Endocrine Abstracts

Introduction: 46 XY Disorders of Sex Development (46, XY DSD) is defined by the presence of female or incompletely virilized external genitalia in a 46, XY individual. 17β-hydroxysteroid dehydrogenase 3 (17βHSD3) deficiency is one of the causes for testosterone biosynthetic defects. It leads to defective conversion of androstenedione to testosterone. 17βHSD3 deficiency can present with female phenotype with inguinal hernias at birth, clitoromegaly during infancy or virilization of a female child during puberty. It can also present as gynaecomastia in males. We report a case of 17βHSD3 deficiency which presented with gynaecomastia.

Case report: 10-year-old child presented with enlargement of both breasts for 7 months, not associated with pain, galactorrhoea. At birth child was identified as female, however at 5 months of age, karyotype was done in view of enlarged phallic structure. It revealed 46, XY and child’s gender was re-assigned as male. At 5 months, Testosterone was 1.5ng/ml, & Dihydrotestosterone (DHT) 77pg/ml. Post stimulation with HCG, Testosterone was 2.6ng/ml, DHT 128pg/ml. This suggested testosterone biosynthetic defect & androstenedione was not measured. Child underwent orchidopexy and staged penile reconstruction. Left testis was atrophic and left in situ. Currently on examination, child’s growth was normal with height and weight being above 90th percentile. Androstenedione level was 2.76ng/ml. Testosterone to androstenedione ratio was 0.55(low) which was suggestive of 17βHSD3 deficiency. Genetic analysis confirmed the diagnosis.

Conclusion: 17βHSD3 deficiency is one of the differential diagnosis of ambiguous genitalia in a 46 XY individual. It may be confused with 5α-reductase deficiency and complete androgen insensitivity syndrome. The case highlights the importance of androstenedione and need to suspect when gynaecomastia is present at pubertal age. Timely evaluation and diagnosis helps in preventing complications like testicular malignancy.