PMON325 Rare Presentation of Precocious Puberty Secondary to LH-Secreting Adenoma

BACKGROUND: Normal male puberty begins after 9 years of age with a concurrent rise in luteinizing hormone (LH) and follicle-stimulating hormone (FSH). These play distinct roles, with LH acting on Leydig cells to stimulate testosterone and secondary sex characteristics, while FSH promotes testicular growth by stimulating the maturation of seminiferous tubules. CLINICAL CASE: An 8-year 9-month-old male TV presented with a 1.5 year history of facial hair and 9 months of phallic growth, body odor and acne. Physical exam revealed phallic enlargement, Tanner stage I pubic hair and firm, borderline pubertal testes (4 cc bilaterally). Bone age was 9 years at a chronological age of 8 years 6 months. Laboratory evaluation was inconsistent with typical puberty – LH (9 mIU/mL, RR 0.0-0.3 mIU/mL) and testosterone (519 ng/dL, RR 2-8 ng/dL) were elevated while FSH was pre-pubertal (<0.1 mIU/mL, RR 0.0-2.8 mIU/mL) and androgens were only mildly elevated (androstenedione 0.363 ng/mL, RR 0.03-0.3; 17-OHP 155 ng/dL, RR<63 ng/dL). Head MRI revealed an anterior pituitary adenoma measuring 8×12×10 mm. After failing to respond to leuprolide, TV was initiated on spironolactone and anastrozole to minimize pubertal progression prior to transsphenoidal adenomectomy. Surgical pathology was positive for steroidogenic factor 1 but negative for LH, FSH and thyroid-stimulating hormone immunoreactivity. However, he had post-operative reduction of LH (0.4 mIU/mL, RR 0.0-0.3 mIU/mL) and testosterone (16 ng/dL, RR 2-8 ng/dL). CONCLUSIONS: Normal male puberty follows a predictable sequence, beginning with testicular enlargement followed by body odor, pubic hair growth, phallic enlargement, voice change, and increased growth velocity. In TV, hypersecretion of LH led to testosterone production, causing secondary sex characteristics. However, his pre-pubertal FSH did not stimulate the testicular growth that typically heralds the onset of puberty. Digression from typical pubertal sequence and isolated high LH raised concern for a pathologic cause. Central precocious puberty (CPP) is most often idiopathic in females, although more commonly associated with CNS lesions in males. Rarely, precocious puberty results from a functioning gonadotroph adenoma. Less than 1% of these are hormonally active. If active, these more often secrete FSH or co-secrete FSH and LH, and typically require surgical resection given limited success of medical therapies. This case illustrates the distinct roles of FSH and LH in pubertal development. Departures from the typical sequence of development should expand one's differential to include etiologies resulting in nonconcurrent secretion of gonadotropins. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m.