Clinical, Pathological, and Dermoscopic Features of Pityriasis Rotunda / 대한피부과학회지

ABSTRACT

Background@#Pityriasis rotunda (PR) is a rare dermatosis characterized by the presence of multiple, strikingly circular or oval-shaped, sharply demarcated, and scaly hyperpigmented patches. Its etiology remains poorly understood. To date, there have been no comprehensive analyses of PR in Koreans. @*Objective@#To investigate the clinical, pathological, and dermoscopic features of PR. @*Methods@#Sixteen patients with PR were evaluated. @*Results@#A female preponderance was observed (malefemale ratio 17), and the mean age of the patients was 33.2±16.1 years (range, 15∼68 years), with the peak incidence observed in patients in their 20s. Notably, all the lesions developed on the trunk. The most common clinical diagnosis is PR. Histologically, PR appears similar to ichthyosis vulgaris. Hyperkeratosis was mainly ortho-keratotic, with plugs observed within hair follicles, elongated rete ridges, diminished stratum granulosum, enhanced pigmentation of the basal layer, pigmentary incontinence, and sparse superficial perivascular lymphoid cell inflammatory infiltrate. Periodic acid-Schiff staining was negative for fungi. Hyperpigmented patches with occasional scales were separated from each other by paler striae on dermoscopy. @*Conclusion@#PR commonly presents as multiple round lesions of variable sizes on the trunk of patients in their 20s. They showed characteristic findings, including hyperkeratosis with relative focal hypogranulosis, histopathologically, and some lesions showed dark and light brown polygonal patches with paler striae arranged dermoscopically, in a mosaic pattern. This was a retrospective single-center study with a small sample size; however, we believe that this paper will contribute to the clarification and understanding of PR.