Lichen spinulosus

 

Salient features

 

·       Clusters of multiple follicular papules, each with a keratotic spine

 

·       Texture likened to that of a nutmeg grater

 

·       Usually asymptomatic, arises suddenly, and enlarges over a week

 

·       Appears most often in children and adolescents; favors the neck, extensor arms, abdomen, and buttocks

 

·       Can persist indefinitely

 

Introduction

Lichen spinulosus (LS) is a rare idiopathic condition, characterized byacute eruption of skin-colored grouped hyperkeratotic follicular papules arranged into large plaques.

 

Epidemiology

Age

 

LS is a disease of children and young adults with an average age of onset is 16 years.

 

Sex

 

Equal distribution of LS in males and females.

 

 

Pathogenesis

 

Although several factors, such as atopy, infections and heredity, have been proposed as playing a role in lichen spinulosus, the exact etiology is unknown and most patients do not have associated systemic abnormalities. Some authors feel that LS is a variant of KP: the conditions share the same features on histology.

 

Pathology

 

Histologically, lichen spinulosus most resembles keratosis pilaris. Hair follicles are dilated by a thick keratinous plug, and surrounded by a chronic inflammatory infiltrate.

 

 

Clinical features

 

The skin lesion appears suddenly and consists of multiple, skin-colored, keratotic follicular papules, each of which has a pointed keratotic spine. Papules coalesce into plaques. Plaques are coarse to touch and the texture is likened to that of a nutmeg grater and typically measure 2–5 cm in diameter and are symmetrically distributed on the extensor surfaces of the limbs such as elbows and knees, neck, shoulders, as well as the abdomen, buttocks and popliteal fossae. The face, hands and feet are usually spared. Lesions often arise suddenly in crops, enlarge over a week, and then remain stationary. Idiopathic lichen spinulosus usually appears during childhood and adolescence and is asymptomatic, although in some patients the lesions are pruritic and the patches may be surrounded by faint erythema.

 

Disease course and prognosis

 

LS is a chronic but purely cosmetic disease. LS can persist for many years, but in most patients, it resolves spontaneously within 1–2 years.

 

Treatment

 

Treatment of LS is aimed at improving the cosmetic appearance. The mainstays of treatment are topical retinoids and keratolytics. Topical therapies such as 12% lactic acid, 20%–40% urea, and 6% salicylic acid may improve the texture. There are anecdotal reports of successful treatment with tacalcitol cream or tretinoin gel. Glycolic acid and salicylic acid peels have also been reported to be beneficial.