Granular cell tumor in differential diagnosis of tumors of the breast. The role of fine needle aspiration cytology.

The granular cell tumor (GCT) represents a rare but important lesion in the differential diagnosis of breast tumors. Since this generally benign tumor may be misdiagnosed as malignant in clinical investigation, mammography, sonography, and even in frozen sections, a preoperative diagnosis is of utmost importance. Two cases illustrate that fine needle aspiration cytology (FNAC) may be the method of choice in achieving a correct preoperative diagnosis. The histogenesis of GCT is examined by means of immunohistochemical stainings. The results confirm that this tumor arises from the peripheral nerve tissue. Most likely the Schwann cells and not the nerve cells constitute the origin of GCT.