Erythema nodosum is seen in all of the following except –
**Core Concept**
Erythema nodosum (EN) is a type of skin inflammation that involves the formation of nodular lesions, typically on the lower extremities. This condition is associated with various underlying causes, including infections, medications, and systemic diseases.
**Why the Correct Answer is Right**
Erythema nodosum is a form of panniculitis that primarily affects the subcutaneous fat. The lesions typically resolve within 2-6 weeks, but recurrence is common. The pathophysiology of EN involves an immune-mediated response, often triggered by an infectious agent or a medication. The exact mechanism is not fully understood, but it is believed to involve the activation of neutrophils and macrophages, leading to the release of pro-inflammatory cytokines and the formation of granulomas.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because sarcoidosis is actually a common cause of erythema nodosum. EN can occur in up to 25% of patients with sarcoidosis.
**Option B:** This option is incorrect because erythema nodosum is indeed associated with inflammatory bowel disease (IBD), particularly Crohn's disease and ulcerative colitis. EN is often a manifestation of the extraintestinal manifestations of IBD.
**Option C:** This option is incorrect because erythema nodosum can occur in association with various medications, including sulfonamides, penicillins, and oral contraceptives.
**Clinical Pearl / High-Yield Fact**
A key clinical feature of erythema nodosum is the presence of tender, erythematous nodules on the lower extremities, often accompanied by fever, malaise, and arthralgias. EN can be a manifestation of an underlying systemic disease, and a thorough evaluation is necessary to identify the underlying cause.
**Correct Answer: D.**