Background
Lichen spinulosus is an uncommon dermatosis manifested by large patches of follicular papules topped by keratotic spines, as shown in the image below. In 1883, Crocker published a description of lichen spinulosus. Since then, few other similar reports were published until 1990, when Friedman presented data on 35 patients with lichen spinulosus.[1] The etiology is unknown. Some minor progress has been made in therapy for lichen spinulosus.
View Image | Lichen spinulosus on the abdomen. |
View Image | Close-up view. |
Pathophysiology
The classic lesion of lichen spinulosus 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 lichen spinulosus from keratosis pilaris by microscopy may not be possible.
In the past, lichen spinulosus was reported to be associated with the administration of arsphenamine, thallium, gold, and diphtheria toxin. More recently, authors have noted association with HIV disease[2] and Crohn disease.[3] These associations may reflect the interests of the authors. Kabashima et al reported lichen spinulosus in an alcoholic patient.[4]
Epidemiology
Frequency
Apparently, lichen spinulosus is not a common disorder. This conclusion is based on the paucity of published reports regarding lichen spinulosus. Lichen spinulosus has been reported worldwide. In 1990, Friedman described 35 patients with lichen spinulosus. He and his coworkers in the Philippines examined 7435 people attending a dermatology clinic.[1] The incidence of lichen spinulosus 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.
Race
Worldwide distribution suggests no predilection of lichen spinulosus in any ethnic group.
Sex
Case reports suggest an equal distribution of lichen spinulosus in males and females. Friedman's study in the Philippines included 14 males and 21 females.
Age
Reports indicate that lichen spinulosus is a disease that occurs during childhood to young adulthood. Peak incidence appears to occur during adolescence. Lichen spinulosus can persist for decades. In most patients, lichen spinulosus remits spontaneously within 1-2 years. Friedman calculated that in the Philippines, the average age at onset was 16.2 years ± 10.1 years.
Prognosis
Lichen spinulosus can be ameliorated using emollient keratolytics. Case reports suggest that cure is the result of spontaneous remission over time. Most cases appear to remit within 1-2 years; however, well-documented cases exist that have lasted for decades.
Lichen spinulosus affects only the skin and is not known to be associated with abnormalities of internal organ systems. Occasionally, a patient with lichen spinulosus reports pruritus. Otherwise, the disorder mostly is of cosmetic significance. Misdiagnosis can result in inappropriate treatment.
History
Lichen spinulosus 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 Examination
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 lichen spinulosus is unknown. Infection has been postulated, but no data support this hypothesis. Other authors have suggested that lichen spinulosus is part of atopy, but no association of lichen spinulosus with atopy was found in the Philippines. A report notes a family with lichen spinulosus in four generations, an observation that suggests a genetic predisposition.
Complications
Lichen spinulosus is confined to the skin and has no known associations with internal disorders or genetic syndromes.
Approach Considerations
Caccetta et al proposed an algorithm for a clinical approach to the diagnosis of digitate keratoses.[8]
Laboratory Studies
Diagnosis should be made on clinical grounds alone. At present, no laboratory tests are specific or diagnostic for lichen spinulosus.
Histologic Findings
Histologic findings of lichen spinulosus are similar to those observed in keratosis pilaris. In lichen spinulosus, dilated hair follicles are filled with a keratotic plug. An inflammatory lymphocytic infiltrate occurs around the follicle and in the dermis. Hyperkeratosis, parakeratosis, and acanthosis may be present in the follicle.
Medical Care
No cure exists for lichen spinulosus, but some medications ameliorate its clinical manifestations. Because of the horny plug, keratolytics have been used as a treatment. These include salicylic acid, lactic acid, and/or urea in various creams, ointments, gels, and lotions.[9] The literature does not support the use of topical steroids in lichen spinulosus. The combination of tretinoin gel at bedtime with hydroactive adhesives the following morning has been reported to be efficacious.[10] . The successful use of topical tacalcitol cream was reported in two children with an atypical presentation of submental lichen spinulosus.[11] Successful treatment with topical adapalene has been reported.[12]
Consultations
Consultation with an experienced dermatologist is indicated if any doubt exists concerning the diagnosis.
Medication Summary
The goal of treatment for lichen spinulosus is to improve the cosmetic disfigurement caused by the disorder.
Ammonium lactate (Lac-Hydrin, Geri-Hydrolac)
Clinical Context:
Ammonium lactate contains lactic acid, an alpha-hydroxy acid with keratolytic action, thus facilitating release of comedones. It is available in 12% and 5% strengths. The 12% form may cause irritation on the face. Ammonium lactate causes disadhesion of corneocytes. It is found in a variety of topical emollient lotions. It may be combined with 10-20% urea cream or be used with salicylic acid gel.
Salicylic acid topical (Salacyn, Salvax, Keralyt, Gordofilm, SalAc)
Clinical Context:
Salicylic acid topical is a beta-hydroxy acid reported to soften papules. By dissolving intercellular cement substance, it produces desquamation of the horny layer of skin, while not affecting the structure of viable epidermis. It comes as a cream, lotion, or gel.
Urea (Carmol, Atrac-Tain, Nutraplus, Uramaxin, Uramaxin, Gormel, Nutraplus, Rea-Lo)
Clinical Context:
Urea promotes hydration and removal of excess keratin. It softens hyperkeratotic areas by dissolving the intracellular matrix, which loosens the horny layer of the skin.
Class Summary
Topical lactic acid creams have provided the most successful therapy to date. Salicylic acid gel and urea containing lotions also have been reported to help soften the horny papules. Gentle abrasion with a pad, soft brush, or luffa pad can be tried to remove the horny spines.
Adapalene (Differin)
Clinical Context:
Adapalene inhibits microcomedo formation. It decreases cohesiveness of keratinocyesin sebaceous follicles, which allows for easy removal. It has anti-inflammatory properties. Adapalene is available as a cream, lotion, or gel.
Class Summary
These agents stimulate cellular retinoid receptors and help normalize keratinocyte differentiation and are comedolytic. In addition, they have anti-inflammatory properties. The third-generation retinoids include topical adapalene and tazarotene.
Author
Christopher R Gorman, MD, Dermatologist, McGuire VA Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Richard P Vinson, MD, Assistant Clinical Professor, Department of Dermatology, Texas Tech University Health Sciences Center, Paul L Foster School of Medicine; Consulting Staff, Mountain View Dermatology, PA
Disclosure: Nothing to disclose.
Rosalie Elenitsas, MD, Herman Beerman Professor of Dermatology, University of Pennsylvania School of Medicine; Director, Penn Cutaneous Pathology Services, Department of Dermatology, University of Pennsylvania Health System
Disclosure: Received royalty from Lippincott Williams Wilkins for textbook editor.
Chief Editor
William D James, MD, Paul R Gross Professor of Dermatology, Vice-Chairman, Residency Program Director, Department of Dermatology, University of Pennsylvania School of Medicine
Disclosure: Received income in an amount equal to or greater than $250 from: Elsevier; WebMD.
Additional Contributors
James J Nordlund, MD, Professor Emeritus, Department of Dermatology, University of Cincinnati College of Medicine
Disclosure: Nothing to disclose.
Acknowledgements
Acknowledgments
Medscape Drugs & Diseases wishes to recognize Stephen W White, MD† for his original contributions to this article.
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