Inflammatory linear verrucous epidermal nevus in Adult
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.
D23.9 – Other benign neoplasm of skin, unspecified
399995006 – Inflammatory linear verrucous epidermal nevus
Differential Diagnosis & Pitfalls
- Linear psoriasis – Some authors have postulated a relationship between linear psoriasis and ILVEN, and the independent existence of the 2 conditions has been questioned. Histopathology of ILVEN and linear psoriasis greatly overlap.
- Linear porokeratosis also occurs more often in female patients and follows the lines of Blaschko but is more likely to occur in adulthood. Skin cancer can arise within linear porokeratosis. Histopathology of linear porokeratosis maintains characteristic coronoid lamellae.
- Lichen striatus – A self-limited, unilateral inflammatory dermatosis of erythematous, flat-topped papules with scale arranged in a linear band that progresses down an extremity. Histopathology reveals a lichenoid condition with interface reaction and a deeper periadnexal lymphocytic infiltrate.
- Papular epidermal nevus with "skyline" basal cell layer (PENS) is a rare entity in which affected children develop a few hyperkeratotic polygonal or rectangular papules in one or more body locations. PENS syndrome describes a subset of patients with PENS with associated neurological findings such as epilepsy or neurodevelopmental delay.
- CHILD nevus – A mosaic inflammatory / ichthyosiform disorder with X-linked dominance. A mosaic mutation in NSDHL has been shown to cause nevi near identical to ILVEN in dogs.