A 19-year-old patient complains of primary amenorrhea. She had well developed breast and pubic hair but on examination there was absence of uterus and vagina. Likely diagnosis is :
**Core Concept**
The patient's primary amenorrhea, normal breast and pubic hair development, but absence of uterus and vagina suggests a disorder of sex development (DSD) with androgen insensitivity. This condition is characterized by the presence of a 46,XY karyotype, normal testes, and resistance to androgens due to mutations in the androgen receptor (AR) gene.
**Why the Correct Answer is Right**
The patient's clinical presentation is consistent with complete androgen insensitivity syndrome (CAIS), where the testes produce normal amounts of testosterone, but the body is unable to respond due to the mutated AR gene. This leads to the development of female secondary sexual characteristics, such as breast and pubic hair, but the absence of a uterus and vagina due to the failure of Müllerian duct regression. The presence of testes, but not the development of a penis, is also a characteristic feature of CAIS.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the patient's presentation. Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome is a condition characterized by the absence of the vagina and uterus in individuals with a normal karyotype and normal ovarian function.
**Option B:** This option is not consistent with the patient's clinical presentation. Turner syndrome is a chromosomal disorder characterized by the absence of one X chromosome (45,X) and is not associated with androgen insensitivity.
**Option C:** This option is not relevant to the patient's presentation. Congenital adrenal hyperplasia (CAH) is a group of disorders that result from defects in the enzymes involved in cortisol production, leading to an overproduction of androgens. While CAH can cause virilization in females, it is not associated with the absence of a uterus and vagina.
**Option D:** This option is not correct. Swyer syndrome is a condition characterized by a 46,XY karyotype, normal testes, and the development of a blind-ending vagina and rudimentary uterus. While Swyer syndrome shares some features with CAIS, it is not the most likely diagnosis in this case.
**Clinical Pearl / High-Yield Fact**
The presence of a 46,XY karyotype and normal testes in a patient with primary amenorrhea and absence of a uterus and vagina should raise suspicion for androgen insensitivity, which can be diagnosed with molecular genetic testing for the AR gene.
**Correct Answer:** C.