Abstract
Answer C. Tanner stage 3
The boy's presentation with enlargement of testes and scrotum, lengthening of the penis, and sparse, darker pubic hair at the base of the penis is most consistent with Tanner stage 3. This stage typically occurs between 9 and 14 years of age, which aligns with the patient's age of 13. The staging suggests:
Tanner stage 1 (pre-pubertal): No pubic hair, genitalia same as early childhood. This doesn't match the description. Tanner stage 2: Enlargement of testes and scrotum, sparse pubic hair at base of penis. While some of these features are present, the lengthening of the penis indicates a more advanced stage. Tanner stage 3: Penis begins to lengthen, further enlargement of testes and scrotum, pubic hair becomes coarser and darker. This matches the description given in the scenario. Tanner stage 4: Penis continues to grow in length and breadth, pubic hair takes on an adult pattern but doesn't spread to thighs. The description doesn't mention adult-like pubic hair pattern, so this stage is too advanced. Tanner stage 5: Genitalia reach adult size and shape, pubic hair spreads to medial thighs. This is clearly more advanced than the described presentation.
InnovAiT article: Disorders of puberty. DOI: 10.1177/17557380241298174.