FINE-NEEDLE ASPIRATES OF GRANULAR-CELL LESIONS OF THE BREAST - REPORTOF 3 CASES, WITH EMPHASIS ON DIFFERENTIAL-DIAGNOSIS AND UTILITY OF IMMUNOSTAINING FOR CD68 (KP1)

Fine-needle aspiration biopsy (FNA) has been recognized as a safe and reliable procedure for evaluating breast lesions. We herein report cyt ologic findings for needle aspirates from three granular cell nodules of the breast. The nodules were detected by diagnostic imaging and ran ged from 0.6 to I cm in diameter. Ultrasound-guided FNA was used in al l cases and revealed cellular aspirates with similar cytomorphologic f eatures consisting of sheets of large granular cells intersected by ar borizing thin-walled blood vessels. The cells had round to oval nuclei , inconspicuous nucleoli, and abundant, often ill-defined granular cyt oplasm. Tissue sections of resected specimens yielded final diagnoses of granular cell metaplasia of histiocytes and stromal cells in one ca se and granular cell tumor (GCT) in the other two cases. FNA smears in all three cases were strongly positive for the lysosomal marker CD68 (KP1) and S-100 protein; therefore, it was not possible to distinguish true GCT from granular cell metaplasia/granular histiocytes. When bre ast aspirates reveal granular cell changes, excisional biopsy should b e done for a definitive diagnosis. (C) 1996 Wiley-Liss, Inc.