Spindle Cell Lesions of the Breast: A 12-Year Experience

Breast spindle cell lesions (BrSCL) are rare pathologies encompassing a wide range of conditions, from benign reactive processes to aggressive malignancies. Their diverse and overlapping clinical, radiological and histological features pose significant diagnostic challenges. This study examines the clinical, radiological and histological characteristics of BrSCL to improve diagnostic accuracy and inform management strategies.

This retrospective, single-centre cohort study included all cases of BrSCL identified on core biopsy from 2008 to 2020, excluding fibroepithelial lesions and metaplastic cancers. It examined clinical presentations, imaging findings, formal excisional pathology and clinical outcomes.

Thirty cases were analysed, with 70% (n = 21) presenting due to breast symptoms and 30% (n = 9) detected through breast screening or incidentally. Eligible cases were histologically subdivided into atypical (ASCL) (n = 10) and bland (BSCL) (n = 20) spindle cell lesion groups. Following formal excision, 80% of ASCLs were malignant (sarcoma: n = 1; malignant phyllodes tumour: n = 3; metaplastic cancer: n = 4), whilst 20% (n = 2) were benign. Eleven BSCLs underwent excisional biopsy, with no malignancy found (benign: n = 10; no lesion: n = 1). Nine patients underwent radiological and clinical surveillance.

BrSCLs are rare and diagnostically complex entities. Lesions detected on core biopsy with features of ASCL carry a high risk of malignancy and should undergo surgical excision. In contrast, BSCL from core biopsy are frequently benign and those demonstrating low-risk imaging features and benign core biopsy findings may be considered for surveillance. A multidisciplinary approach is essential for optimising outcomes in this challenging and uncommon subset of breast pathology.