Granular cell tumour of the pectoral muscle mimicking breast cancer

We describe the case of a 55 year old female who presented with a mass in her right breast. Mammography confirmed a 2 x 2 cm lump, suspicious of malignancy. The lesion was widely resected. Histological examination revealed this to be a benign granular cell tumour.Granular cell tumour is a rare tumour that very occasionally presents within the breast. It is possibly of Schwann cell origin. Clinical features and subsequent investigations may be suggestive of breast malignancy. Tumour cells showing positive immunostaining for S-100 and PAS is in keeping with the diagnosis. Wide local resection is the gold standard treatment.