A patient with the typical cutaneous lesions which are slightly elevated red or purple macules that are often covered by gray or yellow adherent scales. Forceful removal of the scale reveals numerous ‘carpet tack’ extensions, reveals the lesion as:
**Core Concept**
The patient's skin lesions are described as having a characteristic appearance with elevated red or purple macules covered by adherent scales, and upon forceful removal of the scale, 'carpet tack' extensions are seen. This presentation is suggestive of a specific dermatological condition characterized by abnormal keratinization and parakeratosis.
**Why the Correct Answer is Right**
The 'carpet tack' appearance is a hallmark of psoriasis, a chronic inflammatory skin disease. The scales in psoriasis are attached to the underlying skin by short, finger-like projections called 'carpet tack' or 'squamary projections.' These projections are due to the abnormal proliferation of keratinocytes and the failure of normal desquamation. The 'carpet tack' appearance is a key diagnostic feature of psoriasis, especially in the context of the described skin lesions.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not accurately describe the 'carpet tack' appearance associated with psoriasis. The scales in psoriasis are not typically described as being 'loosely adherent.'
**Option B:** This option is incorrect as it does not accurately describe the 'carpet tack' appearance associated with psoriasis. The scales in psoriasis are not typically described as being 'diffusely crusted.'
**Option C:** This option is incorrect as it does not accurately describe the 'carpet tack' appearance associated with psoriasis. The scales in seborrheic dermatitis are typically greasier and less adherent than those seen in psoriasis.
**Clinical Pearl / High-Yield Fact**
A key diagnostic feature of psoriasis is the presence of 'carpet tack' or 'squamary projections' seen upon forceful removal of the scale. This characteristic appearance is a useful clue in differentiating psoriasis from other dermatological conditions.
**Correct Answer:** A. Psoriasis.