Erythema papulosa semicircularis recidivans: a new reactive dermatitis?

Nine patients with recrudescent and centrifugally expanded papuloerythematous eruptions were observed in our outpatient department during the recent 8 years. The patients were all young and middle-aged men presenting with characteristic skin lesions and relapsing each year in the warm humid season. Such an observation has not yet been described in the English literature.

The objective of this study was to describe the clinical characteristics and explore the possible etiologies of our cases. In addition, differential diagnosis with other common figurate erythemas was also reviewed and discussed.

In 5 of the patients, skin-prick testing was performed with common airborne and food allergens, and skin patch testing with the Chinese baseline series of contact allergens was performed, along with histopathologic examinations.

The skin findings in our patients were conspicuous in their papular characteristics of the borders, semicircular arrangement, male predominance, and yearly crescendo of recurrence in warm seasons. Histopathologic examination showed superficial perivascular dermatitis, whereas skin-prick testing and patch testing showed negative results.

Although the etiology of our cases remains unclear at present, the clinical characteristics make them distinct from other well-described figurate erythemas characterized by annular erythematous lesions. We propose the term erythema papulosa semicircularis recidivans to depict a special form of recurrent papuloerythematous figurate erythema of unknown etiology.