[Small-plaque parapsoriasis: case report]

Small plaque parapsoriasis is a relatively rare, chronic, idiopathic dermatosis, most often seen in middle age people. This disease shows a definite male predominance of approximately 3-4: 1. It is characterized by presence of round or oval erythematous, slightly scaly plaques on the limbs and trunk, which histologically reveal mild eczematous changes.

A male patient, 61 years of age, was admitted to the Clinic of Dermatovenereology in Novi Sad due to long persisting erythematous patches on his upper and lower limbs. Plaques were of oval and round shape, pretty well marginated. They were of light red colour, covered with fine scales with a slightly wrinkled surface. He complained of itching. Laboratory findings showed no abnormalities. Histopathologic examination of the skin specimen revealed epidermal atrophy, focal parakeratosis, perivascular dermal infiltrate of mononuclear cells with exocytosis in the epidermis. This finding was compatible with the clinical diagnosis. After treatment with topical corticosteroid cream combined with whole body exposure to sunlight irradiation, vast majority of skin lesions regressed.

The clinical course of small plaque parapsoriasis is very long. The plaques are remarkably stubborn, responding to treatment with steroid creams or to natural or artificial sunlight, but usually reappearing promptly when treatment is discontinued. The patches increase in number for a time, and then remain relatively constant for a long time. A small minority of cases clears entirely. Recent studies provided evidence of monoclonality and immunophenotypic abnormalities. Rearrangement of T-cell receptor genes was demonstrated by using PCR method. Detection of monoclonal T-cell populations in skin lesions, as a characteristic of lymphoproliferative diseases, forced some authors to include this dermatosis into a group of abortive cutaneous T-cell lymphomas.

This case deserves a long and probably life-long clinical and histological assessment, especially due to new knowledge about the possible nature of this disease.