Differential Diagnosis for Primary Amenorrhea
The patient's presentation of primary amenorrhea, normal breast development, scant axillary and pubic hair, and the absence of the uterus, cervix, and ovaries on bimanual examination guide the differential diagnosis.
Single Most Likely Diagnosis
- Mayer-Rokitansky-Küster-Hauser (MRKH) Syndrome: This condition is characterized by the congenital absence of the vagina, cervix, and uterus in individuals with a 46,XX karyotype. The presence of normal breast development (Tanner stage 5) and the absence of the uterus, cervix, and ovaries, along with a blind vaginal pouch, strongly suggest MRKH syndrome. The patient's normal secondary sexual characteristics and the absence of any developmental delay or other systemic anomalies further support this diagnosis.
Other Likely Diagnoses
- Androgen Insensitivity Syndrome (AIS): Although less likely given the scant axillary and pubic hair, AIS should be considered. Individuals with complete AIS have a 46,XY karyotype, normal breast development, and typically, little to no axillary or pubic hair due to the inability of their bodies to respond to androgens. However, the presence of a blind vaginal pouch and the absence of testes in the labia or inguinal canals make MRKH more likely.
- Gonadal Dysgenesis: This includes conditions like Turner syndrome (45,X) and other sex chromosome abnormalities. However, the patient's normal height, absence of developmental delay, and normal breast development make these conditions less likely.
Do Not Miss Diagnoses
- Ovotesticular Disorder of Sex Development (OT-DSD): Although rare, this condition involves the presence of both ovarian and testicular tissue, which could lead to varying degrees of virilization and internal genitalia abnormalities. It's crucial to consider due to the potential for malignancy in undescended gonads.
- Adrenal Hyperplasia: Congenital adrenal hyperplasia can cause virilization and amenorrhea, but the absence of acne, excessive hair growth, and the specific findings on physical examination make this less likely.
Rare Diagnoses
- Swyer Syndrome: Characterized by a 46,XY karyotype, normal female external genitalia, and streak gonads. Patients often present with primary amenorrhea and normal secondary sexual characteristics but have an increased risk of gonadal tumors.
- Other Rare Genetic Syndromes: Such as Fraser syndrome, which can involve genital anomalies among other systemic findings. These are less likely given the patient's otherwise normal development and physical examination findings.