Perianal hair as an unusual presentation of non-classical congenital adrenal hyperplasia.

To cite: Gopal-Kothandapani JS, Petkar A, O’Shea E, et al. BMJ Case Rep Published online: [please include Day Month Year] doi:10.1136/ bcr-2013-010123 DESCRIPTION A 6-year-old girl was referred with a 1 year history of ‘strings in her bottom’. Her parents were unrelated and white Caucasian. Pregnancy and birth history were unremarkable. Postnatal examination had shown normal female genitalia. At referral, her height was on the 50th centile, while her weight was on the 98th centile. Her blood pressure was normal. She did not have excessive skin or mucosal pigmentation. In the assessment of puberty, there was no breast development. Two dark hairs were present over the labia majora, but none were noted over the mons pubis. The clitoris was marginally enlarged, but there was no posterior labial fusion. Long, dark and coarse hairs were noted in the perianal area, with perineal extension (figure 1). Axillary hairs were not present. Endocrine investigations revealed suboptimal cortisol levels (403 nmol/L) to stimulation, with peak 17-OH progesterone >100 nmol/L, suggesting the diagnosis of 21 hydroxylase congenital adrenal hyperplasia (CAH), with no evidence for salt loss. Genetic testing showed heterozygous mutations (c.290-13C>G and c.814G>T) in CYP21A2, with normal gene copy number, confirming the diagnosis of non-classical CAH. Oral hydrocortisone was started on the basis of a history of lethargy and suboptimal cortisol to stimulation. Children with non-classical CAH usually present with pubic hair and enlarging clitoris owing to androgen excess. Perianal hair has not been reported as a presenting feature in this condition. Our case highlights the need to look for androgendependent hairs beyond the mons pubis, in the perianal area to consider the diagnosis of CAH, a potentially life-threatening condition, if untreated.