A 26-year-old Black woman presented with a palpable left axillary mass. Targeted ultrasound was initially performed demonstrating a 27 × 22 × 28-mm oval hypoechoic mass with indistinct margins and peripheral vascularity (A). Diagnostic mammography demonstrated a round high-density mass with indistinct margins on MLO view (B). Ultrasound-guided biopsy yielded granular cell tumor (GCT). Subsequent MRI for surgical planning (C) demonstrated the GCT in the left axillary tail on postcontrast T1-weighted fat-suppressed (T1FS) imaging (arrow) and revealed an additional GCT in the anterior right breast (curved arrow).
GCTs are generally benign lesions likely of neuroectodermal origin. Most commonly they arise in the tongue followed by skin and the more distal gastrointestinal system.1 Only 5% to 6% of GCTs occur in the breast and are commonly found in the upper inner quadrant. As exemplified above, they most frequently occur in premenopausal Black women but may occur in men.2 Most GCTs are solitary lesions but may be multiple. The incidence of multiple tumors is 5.4% to 17.6%.1,2
Mammography and ultrasound are the primary imaging modalities used to evaluate GCTs of the breast. Mammography findings are nonspecific and range from round, circumscribed masses to spiculated masses with poorly defined margins. Ultrasound findings are similarly variable ranging from benign-appearing circumscribed solid masses resembling fibroadenomas to malignant appearing masses with indistinct margins and posterior shadowing.2 GCTs lack a capsule, allowing them to appear grossly infiltrative.
The concerning imaging features of GCTs frequently lead to core biopsy. After diagnosis, preferred treatment is surgery with negative margins to decrease the chance of local recurrence. Chemotherapy and radiation therapy have not been shown effective for GCTs.
Irby G, Zamora K. JAOCR at the Viewbox: Multiple Granular Cell Tumors. J Am Osteopath Coll Radiol. 2021;10(1):42.
Glenn Irby is with the The University of Alabama at Birmingham School of Medicine, Birmingham, AL, Dr. Zamora is with the Department of Radiology, The University of Alabama at Birmingham, Birmingham, AL.