Chronic pityriasis lichenoides – a case discussion

Abstract

The term Pityriasis lichenoides encompasses a group of inflammatory skin diseases of unknown cause, clinically presented as macules, papules, or erythematous-squamous plaques. The current classification distinguishes between pityriasis lichenoides et varioliformis acuta (PLEVA) and pityriasis lichenoides chronica (PLC). PLC is considered a benign form within the class of lymphoproliferative pathologies, with a more frequent onset in young individuals. The aim is to present two cases of familial PLC, highlighting their particularities, the prolonged evolution of the lesions, and the genetic susceptibility to the disease. Materials and Methods Two cases of familial PLC are presented, involving a mother and daughter, with diagnoses established clinically and histologically. Case presentation A 16-year-old patient and her 43-year-old mother presented at the Dermatology Hospital with complaints of persistent papulo-squamous lesions, accompanied by moderate, intermittent pruritus. The daughter’s lesions appeared at the age of 8 and showed a prolonged evolution, with periods of remission and exacerbation. At the time of presentation, they manifested as erythematous, round-oval papules, 0.3 – 1 cm in diameter, well-defined, with a surface covered by fine, easily detachable scales, disseminated on the trunk, upper, and lower limbs. She underwent multiple courses of topical corticosteroid treatment without lasting improvement. The mother’s lesions appeared 8-9 months prior, presenting as erythematous-squamous papules with a diameter of 0.5-2 cm, well-defined, with fine scales. Laboratory investigations for both patients did not detect any abnormalities. Histopathological examination revealed a similar picture in both clinical cases: parakeratosis, moderate acanthosis, spongiosis, atrophy foci, moderate lymphohistiocytic inflammatory infiltrate of the dermis. A diagnosis of PLC was established, and topical corticosteroid treatment and UVB Narrow Band phototherapy were indicated. After 8 weeks without a therapeutic effect, oral treatment with prednisolone 0.6 mg/kg/24 h for 30 days with gradual dose reduction and doxycycline 100 mg/24 h for 10 days was indicated. For the mother, oral prednisolone 0.5 mg/kg/24 h for 30 days, plaquenil 400 mg/24h for 20 days, then 200 mg/24h for 40 days were administered. After 2 weeks, most lesions were in remission. Discussion PLC is considered a benign condition with a favorable prognosis, characterized by self-limitation and spontaneous remission. The main differential diagnosis is lymphomatoid papulosis, with histopathological examination being the defining criterion. Annual reevaluation of patients with PLC diagnosis is necessary due to the possible progression to mycosis fungoides, cases of which are described in the literature. The peculiarity of this case lies in the occurrence of PLC in 2 generations. The prolonged evolution of the lesions, which are poorly responsive to topical corticosteroid treatment, with exacerbations during the cold season when sun exposure is reduced, is noteworthy. Upon discontinuation of corticosteroid application, new lesions appear and existing ones worsen. Conclusions PLC diagnosis is clinical, confirmed by histopathological examination. Long-term clinical monitoring of patients with PLC is recommended, with examination of skin biopsies in case of lesion evolution, due to the risk of progression to mycosis fungoides.