Spindle Cell Lesions of the Breast on Fine-Needle Aspiration Biopsy: A Miscellany of Masses

Abstract

A variety of primary breast and metastatic lesions to the breast can present with spindle cell cytomorphology. These lesions may range from benign reactive or inflammatory lesions to high-grade malignancies. Spindle cell lesions of the breast are not often seen on fine-needle aspiration biopsy (FNAB) but need to be correctly managed when they are encountered. While mesenchymal lesions of the breast have a spindle morphology, lesions derived from the epithelium and myoepithelium can be spindled as well. By assessing if the lesion comprises spindle cells only or if other components such as epithelial cells are apparent and then determining whether the spindle cells appear bland or pleomorphic, together with close clinicoradiologic correlation and prudent use of ancillary tests, a variety of lesions can be diagnosed on FNAB. However, core needle biopsy or excision biopsy may be required in some patients. The cytomorphology, ancillary studies, and clinicoradiologic findings of a range of spindle cell lesions of the breast are further discussed.

A case report of a mammary myofibroblastoma in a male and literature review of radiologic and pathologic features of breast myofibroblastoma

“…Myofibroblastoma of the breast can be suspected preoperatively using FNAC. The cytological clues include oval to spindle‐shaped cells arranged randomly in a variable myxoid collagen matrix, extended slightly moderately cellular, fascicular clusters, naked ovoid nuclei, scant cytological atypia, nuclear groove, and intranuclear pseudoinclusions, absence of epithelial elements and absence of mitosis and necrosis . Our case demonstrated the same features in FNAC including spindle cells with arranged single and clustered benign spindle‐shaped mesenchymal cells with a finely granular chromatin pattern and with no signs of pleomorphism, mitotic activity, and epithelial component.…”

“…In immunohistochemistry, myofibroblastoma stains positively for Vimentin, Desmin, and CD34. Positively stained with estrogen, progesterone, androgen receptors, SMA, S100, bcl‐2 and negatively for CD31, and cytokeratin are detected in some types of myofibroblastoma …”

“…Positively stained with estrogen, progesterone, androgen receptors, SMA, S100, bcl-2 and negatively for CD31, and cytokeratin are detected in some types of myofibroblastoma. 24 Myofibroblastoma can show different variants using histological patterns. Variants identified included classic, cellular, collagenous/fibrous, lipomatous, infiltrative, myxoid, epithelioid, and decidua-like variants.…”

MED12,TERTandRARAin fibroepithelial tumours of the breast

“…Unfortunately, while criteria for PT grading appear simple and clear-cut, their actual application can be challenging, sometimes resulting in differing grades assigned when assessed by different histopathologists. In addition, PTs can often present similar histology not only to fibroadenomas7 8 but also to other spindle cell neoplasms of the breast 8–10. Over recent decades, much interest has been generated in the genetic and molecular pathogenesis of fibroepithelial tumours, in the hopes of understanding their formation and progression, leading to the identification of genomic abnormalities that may serve as diagnostic adjuncts.…”