Superficial granulomatous pyoderma: a case report of two Japanese patients and clinical comparison with foreign patients

Superficial granulomatous pyoderma (SGP) is an unusual variant type of pyoderma gangrenosum characterized by a benign course and specific histological features; it is quite a rare cutaneous disorder in Japan. We reported two Japanese cases of SGP and compared the clinical features of 13 Japanese cases with those of 42 foreign cases. Case 1 was a 53-year-old female who presented with three indolent and ulcerative plaques with elevated edges on the back and the posterior portion of the left thigh. Case 2 was a 74-year-old female who presented with crusted and vegetative erythematous plaques on the left shoulder and left upper arm. Histological examinations revealed a characteristic three-layer granuloma in each case. Laboratory and physical examinations found no abnormalities. Topical corticosteroid, oral administration of minocycline, and/or additional supplementation with corticosteroid were effective. In comparison with foreign cases, Japanese cases show a possible differentiation in the ratio of sex and distribution of the ulcer. Females have a high incidence and the extremities are frequently involved area in Japanese cases. Up to now, 11 cases of SGP have been reported in Japan. To our best knowledge, our patients are the first Japanese cases described in the English literature.