Squamous syringometaplasia in lobular panniculitis and pyoderma gangrenosum.

Squamous metaplasia of eccrine sweat glands has been most frequently described in chronic cutaneous ulcerations with associated epidermal hyperplasia. We found examples of the process in skin biopsy specimens from five patients: three had associated lobular panniculitis and two had lesions of pyoderma gangrenosum. The metaplasia was located in the mid-to-deep reticular dermis in all five patients and extended into the superficial subcutis in one. Immunohistochemical stains for CEA and S-100 protein were used to accentuate the relationship of the metaplastic islands with eccrine ducts. It is postulated that necrosis of a portion of the eccrine duct is the stimulus for this process.