[A misleading breast tumor: a granular cell tumor of the breast].

Granular cell tumours are rare benign neoplasms, that occur infrequently in the vulva or the breast. Two cases of the tumour occurring in the breast observed personally are reported. Emphasis is laid on the clinical radiological and macroscopic aspects of this tumour that can mimic carcinoma of the breast. It is best to carry out frozen section histological examination because this is the only way to make a correct diagnosis. Positive immunohistological staining for S-100 protein which is also found in Schwann cells shows that it may be of neural origin for such lesions. The ultrastructure suggests the same origin. The only treatment should be wide local excision with the frozen section making it possible to avoid more radical surgery. Long term observation should be carried out when the excision is near the tumour because there is a high risk of recurrence if that occurs.