Cutaneous mercury granuloma. A clinicopathologic study and review of the literature.

Cutaneous mercury granulomas are rarely encountered. Clinically they pose difficulty in diagnosis when there is no clear history of penetrating injury by objects containing metallic mercury. Histologic, chemical, and scanning electron microscopic studies of such cutaneous lesions were performed on four cases from the Armed Forces Institute of Pathology files. Reported cases from the literature were reviewed. Metallic mercury in tissue sections appears as dark, opaque globules, usually spherical in shape and of varying sizes and numbers. A zone of collagen necrosis often surrounds the mercury globules. A granulomatous foreign body-giant cell reaction and a mixed inflammatory cellular infiltrate composed of neutrophils, lymphocytes, histiocytes, plasma cells, and occasional eosinophils are usually present. Epidermal and dermal necrosis, with or without ulceration or pseudoepitheliomatous hyperplasia, is also a common finding. The gold lysis test and energy-dispersive x-ray analysis confirmed the presence of metallic mercury in the tissue. Following cutaneous injury from mercury, systemic toxicity may develop and death may even occur. An approach to clinical management is discussed.