Gynecomastia demonstrated on the bone scan.

Bone scans with 99mtechnetium diphosphonate were performed on 2 patients with gynecomastia induced by diethylstilbestrol therapy for adenocarcinoma of the prostate. Neither patient had evidence of bone metastases but both scans revealed increased isotope concentration over the anterior rib cage at the lateral margin of the chest wall, corresponding in location to the hypertrophic breasts. This observation may be related to similar radionuclide uptake in normal and abnormal female breasts. One should not mistake the finding of gynecomastia for metastases of the ribs.