Phyllodes tumor of the breast with actin inclusions in stromal cells: Diagnosis by fine-needle aspiration cytology

The occurrence of hyaline inclusions in stromal cells in fibroepithelial tu mors of the breast is very uncommon. These inclusions, characteristic of in fantile digital fibromatosis, are comprised of actin filaments. This report illustrates a case of a benign phyllodes tumor of the breast with inclusio n bodies, identified by fine-needle aspiration. Histologically, many of the stromal cells contained round intracytoplasmic inclusions, with positivity for smooth muscle actin. (C) 2001 Wiley-Liss, Inc.