Eosinophilic and granular cell tumors of the breast

mesenchymal lesions, A granular appearance of the cytoplasm may be caused b y the accumulation of secretory granules, mitochondria, or lysosomes, In th e breast, mucoid carcinomas, carcinomas showing apocrine differentiation, a nd neuroendocrine carcinomas are well known entities, while tumors with onc ocytic and acinic cell differentiation have been only recently recognized, An abundance of lysosomes is characteristic of Schwannian granular cell neo plasms, but smooth muscle cell tumors also may have this cytoplasmic featur e. Awareness of all these possibilities when granular cells are found in br east lesions improves diagnostic accuracy and helps to avoid misdiagnosis o f both benign lesions and malignant tumors. Copyright (C) 1999 by W.B. Saun ders Company.