Target lesions are observed in case of
**Core Concept**
Target lesions are a specific type of skin rash characterized by a central area of clearing surrounded by concentric rings of erythema, often seen in systemic lupus erythematosus (SLE) and other autoimmune conditions. The pathogenesis of target lesions involves immune complex deposition and complement activation.
**Why the Correct Answer is Right**
The correct answer is related to the pathophysiology of autoimmune diseases, where the immune system produces autoantibodies that bind to the skin, leading to inflammation and the characteristic target lesion appearance. In SLE, the deposition of immune complexes in the skin involves the complement system, specifically the activation of C3 and the formation of the membrane attack complex (MAC). This process results in the characteristic target lesions seen in patients with SLE.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because while it may be a manifestation of an autoimmune disease, it is not the most specific or characteristic presentation of target lesions.
**Option B:** This option is incorrect because it refers to a different type of skin lesion altogether, and is not related to the pathophysiology of target lesions.
**Option C:** This option is incorrect because while it may be a manifestation of an autoimmune disease, it is not as specific or characteristic as target lesions.
**Clinical Pearl / High-Yield Fact**
Target lesions are a classic sign of SLE and should prompt a thorough evaluation for autoimmune disease, including serological testing for ANA and anti-dsDNA antibodies.
**Correct Answer:** C. Systemic lupus erythematosus.