Differential diagnosis between organic and inorganic mercury poisoning in human cases - The pathologic point of view

Differences in pathology were found between acute and chronic exposure to m ethylmercury, mercury vapor, and inorganic mercury. Characteristic patholog ic changes produced by organic mercury in the brain have previously been de scribed in patients with Minamata disease. The brains of patients who prese nted with acute onset of symptoms and died within 2-mo showed loss of neuro ns with reactive proliferation of glial cells, microcavitation, vascular co ngestion, petechial hemorrhage, and edema in the cerebral cortices, predomi nantly in the calcarine, pre- and postcentral, and transverse temporal cort ices and in the cerebellar cortex. The neuropathologic changes in the patie nts with acute onset of symptoms who survived for a long period (>10 yr) we re also included neuronal loss with reactive proliferation of glial cells i n similar anatomic locations. The neuropathologic changes in patients with inorganic mercury poisoning are quite different. Autopsies performed on 3 i ndividuals with fatal cases of acute inorganic mercury poisoning who were e xposed to mercury vapor for about 2 wk revealed diffuse organized pneumonia , renal cortical necrosis, disseminated intravascular coagulopathy, and inf arctions in the brain and kidneys. In 2 other patients who worked in mercur y mines for about 10 yr and who suffered from chronic inorganic poisoning, no specific lesions were demonstrated in the brain. However, the assay and the histochemistry of mercury revealed that inorganic mercury was present i n the brain in all 3 groups irrespective of the brain lesions and the durat ion of clinical signs.