Abstract
Eccrine syringofibroadenoma is a rare benign cutaneous neoplasm with a variety of clinical associations. Reactive eccrine syringofibroadenoma (RES), a subtype characterized by ductal hyperplasia, is thought to be caused by repeated damage to eccrine structures from chronic injury. A 62-year-old woman with a history of a motor vehicle collision over twenty years ago requiring multiple surgeries to her left lower extremity presented with a non-healing, erythematous, and warm lesion on her left plantar heel. The wound was excised with concurrent bone biopsy showing no osteomyelitis. Histopathology showed classic features of thin anastomosing strands of small and uniform basaloid cells arising at the base of the epidermis. The interconnected strands formed a lattice-like pattern in a fibrous and vascular stroma and contained luminal spaces. The underlying dermis showed numerous haphazardly distributed small ductal structures and extensive scarring. On closer examination, the ductal structures were morphologically identical to the native eccrine ducts and appeared to respect the coexisting reactive blood vessels and native eccrine glands. The proliferation stopped at the level of the dermal scarring without involvement of the subcutis. A diagnosis of RES with extensive reactive eccrine ductal proliferation was rendered. Although an infiltrative adnexal neoplasm was considered, the banal ductal cytomorphology, demarcation from underlying normal tissue, and extensive background reparative changes supported a reactive process and exclusion of a neoplasm. Reactive eccrine syringofibroadenoma is a rare, reactive process often associated with chronic, trauma-related repair. To our knowledge, this is the first reported case of RES with an additional finding of reactive eccrine ductal proliferation mimicking an infiltrative adnexal neoplasm.
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