A Rare Case of Precocious Puberty Secondary to an LH-secreting Pituitary Adenoma

An 8-year, 7-month-old male presented with puberty symptoms, including a 1.5-year history of facial hair with 9 months of phallic growth, body odor, and acne. Physical examination revealed phallic enlargement but only 4 mL testes bilaterally. Laboratory evaluation revealed markedly elevated LH and testosterone, but a prepubertal FSH level and minimally elevated adrenal androgens. A magnetic resonance imaging scan of the head revealed an anterior pituitary adenoma, and after the patient failed to respond to leuprolide, he was initiated on spironolactone and anastrozole to minimize pubertal progression before transsphenoidal adenomectomy. Postoperatively, the patient had rapid reduction of LH and testosterone, with subsequent cessation of pubertal progression, confirming the diagnosis of an LH-secreting pituitary adenoma despite negative immunoreactivity for LH and FSH. Functioning gonadotroph adenomas are rare and have been documented only in small case series and case reports. When active, these most commonly secrete FSH or co-secrete FSH and LH, and only very rarely result in precocious puberty. Here, we describe a rare case of an isolated LH-secreting functioning gonadotroph adenoma resulting in precocious puberty. This case reinforces the need to critically analyze departures from the typical pubertal sequence and to expand one's differential to include etiologies that can cause unbalanced secretion of gonadotropins.