MON-241 - A Diagnostic Trap: Ovarian Hyperstimulation Syndrome Mimicking Central Precocious Puberty in A Term Infant

Introduction: Preterm ovarian hyperstimulation syndrome (POHS) represents an important alternative diagnosis that can present early estrogenization in infancy. Classically described in premature infants (24 - 31 weeks of gestation) at 35 to 39 weeks of periconceptional age. It’s characterized by thelarche, vaginal bleeding, oedema of clitoris and labia, increased estrogen (E) levels, with pubertal-level gonadotropins and large ovarian cysts. Most reported cases of POHS resolve spontaneously by 10 to 14 months of age without intervention, as long as there is no risk of cyst torsion. To our knowledge, POHS-like condition has not been reported in full-term infants.

Case: We report a full-term (38 weeks) female infant with severe neurologic comorbidities (developmental delay, heterozygous EEF1A2 variant consistent with epileptic encephalopathy), pulmonary hypertension, chronic lung disease, and gastrostomy dependence. At 4 months, she presented breast budding with galactorrhea, vaginal bleeding and pubic hair, negative for café au lait spots. Growth pattern without accelerated linear growth. Biochemically had elevated E 1,111 pg/mL (Normal Range in Mini-Puberty: 20-50 pg/mL) detectable pubertal LH and FSH (4.8 and 2.9 mIU/ml respectively), elevated prolactin (170 – Normal ranges: 20 -40 ng/ml). Adrenal profile and ACTH stimulation test were normal, excluding adrenal insufficiency. US showed a pubertal-sized uterus and left enlarged ovary, including a 1.8 cm cyst. Pituitary MRI was normal. For the next 3 months, the ovaries showed multiple waxing and waning pattern cysts with a maximum size of 4 cm, without torsion. Daughter cysts were also noted. Pubertal gonadotrophins were detected during this period along with extremely elevated E levels. At 9 months, mild central hypothyroidism was diagnosed and treated.

Results: After 12 months resolution of ongoing pubertal development, E, gonadotropins, and ovarian volumes to pre-pubertal levels with residual uterine enlargement was noted. The spontaneous improvement of hyperestrogenism and the presence of large ovarian cysts with daughter cysts support a diagnosis similar to POHS. In contrast, central precocious puberty (CPP) reflects premature activation of the hypothalamic–pituitary–gonadal (HPG) axis and is characterized by progressive secondary sexual characteristics persistently pubertal gonadotropin secretion, E, advancing bone age, that may not spontaneously regress and usually requires medical suppression. Alternatively self-limiting physiologic mini puberty occurs during transient activation of HPG axis with modest E levels and ovarian cyst < 9 mm, occurs during first months after birth, lasting up to 12–24 months in girls. Up to date, there is no known link between EEF1A2 and ovarian hyperstimulation, presentation was not explained by other causes such as hypothyroidism, adrenal or neoplastic.

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