Testotoxicosis with an Episodic Course: An Unusual Case Within a Series

ABSTRACT Objective: To describe an unusual case of familial male precocious puberty (FMPP) characterized by periodic remission compared to a series of boys with typical testotoxicosis. Methods: Medical records of boys with FMPP followed at our institution from 2001–2017 were reviewed. Variables analyzed included age, family history, physical exam, hormone levels, bone age, and treatment. Results: A boy of age 2 years 10 months presented with growth acceleration and masturbatory behaviors. On exam, he had 6-mL testes, an enlarged phallus (10.5 × 2.5 cm), and Tanner 2 pubic hair. Testosterone was 242 ng/dL (normal level, ≤30 ng/dL). Genetic testing revealed an Asp578Gly luteinizing hormone receptor mutation confirming FMPP. Anastrozole 1 mg and bicalutamide 50 mg daily were started. During 7.5 years of follow-up, two periods of spontaneous remission occurred lasting >3 years and 10 months, respectively. Both were characterized by prepubertal testosterone levels (10 to 28 ng/dL) and arrested pubertal development off therapy. Relapses were marked by elevated testosterone, growth acceleration, and pubertal progression. Ten additional boys aged 3.46±0.72 years with FMPP were identified, one of whom also had an Asp578Gly mutation. Average testosterone at presentation was 335 ± 193 ng/dL (range, 146 to 778 ng/dL) and average bone age/chronologic age was 2.02 ± 0.47. All were treated with bicalutamide and anastrozole or letrozole. Conclusion: We report a case of intermittent FMPP in contrast to a series of boys with a characteristic clinical course. To our knowledge, a similar case has not previously been reported. Our case expands the clinical spectrum of this rare condition. Abbreviations: BA bone age FMPP familial male precocious puberty LH luteinizing hormone PP precocious puberty