Large bilateral painless effusions of the knees occurring in late congenital syphilis in patients between ages 8 to 18 are designated as
**Core Concept**
The question is testing the association between congenital syphilis and a specific clinical manifestation, namely large bilateral painless effusions of the knees. This condition is a classic example of a "late manifestation" of congenital syphilis, which can occur years after birth.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of congenital syphilis, which involves the transmission of Treponema pallidum from mother to fetus during pregnancy. The infection can cause a range of systemic manifestations, including skeletal and joint abnormalities. In late congenital syphilis, the infection can lead to the formation of large bilateral painless effusions of the knees, known as "clutton's joints." This occurs due to the involvement of the synovial membranes, which become inflamed and produce excess synovial fluid, leading to joint effusion.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it is not a recognized term associated with congenital syphilis.
* **Option B:** This option is incorrect because it is not a specific clinical manifestation of congenital syphilis.
* **Option C:** This option is incorrect because it is not a recognized term associated with congenital syphilis.
**Clinical Pearl / High-Yield Fact**
It is essential to remember that late congenital syphilis can manifest in various ways, including skeletal and joint abnormalities, such as Clutton's joints. These manifestations can occur years after birth, and a high index of suspicion is required for diagnosis.
**Correct Answer: C. Clutton's joints.**