Correspondence Address:
Priyadarshini Sahu
Department of Dermatology, Venereology and Leprology, Pt B. D. Sharma University of Health Sciences, Rohtak, Haryana
India

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Sir,

An 8-year-old female presented with itchy, scaly, and crusted skin lesions all over the body for 1 year [Figure 1]a, [Figure 1]b, [Figure 1]c, [Figure 1]d. History of improvement during summer, after exposure to sunlight, was present. On examination, she had multiple erythematous to lichenoid papules coalescing to form plaque in the bilaterally symmetrical reticular pattern on the trunk and both extremities. Verrucous plaques were present on the buttocks and extremities. There was hypertrophy of the periungual areas of fingers and toes, conjunctival hyperemia, and oral erosions. Routine investigations were within normal limits. Skin biopsy was advised and was consistent with the features of Keratosis lichenoides chronica (KLC) [Figure 1]d.{Figure 1}

The patient was started on NBUVB thrice weekly at an initial dose of 50 mJ/cm2 with a 10% increment of the previous dose on each subsequent visit. The patient did not achieve complete improvement, even after 1 month of NBUVB. Thus, in addition to NBUVB, the patient was started on acitretin (1 mg/kg/day). After 2 months of this combination, flattening of lesions with total healing in some areas and fading of the erythema occurred [Figure 2]. Initially, the patient was given thrice weekly for 6 months, then twice weekly for 4 months, and then weekly for the next 2 months. A total of 112 treatment sessions of Narrow band ultraviolet B (NBUVB) were given. There was complete clearance of lesions with no side effects and no recurrence during the 6 months follow-up period.{Figure 2}

KLC is a rare keratinization disorder, typically affecting adults 20–50 years of age. The disease is very rare with approximately 26 reported cases of pediatric-onset KLC till date and few from India. The cases of pediatric KLC are summarized in [Table 1].[1],[2],[3] Few cases of familial KLC are due to a germline mutation in NLR family, pyrin domain containing 1 (NLRP1). NLRP1 is an inflammasome sensor gene, which activates inflammatory cytokines such as keratinocyte growth factor, interleukin-1, and tumor necrosis factor-alpha, resulting in epidermal hyperplasia and keratosis.[4] Mucosal involvement, ocular manifestations, palmoplantar keratoderma, and nail dystrophy are reported in 20–30% of patients.[5] Along with the cutaneous lesions, ocular and oral mucosal involvement was also seen in our patient. The differential diagnosis of KLC includes lichen planus, lichen planopilaris, pityriasis rubra pilaris, mycosis fungoides, and drug eruptions.{Table 1}[7]

Cases of regression during the summer or spontaneous healing have also been reported. Our case had shown dramatic progression over time. Good results were seen in patients treated with systemic retinoids, psoralen with ultraviolet A and NBUVB.[2],[6] There are recent reports of successful use of photochemotherapy and acitretin in treating adolescent KLC patients, who had pediatric-onset KLC.[2] In our case, NBUVB might have exerted its therapeutic effect through antiproliferative and immunosuppressive mechanisms in the treatment of KLC.[4] Oral acitretin has keratolytic, antiproliferative, and anti-inflammatory effects in KLC. However, prolonged use of acitretin in children is limited by its side effects. Further, NBUVB may enhance the anti-inflammatory effect of oral acitretin and minimize the side effects by reducing the dose of both retinoids and phototherapy. Thus, we conclude that combining NBUVB with oral acitretin augments the efficacy of each other and can be used in difficult-to-treat conditions of KLC. On a detailed literature search, successful treatment of NBUVB and oral acitretin has not been reported so far, although acitretin with PUVA is a well-documented treatment for KLC.

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