Inflammatory linear verrucous epidermal nevus (ILVEN) is a blaschkoid dermatosis that presents with erythematous, hyperkeratotic plaques following Blaschko lines. It occurs most often on the buttocks, perineal area, and lower extremities, particularly in girls, and often on the left side of the body.

ILVEN typically becomes clinically apparent in early childhood; however, adult-onset variants have been reported. While typically sporadic in occurrence, familial forms have been described. Pruritus is common with ILVEN, and the condition is typically only partially responsive to topical management.

ILVEN was historically classified as a type of epidermal nevus. However, current thinking by many experts is that, rather than being a true epidermal nevus, ILVEN may represent a mosaic inflammatory disorder akin to linear psoriasis and linear lichen planus or a mosaic ichthyosiform disorder. This is theorized because ILVEN has shown response to therapies for psoriasis, such as topical calcipotriene, topical corticosteroids, 308 nm excimer laser, and biologics such as etanercept. ILVEN has been reported in patients who go on to develop widespread psoriasis. Additionally, further investigation has shown aberrant interleukin (IL)-36R / IL-17R pathways in ILVEN, similar to psoriasis and psoriasiform ichthyoses. Further, localized upregulation of IL-1, IL-6, tumor necrosis factor alpha (TNF-α), and intercellular adhesion molecule 1 (ICAM-1) may play a role in its development and perpetuation. About 10% of patients were genetic mosaics for CARD14 in DNA from blood and affected skin.

Some cases of ILVEN have been associated with autoimmune thyroiditis. A rare complication of ILVEN is development of superimposed verruciform xanthomas in adulthood.