American Board of Internal Medicine (ABIM) Certification Practice Exam

What condition is characterized by reddish, tender nodules on the lower extremities?

1. Erythema nodosum

2. Pyoderma gangrenosum

3. Achalasia

4. Insulinoma

The correct answer is: Erythema nodosum

Erythema nodosum is characterized by the appearance of reddish, tender nodules primarily found on the lower extremities. These painful, raised lesions are often a sign of an underlying inflammatory process and can be associated with various conditions, including infections, medications, and systemic diseases. The nodules develop in the subcutaneous fat layer and can vary in size, usually presenting as warm and tender to the touch. The condition is considered a hypersensitivity reaction or a type of panniculitis, where inflammation occurs in the fat tissue. It is often linked to infections (such as streptococcal infections), certain medications, autoimmune diseases, or even pregnancy. The other conditions in the options provided do not match this specific presentation. For instance, pyoderma gangrenosum typically manifests as painful ulcers rather than nodules and is associated with inflammatory conditions. Achalasia primarily affects the esophagus and has no connection to skin lesions. Insulinoma, a type of pancreatic tumor, typically presents with symptoms of hypoglycemia rather than a dermatological condition. Hence, the distinctive characteristics of erythema nodosum clearly identify it as the correct answer for this question.