A Clinical and Histopathological Study of 27 Cases of Prurigo Pigmentosa / 대한피부과학회지

ABSTRACT

BACKGROUND: Prurigo pigmentosa is a rare recurrent inflammatory disease of the skin, and this is characterized by an abrupt onset of erythematous papules that usually resolve with leaving reticular hyperpigmentation. Although its incidence has increased in Korea as well as in the international community, there are few comprehensive studies on this malady in the Korean dermatologic literature. OBJECTIVE: The purpose of this study was to evaluate the clinical and histopathological features of prurigo pigmentosa. METHODS: We reviewed all the medical records, photographs and histopathological slides of 27 patients who had been diagnosed with prurigo pigmentosa at 3 hospitals between 1998 and 2009. Additionally, we also reviewed the clinical findings of the 37 cases that have been reported in the Korean dermatologic literature. RESULTS: The ratio of males to females was 12.4 and the mean age of onset was 24.6+/-8.2 years old. Twenty six patients (96.3%) complained of pruritus that was usually moderate to severe and the most commonly involved site was the back (63.0%). Although all 27 patients presented with erythematous papules, the skin lesions were accompanied with reticulated hyperpigmentation in 17 patients (63.0%) at the time of diagnosis. Fourteen patients were treated with minocycline alone or in combination therapy, and two pregnant women were treated with topical steroid alone. The major microscopic features of the lesions of prurigo pigmentosa were mild to moderate acanthosis and spongiosis in the epidermis, extravasation of erythrocytes and a mild to moderate perivascular lymphohistiocytic infiltrate in the dermis. A neutrophilic infiltrate tended to be observed in the relatively early lesions rather than in the fully developed lesions. CONCLUSION: Clinicopathologic correlation and thorough long-term follow-up are necessary to establish a diagnosis of prurigo pigmentosa because a pathologic examination does not show pathognomonic features. Our data suggest that neutrophils may play a role in the pathogenesis of prurigo pigmentosa, based upon finding them in the early lesion and the efficacy of the agents that inhibit neutrophil function, such as dapsone or minocycline.