Solitary intramammary schwannoma mimicking phylloides tumor: Cytological clues in the diagnosis
A 30-year-old lady presented to the surgical outpatient department with complaints of a slow growing painless lump in right breast of ten years duration. On examination, a huge exophytic, firm, non-tender mass, measuring about 15 cm × 12 cm was seen occupying the upper inner quadrant of right breast []. However, there were no skin changes or axillary lymphadenopathy. A clinical diagnosis of phylloides tumor was made and the patient was subjected to fine needle aspiration cytology study. A 21 gauge needle was used and aspiration was performed from multiple sites. The smears were stained with hematoxylin and eosin and examined. The smears were cellular, composed of spindle shaped cells in clusters and singles, with scant cytoplasm, elongated vesicular, mildly pleomorphic nuclei; the background showed myxoid material []. Ductal epithelial elements were characteristically absent. Occasional presence of structures resembling verocay bodies with nuclear palisades, separated by fibrillar material was observed []. A cytological diagnosis of benign spindle cell tumor, favoring schwannoma was made. A differential diagnosis of phylloides tumor was also given because of the site, clinical features and the possibility of unsampled epithelial elements in a stroma predominant phylloides. The patient underwent lumpectomy.\nThe excised specimen was a skin covered lobulated mass measuring 15 cm × 11 cm × 6 cm with a solid, grey-white, and fleshy cut surface. Microscopic examination showed an encapsulated, predominantly cellular tumor composed of spindle shaped cells arranged in interlacing fascicles and whorls. Focal areas showed palisading of nuclei with intervening fibrillary cytoplasm resulting in verocay body formation []. Hypocellular myxoid areas with dilated blood vessels were seen merging with the cellular areas imperceptibly. Epithelial elements were not seen within the lesion, even after extensive sampling. Immunohistochemical staining with S-100 protein yielded strong and diffuse positivity of the tumor cells and the epithelial markers such as cytokeratin and EMA were negative. A final diagnosis of intramammary schwannoma was made.