Differential Diagnosis for Non-Palpable Testes in a 15-Month-Old

Single Most Likely Diagnosis

• Cryptorchidism: This is the most common diagnosis for non-palpable testes in infants and young children. Cryptorchidism, or undescended testes, occurs when one or both testicles have not moved down into the scrotum. It is a common condition in premature infants but can also occur in full-term babies. The likelihood of spontaneous descent decreases with age, making intervention more likely to be considered around this age.

Other Likely Diagnoses

• Retractile Testes: These are testes that can move up and down from the scrotum into the groin and back. They might not be palpable at all times, especially in cold environments or during examination if the child is frightened or upset.
• Ectopic Testes: These are testes that have migrated to an abnormal location outside the normal path of descent, such as the superficial inguinal pouch or the perineum. They are less common than undescended testes but can be a cause of non-palpable testes.

Do Not Miss Diagnoses

• Testicular Torsion: Although less common in this age group, testicular torsion is a surgical emergency that requires immediate attention. It can cause severe pain and might lead to the testicle not being palpable due to swelling or the testicle being in an abnormal position.
• Testicular Regression Syndrome (Vanishing Testis): This condition occurs when a testis is present during fetal development but atrophies and disappears before birth. It's crucial to differentiate this from other causes of non-palpable testes, as it has implications for fertility and potential testicular cancer risk.

Rare Diagnoses

• Androgen Insensitivity Syndrome (AIS): A condition where an individual is genetically male (XY chromosomes) but has resistance to male hormones (androgens). This can lead to the development of female external genitalia despite the presence of testes, which might not be palpable.
• Gonadal Dysgenesis: A condition where the gonads (testes or ovaries) do not develop properly. In cases of mixed gonadal dysgenesis, there might be abnormal or non-palpable gonads.
• Other Genetic Syndromes: Certain genetic syndromes can be associated with undescended testes or abnormalities of testicular development, such as Klinefelter syndrome, though these are less common causes of non-palpable testes in infancy.