A Case of Eccrine Syringofibroadenoma Related to Senile Gluteal Dermatosis

Eccrine syringofibroadenoma (ESFA) is a tumor of eccrine ductal differentiation. ESFA is a rare disease, with only approximately 80 cases reported worldwide. ESFA can be classified into five subtypes. Senile gluteal dermatosis (SGD) was first reported in Japan in 1979. It is a relatively common geriatric dermatosis in East Asia, and characterized by hyperkeratotic lichenified skin lesions in the gluteal region. An 86-year-old woman presented with a solitary recurrent dark brown plaque in the sacral area. There was a hyperkeratotic lichenified brownish patch around the plaque, which was clinically considered SGD. Histopathological examination of biopsy specimen revealed thin anastomosing reticulated strands of basaloid cuboidal cells. The tumor extends from the basal layer of the epidermis to the dermis. These findings are consistent with those of ESFA. The patient was treated with total excision of the skin lesion. Reactive ESFA is related to tissue regeneration and remodeling after damage, such as trauma and burns. There is no literature reporting ESFA related to SGD so far, but there have been few reports of cases occurring in soles or buttocks, which are constantly under pressure. This is the first report on reactive ESFA related to SGD, and further research is needed to reveal the pathogenic mechanism.