Classic Congenital Adrenal Hyperplasia Presenting as Primary Amenorrhea

A bstract Congenital adrenal hyperplasia (CAH) is a group of disorders of cortisol biosynthesis, most commonly due to 21-hydroxylase deficiency, which accounts for over 90% of cases. CAH is classified into classic and nonclassic forms: the classic type presents in infancy with salt-wasting crises or virilization of external genitalia in females, whereas the nonclassic type manifests later with hirsutism and/or menstrual irregularities. Delayed recognition of classic simple virilizing CAH beyond childhood is uncommon. We report the case of a young woman in her 20s with classic simple virilizing CAH who presented with primary amenorrhea, short stature, hirsutism, and clitoromegaly. Biochemistry showed markedly elevated 17-hydroxyprogesterone, and pelvic ultrasonography revealed a hypoplastic uterus with normal ovaries. Initiation of glucocorticoid therapy led to resumption of menstrual spotting and improvement in hirsutism and acne. This case highlights the consequences of delayed diagnosis, reinforces the need to include CAH in newborn screening programs, and emphasizes that CAH should be kept in the differential diagnosis of females presenting with amenorrhea and features of hyperandrogenism.