Partial androgen insensitivity syndrome with Müllerian duct derivatives complicated by a testicular seminoma

Androgen insensitivity syndrome (AIS) is a condition that affects sexual development before birth and during puberty and is one of the more common disorders affecting masculinisation of the male genitalia. This rare syndrome (affecting 2–5 per 100,000 genetic males) is classified as complete (CAIS), partial (PAIS) or mild depending upon the extent of residual functional androgen receptors (AR) which in turn influence the phenotype. Mutations of AR have been reported in approximately 95% of persons with CAIS and in 10% with PAIS.1

Genital ambiguity is variable in PAIS with a frequent phenotype of micropenis, posterior hypospadias and cryptorchidism. PAIS has a higher risk of associated malignancy than in CAIS.2 Current evidence recommends the retention of cryptorchid testes through puberty for hormone production benefits, including bone and secondary sexual development.3

Müllerian duct derivatives (such as fallopian tubes, uterus, cervix and upper vagina) are usually absent in patients with AIS but the occasional presence in some raise the possibility of either defective production or response to Müllerian inhibitory factor (MIF).