Spindle cell lesions of the breast: diagnostic issues

Abstract

Spindle cell lesions of the breast encompass a broad spectrum of entities. In addition to breast-specific spindle cell lesions, soft tissue and cutaneous spindle cell lesions can also present in the breast. The prognosis and proper management of each entity varies considerably and thus calls for a systemic approach in diagnosis. A simple two-step approach is described in this review, where spindle cell lesions are classified into biphasic (with both spindle and epithelial components) and monophasic (spindle cell only) types, followed by histologic grading. This diagnostic algorithm is easy to use and adequately reflects the pathogenesis and clinical behavior of the entities. When supplemented by careful histologic examination and judicious use of immunostains, this algorithm will aid in the correct labeling of most spindle cell lesions of the breast.