Introduction: Epidermoid syringometaplasia consists in rare changes of the eccrine sweat glands, which show keratinization of their ductal part. Many conditions are associated with epidermoid syringometaplasia: chronic ulcers, scars, keratoacanthoma and various drugs or toxic agents, suggesting a toxic effect of drugs or an inflammatory mechanism.
Observation: A 22-year-old woman presented with large painless ulcero-vegetating lesions of the forearm; the X-ray examination showed an major emphysema. She also had multiple scars on her trunk and limbs. The curious features of the lesions and the psychiatric troubles suggested the diagnosis of dermatitis artefacta. Histopathological examination showed a pseudocarcinomatous epidermal hyperplasia; in the deep dermis the eccrine ducts were connected to the epidermal cell masses or seemed to be included into the proliferation. Keratinization was noted within the keratinocytes surrounding the duct lumen. A dense inflammatory cell infiltrate was observed, containing many macrophages with a foamy cytoplasm, probably resulting from the injection of a foreign substance. All lesions healed within a few days using an occlusive dressing.
Comments: In this patient, the voluntary injection of an unknown substance probably induced these metaplastic changes of the sweat ducts, which are probably related to a toxic mechanism. Epidermoid syringometaplasia has never been described after cutaneous injections.