Cutaneous sarcoidosis of the scalp unmasking systemic involvement: A case report.

Sarcoidosis is a multisystemic granulomatous disease of unknown cause that affects any organ, especially the lungs, eyes, lymph nodes and skin. Skin sarcoidosis occurs in about one-fourth of patients with systemic disease and may also arise in isolation. Skin lesions are divided into two groups, as follows: specific skin lesions where histologic examination shows the typical sarcoid granulomas and non-specific skin lesions. Specific lesions are lupus pernio, infiltrated plaques, maculopapular eruptions, subcutaneous nodules and scars. The most significant non-specific skin lesion seen in sarcoidosis is erythema nodosum. Cutaneous sarcoidosis is known as the 'great imitator' in dermatology, because it can mimic a vast variety of cutaneous lesions. The diagnosis of sarcoidosis is made by exclusion and is supported by the recognition of specific clinical features, the detection of classic histopathologic findings and the exclusion of other granulomatous diseases. We present a case report concerning a single, solitary and asymptomatic lesion on the scalp.