less common than other non-melanoma skin cancers. It is more common in patients who are immunosuppressed. MCC can be associated with other cutaneous malignancies, for example, chronic lymphocytic leukaemia and squamous cell carcinoma. The cell nuclei typically have granular or stippled chromatin which is commonly described as having a ‘salt and pepper' appearance. The presence of dense core neuroendocrine granules is confirmed by expression of chromogranin, synaptophysin, neurofilament and CD56 proteins. Once a diagnosis of MCC has been confirmed, further parameters are assessed to allow staging, guide management and inform prognosis.
