Keratosis lichenoides chronica (KLC), also known as Nekam disease, is a very rare chronic condition mostly seen in adults. It presents with erythematous, violaceous, or brown-purple, scaly lichenoid papules on the arms, legs, and lower trunk that form linear and/or reticulated plaques, usually symmetrically distributed, and a facial eruption that resembles seborrheic dermatitis or rosacea. It is usually asymptomatic, but pruritus may be an accompanying symptom.

The disease affects both sexes about equally. A majority of the patients in the literature are of Northern European descent, although patients of other ethnicities have also been reported. The pathogenesis of KLC has not yet been fully elucidated; however, a gain-of-function mutation in the NLRP1 gene has been identified in a family with KLC. Activation of NLRP1 leads to downstream release of proinflammatory mediators such as caspase-1 and subsequent activation of IL-1β and IL-18.

The mean time to diagnosis of KLC is 9 years given its rarity and similarities to other keratotic skin diseases. While it is a progressive condition, improvement has been reported with aging or in the summer.