Prurigo pigmentosa: a clinical and histopathologic study of 11 cases

Prurigo pigmentosa is a rare inflammatory dermatosis of unknown etiology. It is characterized by a recurrent pruritic rash and net like pigmentation. Most of the reported cases have been from Japan; however, here we report on several cases from Taiwan.

This was a single hospital-based retrospective study conducted in a tertiary medical center in Southern Taiwan, recruiting 14 patients with a clinical diagnosis of prurigo pigmentosa between January 1, 2000 and December 31, 2007. Clinical information was collected and reviewed, and skin biopsies were performed for all cases.

Of the 14 cases, 11 exhibited clinical and histopathological correlation with prurigo pigmentosa and were enrolled in our study. The age of the patients at diagnosis ranged from 16 to 30 years (mean, 22.3) with female predominance (female: male ratio, 8:3). Patient lesions were primarily distributed symmetrically over the chest and back area and they responded well to doxycycline treatment. The biopsy specimens of all patients showed nonspecific lymphocytic infiltration; folliculitis was noted in 7 specimens and both superficial and deep perivascular lymphocytic infiltration was found in 8 specimens.

Although far more prevalent in Japan, prurigo pigmentosa can be seen in Taiwan. In our study, patients were predominantly young females who had been initially diagnosed as having eczema. Therefore, young females who present with intractable eczema distributed symmetrically over the trunk should prompt physicians to consider prurigo pigmentosa.