Granular Cell Tumor of the Breast: Clinical Presentation, Pathological Diagnosis and Treatment

Introduction: Granular cell tumor is a rare neoplasm of soft tissue and only in 1% of cases, it can shows a malignant behaviour. It is presumed to be a tumor originating from perineural or putative Schwann cells of peripheral nerves. Materials and Methods: We reviewed five patients affected by Granular cell tumor of the breast treated between January 2011 and January 2021 at the Fondazione Policlinico Universitario Agostino Gemelli IRCCS of Rome, Italy. Results: All of the granular cell tumors presented as solitary, painless and firm lump, highly suggestive of malignancy. The radiological findings were heterogeneous and non-specific. All lesions presented as masses, more clearly evident on ultrasound as hypoechoic lesions, with irregular shape, blurred contours and borderline features. The tumors were composed of large polygonal cells with abundant eosinophilic granular cytoplasm and small, central nuclei, being immunohistochemically positive for S100, Vimentin (with variable staining), CD56; negative for HMB45, MelanA, AE1/AE3, EMA, and Desmin. Conclusion: Granular cell tumor is a rare, usually benign breast disease that can have very similar characteristics to breast cancer both clinically and radiologically. Treatment of choice consists in wide resection or lumpectomy with margin assessment (no ink on tumor).