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Keratosis lichenoides chronica (KLC) is a rare acquired disease of adulthood, of unknown etiology, characterized by keratotic parallel linear lesions, retiform plaques, and keratotic, often follicular papules, chronicity and lichenoid histopathologic features. KLC of pediatric onset is considered extremely rare. Its features and relationship to adult onset KLC are unknown. We studied 8 cases of pediatric-onset KLC in the literature and 6 personal cases and compared them with 40 reported adult-onset KLC patients. The following features characterize pediatric-onset KLC: familial occurrence; probable autosomal recessive inheritance; early or congenital onset with facial erythemato-purpuric macules; forehead, eyebrow, and eyelash alopecia; pruritus; and a low frequency of other cutaneous and systemic abnormalities. Pediatric-onset KLC may represent a different disease or a subset of adult-onset KLC, with special genetic and clinical characteristics. Determining its precise nosology will have prognostic and therapeutic implications.

Lichenoid eruptions are quite common in children and can result from many different origins. In most instances the precise mechanism of disease is not known, although it is usually believed to be immunologic in nature. Certain disorders are common in children, whereas others more often affect the adult population. Lichen striatus, lichen nitidus, Gianotti-Crosti syndrome, and lichen spinulosus are examples of lichenoid lesions that are more common in children than adults. Distinguishing these diseases is necessary for prediction of the course of the eruption and for optimal management. In most cases, certain clinical characteristics enable the clinician to reach a diagnosis, whereas in other cases biopsy is required for a definitive answer. Many of these lesions are self-limited and only require symptomatic treatment, although corticosteroids can hasten resolution in certain disorders. Discontinuation of the medication is often sufficient for resolution of lichenoid drug eruptions.

Background: Lichenoid dermatoses are composed of a wide spectrum of disorders with a common histopathologic interface pattern but diverse causes and pathophysiology., Objective: We describe a series of young patients with a peculiar annular lichenoid dermatitis, the clinical appearance of which initially suggested diagnoses of morphea, mycosis fungoides, or annular erythema., Results: The study involved 23 patients (median age 10 years; age range 5-22 years). Lesions consisted of persistent asymptomatic erythematous macules and round annular patches with a red-brownish border and central hypopigmentation, mostly distributed on the groin and flanks. Histology revealed a peculiar lichenoid dermatitis with massive necrosis/apoptosis of the keratinocytes limited to the tips of rete ridges, in the absence of dermal sclerosis and epidermotropism of atypical lymphocytes. The infiltrate was composed mainly of memory CD4(+) CD30(-) T cells with few B cells and macrophages. Analysis of T-cell receptor-gamma-chain gene rearrangement in skin biopsy specimens revealed polyclonality in all the 15 cases studied. Topical and systemic corticosteroids or phototherapy were effective in most patients with relapse after treatment withdrawal., Conclusions: We suggest that this is a distinctive inflammatory condition, and we propose to term it "annular lichenoid dermatitis of youth."

A 7-year-old girl had erythematous hyperkeratotic papules and plaques that improved in summer and recurred in winter since the age of 4 months. She had had irregular, ridge-like erythematosquamous lesions on the arms with the same seasonal variation. The lesions on the arms improved with age. Light and electron microscopic examination showed marked degeneration of keratinocytes and prominent apoptosis. Her older brother had a similar but milder dermatosis. We believe these cases may represent a variant of keratosis lichenoides chronica.