lichen simplex chronicus

Definition : Lichen simplex chronicus has marked hyperkeratosis, focal parakeratosis, a prominent granular cell layer, elongated rete and perivascular and interstitial inflammation.

Lichen simplex chronicus (LSC) is a skin disorder characterized by lichenification of the skin as a result of primary excessive scratching.

LSC (circumscribed neurodermatitis) is characterized by a central lichenificated plaque thickened and often hyperpigmented, usually surrounded by lichenoid papules and, along the borders with surrounding normal skin, by an indefinite zone of slight thickening.

The most common sites are the neck (sides), ankles, scalp, vulva, pubis, scrotum, and extensor forearms. The peak of incidence is between 35 and 50 years of age, and women are more affected than men (F:M = 2:1).

Microscopy

 Early histological changes: spongiotic dermatitis (Semin Diagn Pathol 2017;34:220)
 Evolves to demonstrate (Semin Diagn Pathol 2017;34:220)

• Prominent acanthosis with curvilinear, blunt rete ridges
• Compact orthokeratosis with focal parakeratosis and hypergranulosis
• Papillary dermal fibrosis
• Variable intraepidermal and superficial perivascular dermal chronic inflammatory infiltrate
• Rare mast cells and eosinophils

The histopathological features in lichen simplex are epidermal hyperplasia, orthokeratosis, and hypergranulosis with a regular elongation of the rete ridges.

There is a perivascular infiltrate of lymphocytes and occasionally of macrophages. The macrophages are not clearly dendritic as in PN and much less numerous.

Moreover, in LSC there is no neural hyperplasia and abundancy of NGF and lack of positive immunostaining for NGF receptor mediators of pruritus as in PN.

See also

 inflammatory cutaneous anomalies

• nodular prurigo

Open references

 https://onlinelibrary.wiley.com/doi/full/10.1111/j.1529-8019.2008.00168.x