Duckworth, Lauren A.

Aims . To identify the most common reasons for consultation to a large specialty breast pathology service at a major institution. To provide insight into the overall challenges in practicing breast pathology. Methods . The anatomic pathology database at one institution was searched for all breast consultations received in 2021, excluding in-house patients and patients who were transferring care. Results . A total of 553 patients met the criteria ( n = 553) from a variety of academic and private practices. For each patient, the paperwork from the submitting institution was reviewed to identify the specific question, and subsequently classified into 14 categories. The reason for the consultation request was not provided for 78 (14%) patients, and a review of the outside diagnoses, where applicable, was performed. In summary, the top 5 reasons for consultation were: (1) assistance with classification of atypical intraductal epithelial proliferations (32%); (2) evaluation for the presence of (micro-)invasive carcinoma (14%); (3) evaluation of fibroepithelial (12%), (4) papillary (11%), and (5) spindle cell lesions (7%). Conclusion . We show an ongoing educational and practice gap for pathologists who most commonly struggle with classifying atypical precursor lesions, specifically when these are small and focal, or bordering on intraductal carcinoma (32%, 177/553). The second most common reason for consultation was classifying invasive carcinomas as microinvasive and subtypes (total of 20.4%, 113/553). As such, our data supports the continued need for rigid and clear criteria for diagnosing threshold lesions (namely atypical hyperplasias) and intraductal carcinoma of the breast.

Introduction: Solitary fibrous tumor (SFT) is a fibroblastic tumor with malignant potential that is underpinned by a recurrent inv12(q13q13)-derived NAB2::STAT6 fusion. Breast and axilla are uncommon locations for this entity. Methods: Records of two academic institutions were electronically searched for breast and axillary SFTs. Clinical and pathologic data were reviewed. Literature review for breast or axillary SFTs was performed. Present study and previously reported tumors were stratified using five SFT risk models: original and modified Demicco metastatic risk, Salas local recurrence risk, Salas metastatic risk, and Thompson local recurrence risk. Results: Five patients with breast or axillary SFT were identified. Median age was 49 years, and median follow-up (available for four patients) was 82 months. Three patients showed no evidence of disease, and one developed recurrence. Literature review identified 58 patients with breast or axillary SFT. Median age was 54 years, and median follow-up (available for 35 patients) was 24 months. Thirty-one patients showed no evidence of disease, three developed recurrence, and one developed metastasis. Original and modified Demicco models and Thompson model showed the highest sensitivity; original and modified Demicco models and Salas metastatic risk model demonstrated the highest specificity. Kaplan–Meier models were used to assess recurrence-free probability (RFP). Original and modified Demicco models predicted RFP when stratified by “low risk” and “moderate/intermediate and high risk” tumor, though sample size was small. Conclusions: While many SFTs of breast and axilla remain indolent, a subset may develop recurrence and rarely metastasize. The modified Demicco risk model demonstrated optimal performance characteristics.