Solitary Fibrous Tumor of the Breast: A Rare Case and its Diagnostic Pitfalls

Solitary fibrous tumors (SFT) are the rare mesenchymal tumors originally described in the pleura. SFT of breast is even rarer and to the best of our knowledge about 35 cases are reported to date, including only six malignant SFT cases.

Casepresentation: 

We report a case of a 52-year-old lady with a large left breast mass involving all the quadrants. The tumor was diagnosed as malignant SFT in a core needle biopsy which was later confirmed on the resection specimen.

Herein, we describe the approach and importance of optimal utilization of immunohistochemistry for diagnosing such rare tumors of the breast, particularly, when clinical presentation, radiology and fine needle aspiration cytology are incongruous.Copyright © 2024. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non-Commercial 4.0International License,which permits copy and redistribution of the material in any medium or format or adapt, remix, transform, and build upon the material for any purpose, except for commercial purposes.INTRODUCTIONThe solitary fibrous tumor is one of the rare mesenchymal origin tumors with an incidence of <0.1/100,000 people.1,2 This tumor tends to pose diagnostic challenges due to similarity in clinical, radiological and histological features with several more common soft tissue tumors like synovial sarcoma, leiomyosarcoma, phyllodes, malignant peripheral nerve sheath tumor (MPNST), etc. The tumor was previously reported to primarily occur in pleura which is still the most common site accounting for 70% of the cases. However, now it is known to occur at any anatomical sites with a varying spectrum of histological features. Histologically, it ranges from hypocellular to hypercellular tumors to anaplastic SFT with sarcomatous transformation.3 Fibroblastic cell is considered as the cell of origin in these tumors. Historically, SFTs are sub-classified into three groups: i) Benign (local disease); ii) not otherwise specified (usually not metastatic); and iii) malignant.4The general criteria adopted for malignant SFTs include a large tumor size, mitotic rate of ≥4/10 high-power fields (HPFs), nuclear pleomorphism, and necrosis. Demiccoet al. proposed a modified four-variable risk stratification model for development of metastasis in solitary fibrous tumors based on age, tumor size, necrosis and mitotic count into three risk classes of low, intermediate, and high risk.5 The diagnosis as well as risk stratification of SFT at unusual sites like the breast are very demanding and not possible on clinical and radiological examination. Accurate diagnosis requires a combined evaluation of clinical, pathological, immunohistochemical and molecular features together. Herein, we report a case of malignant SFT in a 52 year-old lady with a focus on diagnosis.CASE PRESENTATION A 52-year-old lady presented with a progressively enlarging lump in the left breast over the last 12 Case ReportOpen Access