Differential Diagnosis

The symptoms described, including small penis, less pubic hair, feminine voice, less height, webbed neck, and polydactyly, suggest a range of potential diagnoses. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis
  • Klinefelter Syndrome: Characterized by an extra X chromosome in males (47,XXY), leading to features such as small testes, less body hair, a higher-pitched voice, and sometimes a webbed neck. However, polydactyly is not a typical feature, making this diagnosis less certain based on the provided symptoms alone.
• Other Likely Diagnoses
  • Turner Syndrome (Mosaicism): Although typically associated with females (45,X), mosaicism can lead to a mix of sex chromosomes, potentially resulting in males with features like short stature, webbed neck, and sometimes genital abnormalities. However, the presence of a small penis and polydactyly might not fully align with typical Turner Syndrome presentations.
  • Androgen Insensitivity Syndrome (AIS): Partial AIS could result in a phenotype with some feminization (e.g., higher-pitched voice, less body hair) due to partial resistance to androgens, but the presence of polydactyly and a webbed neck is not characteristic.
• Do Not Miss Diagnoses
  • Noonan Syndrome: This genetic disorder can present with short stature, webbed neck, and heart defects. While it doesn't typically cause genital abnormalities like a small penis, its presence on the differential is crucial due to its potential for serious cardiac complications.
  • Congenital Adrenal Hyperplasia (CAH): Certain forms of CAH can lead to undervirilization in males, but the combination with polydactyly and a webbed neck would be unusual.
• Rare Diagnoses
  • Smith-Lemli-Opitz Syndrome: A rare genetic disorder that can result in undervirilization, polydactyly, and other congenital anomalies, but it's less commonly associated with the specific combination of symptoms described.
  • Robinow Syndrome: Characterized by short stature, genital abnormalities, and sometimes polydactyly, but it's a rare condition and might not fully account for all the symptoms mentioned, such as a feminine voice.

Each of these diagnoses has a unique set of characteristics, and the combination of symptoms provided suggests a complex clinical picture that may require further investigation, including genetic testing, to accurately diagnose.