A 66-year-old Vietnam-born Chinese man was admitted to our department because of progressive abdominal swelling and bilateral ankle oedema for 1 year. On physical examination, he was noted to have a short stature with body height of 1.37 m. He had a normal complexion and no other dysmorphic features. His blood pressure was 99/55 mm Hg but with no postural drop. Abdominal examination revealed a distended abdomen without organomegaly or shifting dullness. Examination of his external genitalia revealed a micropenis with perineoscrotal hypospadias (Prader stage IV); no testes could be detected in/along both the scrotum and inguinal canals. However, he had male pattern of escutcheon, a beard, and no gynaecomastia. On further questioning, he reluctantly disclosed a history of urinary leakage since childhood and arrest of growth after puberty at the age of 10 years. Computed tomography of the abdomen revealed a 13.6 x 26.5 x 23.7 cm non-enhancing septated cystic mass arising from the retrovesical region.Initial investigations revealed normal serum electrolytes and acid-base status. His renal function was impaired (serum creatinine of 172; reference range [RR], 62-126 μmol/L), and he had hypoalbuminaemia (serum albumin of 24; RR, 32-46 g/L). Baseline serum sex hormone profiles were as follows: testosterone at 9.2 (RR for male, 9.0-34.7) nmol/L, oestradiol at 176 (RR for male, 26-156) pmol/L, progesterone at 22.8 (RR for male, 0.7-4.3) nmol/L, luteinising hormone at 1.9 (RR, 1.7-8.6) IU/L, follicle-stimulating hormone at 3.0 (RR, 1.5-12.4) IU/L, androstenedione at 31.5 (RR, 0.8-3.1) nmol/L, and dehydroepiandrosterone sulfate at 11.6 (RR, 2.2-15.2) nmol/L. Tumour markers including beta-human chorionic gonadotropin, alpha-fetoprotein, carcinoembryonic antigen, and CA-125 were normal. A mosaic Turner karyotype with 10% monosomy X, 4% trisomy X, and 86% normal female karyotype was detected. The short synacthen test with 250 μg tetracosactrin was performed to unravel the possibility of congenital adrenal hyperplasia (CAH) with the following results: baseline adrenocorticotropic hormone (ACTH) at 50.2 (RR, <10.1) pmol/L; baseline and 60-minute post-stimulation serum cortisol at 224 and at 260 nmol/L, respectively (reference level, >550 nmol/L post-stimulation); and baseline and 60-minute post-stimulation 17-hydroxyprogesterone (17-OHP) at 70 and 554 nmol/L, respectively (reference level of classical CAH, >300 nmol/L). Urinary steroid profiling (USP) by gas chromatography-mass spectrometry (GC-MS) showed grossly elevated metabolites of 17-OHP (Fig 1), including pregnanetriol, 17-hydroxypregnenolone and 11-oxo-pregnanetriol, compatible with 21-hydroxylase deficiency (21-OHD). Mutational analysis of the CYP21A2 gene by multiplex ligation-dependent probe amplification and by polymerase chain reaction (PCR) followed by direct DNA sequencing showed deletion/ conversion of the promoter to exon 4 in one allele and a hemizygous p.Ile172Asn mutation in the other allele. Using PCR no SRY gene could be amplified in the peripheral leukocyt...