Benign macro-orchidism in a pubescent boy.

We report on a 12 1/2-year-old boy with bilateral testicular enlargement. After an extensive evaluation we eliminated precocious puberty, hypothyroidism, congenital adrenal hyperplasia, X-linked mental retardation and bilateral malignant testicular neoplasms from consideration. Diagnosis was benign macro-orchidism. The clinical and laboratory features of this condition are sufficiently distinct from the other causes of testicular enlargement to allow a diagnosis to be made without testicular biopsy or orchiectomy.