A case of familial male-limited precocious puberty in a 4-year-old boy

Abstract

Familial male-limited precocious puberty (FMPP), or testotoxicosis, is a rare cause of precocious puberty in males. It is caused by an activating mutation in the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) gene. This causes excessive production of testosterone, with LH and FSH levels suppressed. Generally, boys present with signs of puberty, with age of onset between 2-5 years essentially with penis and testes growth, linear growth acceleration and progressive bone age advancement. Differential diagnosis is often a challenge with others causes of peripheral puberty. The goal of treatment is to decrease the effect of testosterone as well as reduce the conversion of testosterone to estrogen. The long-term aims are to prevent precocious virilization and to delay closure of the epiphyseal plates to maintain adult height potential. Little is known about the long-term effects of treatment because the disorder is so rare. However recent studies using bicalutamide and anastrozole have been promising. In this report, we present a boy with FMPP with a classic mutation in the LHCGR gene, who has been challenging to manage with off-label drugs.

Keywords

• precocious puberty, testotoxicosis, familial male-limited precocious puberty, antiandrogen, ketoconazole, letrozole