Endocrine Abstracts

Background: Turner syndrome (TS) is classically associated with gonadal dysgenesis, hypergonadotropic hypogonadism, and a hypoplastic uterus. Complete Müllerian agenesis is not a recognised feature of TS. In hypoestrogenic states, the uterus may appear absent on early imaging, posing diagnostic challenges and psychosocial distress for affected individuals.

Case Presentation: A 23-year-old woman with mosaic TS (45,X[5]/46,XX[25]) presented in 2019 with primary amenorrhea, minimal breast development (Tanner stage 2), and sparse pubic hair. Pelvic ultrasound and MRI suggested an absent uterus, cervix, and ovaries. Biochemistry confirmed hypergonadotropic hypogonadism with female-range testosterone, which is against androgen insensitivity syndrome. Bone age was delayed (13 years at chronological age 18). She commenced pubertal induction with estradiol patches, gradually titrated over three years, with the addition of cyclical progesterone. Early continuous progesterone use was complicated by low mood, necessitating regimen modification. She was also commenced on vitamin D and citalopram.

Results: She tolerated hormone therapy well, achieving Tanner progression, regular withdrawal bleeds, and improved psychosocial adjustment. Multidisciplinary monitoring included cardiac MRI/echo (normal thoracic aorta, Tri leaflet aortic valve), audiology (discharged with periodic GP review), and bone health surveillance. Repeat pelvic MRI in July 2025 demonstrated interval development of uterus and cervix (7 × 3 cm, endometrium 10 mm), with small adnexal tissues. This finding strongly suggested that the previously reported Müllerian agenesis was secondary to long-standing estrogen deficiency rather than true agenesis.

Conclusion: This case highlights that apparent “uterine agenesis” in mosaic Turner syndrome may in fact reflect profound hypoestrogenism, with potential for uterine development following prolonged hormone replacement. Clinicians should exercise caution in interpreting an absent uterus on adolescent imaging in hypoestrogenic states and consider re-imaging after pubertal induction. Structured pubertal induction, combined with multidisciplinary monitoring of cardiac, bone, auditory, and psychosocial health, is essential in optimising outcomes for women with Turner mosaicism.