FINE-NEEDLE ASPIRATION CYTOLOGY PRESENTATION OF A CELLULAR VARIANT OFBREAST MYOFIBROBLASTOMA - REPORT OF A CASE WITH IMMUNOHISTOCHEMICAL STUDIES

BACKGROUND: Myofibroblastoma is a benign stromal tumor of the breast t hat occurs mainly in males. There are few reports on the cytologic asp ects of breast myofibroblastoma, all of them corresponding to the clas sic type. Recently, some variants of myofibroblastoma were histologica lly described as: collagenized, epithelioid, cellular and infiltrant. Presently, the variant forms of myofibroblastoma have not been well ch aracterized pathologically or clinically. CASE: A case of a cellular v ariant of myofibroblastoma was diagnosed by fine needle aspiration in a 68-year-old male. The aspirates consisted of highly cellular, cohesi ve groups of randomly arranged, plump oval and spindle cells. The nucl ei had fine, uniformly distributed chromatin with inconspicuous nucleo li, and mild pleomorphism was observed. The cytoplasm teas scant, with ill-defined borders. We did not observe epithelial components, inflam matory cells or collagenous stroma. Histologic examination showed a de nse proliferation of interlacing, spindle-shaped neoplastic cells, wit h some nuclear atypia. Conspicuous collagen bands were present only fo cally in the tumor. The margins of the specimen were free, but the tum or had infiltrative borders microscopically. The spindle cells showed immunoreactivity for vimentin, desmin, muscle-specific actin and CD 34 . CONCLUSION: Our case of a cellular variant of myofibroblastoma of th e breast with expression of CD 34 adds move one benign spindle cell le sion of the breast that should be considered among the diagnostic poss ibilities for aspirates from this group of lesions.