Treatment Site Reactions to Zyderm Collagen Implantation

. Two cases of treatment site granulomatous reaction to Zyderm Collagen Implant that occurred in spite of a negative skin test are reported. A delayed hypersensitivity reaction to ZCI is suggested by the clinical time course and the histologic findings of hypersensitivity granulomas. Humoral immunity is also implicated in the reaction since elevated anti-Zyderm serum antibodies and plasma cell infiltrates are present. Resolution of the clinical signs and symptoms occurred over several months with no treatment. The physician using ZCI should be aware of this rare adverse reaction.