Differential Diagnosis for Amenorrhea in a 16-year-old Girl
- Single most likely diagnosis:
- Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome: This condition is characterized by the congenital absence of the uterus and vagina in individuals with a 46,XX karyotype. The presence of normal ovarian function (indicated by Tanner stage 4 breast development and pubic and axillary hair) and the absence of a uterus on pelvic ultrasonography strongly support this diagnosis.
- Other Likely diagnoses:
- Androgen Insensitivity Syndrome (AIS): Although less likely given the presence of axillary hair, AIS could be considered if there were any signs of androgen resistance. However, the normal development of pubic and axillary hair makes this less probable.
- Gonadal Dysgenesis: This condition involves abnormal development of the gonads and could lead to amenorrhea. However, the presence of normal-sized ovaries on ultrasonography makes this less likely.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed):
- Adrenal or Ovarian Tumors: Although rare, tumors could cause hormonal imbalances leading to amenorrhea. It's crucial to rule out any malignancy, especially given the patient's symptoms and physical findings.
- Pituitary or Hypothalamic Tumors: These could affect the hypothalamic-pituitary-gonadal axis, leading to amenorrhea. Given the patient's otherwise normal examination and lack of other symptoms, this is less likely but should not be missed due to the potential severity.
- Rare diagnoses:
- Congenital Adrenal Hyperplasia (CAH): This is a group of inherited disorders that affect the adrenal glands, leading to hormone imbalances. While CAH could cause amenorrhea, the patient's presentation and normal physical examination make this less likely.
- Turner Syndrome: Characterized by a 45,X karyotype, this condition often presents with short stature and gonadal dysgenesis. The patient's height at the 80th percentile and normal ovarian size make this diagnosis unlikely.
- Swyer Syndrome: This rare condition involves a 46,XY karyotype with gonadal dysgenesis, often presenting with amenorrhea. The presence of normal-sized ovaries and the lack of other indicative features make this diagnosis less probable.