Eccrine Spiradenoma Arising in the Breast Misdiagnosed as an Epidermal Inclusion Cyst

Eccrine spiradenomas are rare, benign, cutaneous tumors that originate in the sweat glands. Eccrine spiradenomas in the breast are very rare and only a few cases have been reported. We report here on the case of a 47-year-old woman with superficial masses in the breast and these masses had gradually increased in size during follow-up. They were confirmed to be an eccrine spiradenoma on pathologic examination. There have been a few reports about the radiologic findings of eccrine spiradenomas of the breast. This is the first case of an eccrine spiradenoma in the breast that was characterized by multiple imaging modalities, including mammography, ultrasonography and MRI. The lesion in our patient was first diagnosed as an epidermal inclusion cyst based on the imaging findings and the mass's superficial location. Although the mammographic and ultrasonographic imaging findings of eccrine spiradenomas and epidermal inclusion cysts are similar, the MRI findings are different between epidermal inclusion cysts and eccrine spiradenomas. Eccrine spiradenomas should be considered in the differential diagnosis of cutaneous and subcutaneous lesions of the breast.