Isolated Premature Menarche in a 17-Month-Old: A Case Report

BACKGROUND Vaginal bleeding in prepubertal girls is an uncommon finding and should always prompt thorough evaluation. Puberty is a complex physiological process resulting from maturation of the hypothalamic-pituitary-gonadal axis. Precocious puberty is defined as the early onset of secondary sexual characteristics before the age of 8 years in girls. The incidence ranges from 1 in 5000 to 1 in 10 000 girls worldwide. In contrast, isolated premature menarche is a rare and benign condition characterized by vaginal bleeding without other signs of pubertal activation and remains a diagnosis of exclusion. CASE REPORT We report a 17-month-old female infant who presented with recurrent vaginal bleeding every month over the 3 months prior to admission. Physical examination showed normal external genitalia, with no signs of inflammation, trauma, foreign body, or sexual abuse. There were no secondary sexual characteristics, and growth parameters were appropriate for age. Laboratory examination revealed prepubertal basal gonadotropin levels, normal hormonal levels, normal thyroid function tests, and bone age consistent with chronological age. Platelet function testing showed hyperaggregation, considered a transient and incidental finding. Pelvic ultrasonography demonstrated the size of the uterus was consistent with the age of puberty. After exclusion of local, endocrine, and systemic causes, a diagnosis of isolated premature menarche was established. CONCLUSIONS Menstrual-like vaginal bleeding in prepubertal girls requires systematic and comprehensive examination to differentiate isolated premature menarche from other diseases. Recognition of this benign entity is important to avoid unnecessary interventions and ascertain appropriate follow-up.