Lichen spinulosus in Adult
Alerts and Notices
SynopsisLichen spinulosus is a rare and benign cutaneous disorder characterized by sudden onset of localized circumscribed plaques composed of follicular hyperkeratotic papules. It most frequently occurs in children and adolescents; however, young adults can also be affected. There is a slight male preponderance. Individuals of any race can be affected. The etiology and pathogenesis are not known, although atopic, infectious, and genetic factors have been proposed as causes. Patients often have a history of atopy. An actinic variant has been described in which patients suddenly worsen in the summer or present following acute prolonged ultraviolet (UV) exposure, such as attending outdoor sporting activities.
Although usually localized to certain sites of predilection, a more severe generalized variant of lichen spinulosus also exists. This variant occurs in association with nodulocystic acne and pityriasis rubra pilaris as part of type VI (HIV-associated) pityriasis rubra pilaris. Additional rare associations include Crohn disease, Hodgkin disease, seborrheic dermatitis, syphilis, id reactions to fungal infections, and heavy metal ingestions. Note that these associations are not causal relationships and may be the consequence of ascertainment bias.
Lichen spinulosus has a variable course. Most cases tend to resolve spontaneously at puberty; however, persistent cases have also been described. Although no treatment is required, effective therapeutic options include topical keratolytic agents and topical retinoids.
L73.8 – Other specified follicular disorders
4859009 – Lichen spinulosus
Differential Diagnosis & Pitfalls
- Keratosis pilaris – occurs with much greater frequency, has more gradual onset, appears more diffusely (not in circumscribed plaques), preferentially affects the extensor upper arms and legs, and often has a seasonal variation (improves in summer, worsens in winter).
- Pityriasis rubra pilaris, especially type IV (circumscribed juvenile) – more erythematous, primarily affects the elbows and knees, resembles localized psoriasis, and may be associated with palmoplantar keratoderma.
- Frictional lichenoid eruption – tends to affect children only (especially those in their first decade of life); occurs almost exclusively on the dorsal hands, elbows, and knees; and repetitive exposure to significant frictional force during play (ie, contact with abrasive material such as sand, grass, or carpet) is often elicited from history.
- Folliculotropic mycosis fungoides or follicular mucinosis – look for widespread involvement, alopecia, and non-response to standard therapy.
- Lichenoid drug eruptions, including actinic variants.
- Lichen nitidus – usually presents with discrete, flat topped, shiny papules on the trunk and inguinal area; however, cases with co-existent histologically confirmed lichen spinulosus have been reported.
- Follicular eczema – fine papules scattered on the trunk and extremities; also consider follicular id dermatitis.
- Phrynoderma (hypovitaminosis A, or vitamin A deficiency) – rare in developed countries except in the setting of intestinal malabsorption or anorexia nervosa, and associated systemic findings are often present.
Lichen spinulosus in Adult