[Importance of the exhaustive anamnesis to an unexplained unilateral gynecomastia in a child].

Gynecomastia consists of breast enlargement due to a hormonal imbalance between estrogens and androgens. Unilateral and important breast growth requires ruling underlying pathologic disorders out. Mechanical cause is uncommon, causing enlargement by repeated stimulation. We report a 6-year-old boy with unilateral gynecomastia. Hyperprolactinemia is the only abnormal finding at laboratory tests. After repeated inquiries, a continuous breast selfstimulation is detected. Its relation with gynecomastia is verified because prolactin normalizes and breast regressed in further revisions, after stopping stimulus.