Carcinoid : Nuclear Features
Carcinoid tumor cells are polygonal in shape with a uniform monomorphic appearance and moderate quantity of granular eosinophilic cytoplasm. The nuclei are round or oval with finely dispersed granular chromatin (salt and pepper appearance) and inconspicuous or punctate nucleoli . Occasional foci with highly pleomorphic nuclei (not accompanied by necrosis or increased mitoses), multinucleated cells, or prominent nucleoli may be present. Mitotic activity is low (less than 2 mitoses per 10HPF or 2 sq.mm). Rare cases are composed predominantly of oncocytic or clear cells or may contain abundant melanin.