Differential Diagnosis for Ambiguous Genitalia in a 2-Day-Old Infant
The patient's presentation of ambiguous genitalia, severe curvature of an underdeveloped phallus, and laboratory results guide the differential diagnosis.
Single Most Likely Diagnosis
- C. Congenital Adrenal Hyperplasia (CAH): This condition is the most likely diagnosis due to the presence of ambiguous genitalia in a 46,XX infant, indicating excessive androgen exposure during fetal development. CAH, particularly the 21-hydroxylase deficiency form, is a common cause of virilization in genetically female infants.
Other Likely Diagnoses
- D. Placental Aromatase Deficiency: Although less common, this condition can lead to maternal and fetal virilization due to the placenta's inability to convert androgens to estrogens. However, the mother's lack of symptoms (acne, hirsutism) makes this less likely.
- A. 5-Alpha Reductase Deficiency: Typically presents with a 46,XY karyotype and underdeveloped male genitalia, which does not match this patient's 46,XX karyotype.
Do Not Miss Diagnoses
- E. Sertoli-Leydig Cell Tumor: Although rare, this tumor can produce androgens, leading to virilization. It's crucial to consider due to its potential impact on fertility and malignancy risk, but the absence of a palpable mass makes it less likely.
- B. Androgen Insensitivity Syndrome: Usually presents with a 46,XY karyotype and female or partially female external genitalia due to resistance to androgen action. The high testosterone level in this case does not support this diagnosis as the primary issue.
Rare Diagnoses
- Other rare genetic disorders affecting sexual development, such as Denys-Drash Syndrome or Fraser Syndrome, could be considered but are less likely given the information provided and the specific laboratory findings.
- Maternal Exposure to Exogenous Androgens: Could potentially cause virilization of a female fetus, but the mother's reported medication (prenatal vitamins only) and lack of symptoms make this unlikely.