To investigate the clinicopathological and immunohistochemical features, diagnosis and prognosis of granular cell tumor of breast (GCT) and to improve the awareness of the disease.

Three cases of GCT were collected; Specimens were fully drawn, microscopic pathologic examinations and immunohistochemistry (SP method) were performed.

Three cases were female patients aged from 39 to 56 years old (average 46 years) . In clinical, a single indolent or indolent mass with a hard texture was located in the breast parenchyma. In pathological, the lump was mainly solid or hard tumor with clear boundary or infiltration, with a mean diameter of 2.1 (1.2-3.0) cm, and grey to yellow sections. Histologically, large cells were round or polygonal in shape. The cytoplasm was abundant and eosinophilic. The boundary of the tumor was clear in one case, and in the other two cases, the boundary was unclear. The nucleus was small and located in the center or ectopic. The cytoplasm was coarse-grained with s-100 staining positive microparticles and PAS reaction positive (anti-digestive enzymes) . Immunohistochemistrically, the tumor cells were strongly positive for S-100, CD56, NSE and Vimentin, and negative for CK and SMA. None of the patients had present malignant transformation or metastasis.

GCT can occur in any part of the body, but is not common in breast. GCT is similar to breast cancer in clinical manifestations, imaging and macroscopic observation, etc. The correct diagnosis of this lesion depends on HE morphology, immunohistochemistry and special dyeing. The close postoperative follow-up should be performed.

Breast neoplasm; Secretory carcinoma; Immunohistochemistry; PAS