eMedicine Specialties > Dermatology > Reactive & Inflammatory Dermatoses

Lichen Spinulosus

Author: Stephen W White, MD, Clinical Assistant Professor, Department of Dermatology, George Washington University Hospital
Coauthor(s): Christopher R Gorman, MD, Resident Physician, Department of Dermatology, University of Virginia School of Medicine
Contributor Information and Disclosures

Updated: Dec 15, 2006

Introduction

Background

Lichen spinulosus (LS) is an uncommon dermatosis manifested by large patches of follicular papules topped by keratotic spines (see Media Files 1-2). In 1883, Crocker published a description of LS. Since then, few other similar reports were published until 1990, when Friedman presented data on 35 patients with LS. The etiology is unknown. Some minor progress has been made in therapy.

Pathophysiology

The classic lesion of LS is a keratotic plug located within the dilated follicular orifice. Histologically, an inflammatory lymphohistiocytic infiltrate occurs around the follicle and in the dermis. Hyperkeratosis, parakeratosis, and acanthosis are visible in the follicle. Differentiating LS from keratosis pilaris by microscopy may not be possible.

Frequency

United States

Apparently, LS is not a common disorder. This conclusion is based on the paucity of published reports regarding LS. In the past, LS was reported to be associated with the administration of arsphenamine, thallium, gold, and diphtheria toxin. More recently, authors have noted association with HIV and Crohn disease. These associations may reflect the interests of the authors.

International

LS has been reported worldwide. In 1990, Friedman described 35 patients with LS. He and his coworkers in the Philippines examined 7435 people attending a dermatology clinic. The incidence of LS was approximately 5 cases per 1000 population with skin disorders. This prevalence exceeds reports from various American surveys on cutaneous diseases in children and adolescents.

Mortality/Morbidity

LS affects only the skin and is not known to be associated with abnormalities of internal organ systems. Occasionally, a patient with LS complains of pruritus. Otherwise, the disorder mostly is of cosmetic significance. Misdiagnosis can result in inappropriate treatment.

Race

Worldwide distribution suggests no predilection of LS in any ethnic group.

Sex

Case reports suggest an equal distribution in males and females. Friedman's study in the Philippines included 14 males and 21 females.

Age

Reports indicate that LS is a disease that occurs during childhood to young adulthood. Peak incidence appears to occur during adolescence. The condition can persist for decades. In most patients, LS remits spontaneously within 1-2 years. Friedman calculated that in the Philippines, the average age at onset was 16.2 years ± 10.1 years.

Clinical

History

LS tends to have a sudden onset and is not accompanied by other signs or symptoms. The keratotic papules group into large plaques that can spread rapidly to affect large areas of skin.

Physical

• Patches and plaques of follicular papules have a diameter that ranges from 2-5 cm.
  • Patches are distributed symmetrically over the integument.
  • Patches affect the neck, buttocks, abdomen, trochanters, knees, and extensor surfaces of the arms.
• Individual papules are flat to conical.
  • Individual papules usually are small, approximately 1-3 mm in diameter.
  • Papules have a pointed or hairlike horny spine that extends approximately 1 mm around the tip of the follicle.
  • When a patch is rubbed gently with the fingers, it feels similar to a nutmeg grater.

Causes

The cause of LS is unknown. Infection has been postulated, but no data support this hypothesis. Other authors have suggested that LS is part of atopy, but no association of LS with atopy was found in the Philippines. A report notes a family with the condition in 4 generations, an observation that suggests a genetic predisposition.

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