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Q1: What is the likely diagnosis?
This is a case of metallic mercury embolism, after intravenous self administration of metallic mercury by the patient, who is a chemist, with suicidal intent.
Q2: What is the differential diagnosis?
In most reported cases, the presence of metallic mercury in the tissues was demonstrated by radiography, the metal being either at the site of introduction or in the form of emboli in the lung. The chest radiographs of patients with pulmonary mercury emboli are striking and reveal numerous abnormal metallic densities scattered throughout both lungs, mostly in the periphery. However HRCT findings have been described only in a few cases.1 HRCT of the thorax in this patient revealed multiple hyperdense foci clustered in the periphery of both lungs, more so in the lower zones; similar hyperdensities were also seen in the right ventricular apex. The diagnosis of mercury emboli is suggested by the density, size, and characteristic spherical shape of the mercury droplets. Pulmonary emboli occurring after lymphangiography or hysterosalpingography exhibit a diffuse haziness and are less dense. The presence of aspirated barium or bronchography contrast media may be diagnosed by their more linear nature, by review of previous radiographs, and by clinical history. Distinguishing between pulmonary emboli and aspirated intrabronchial mercury may be the most difficult. The presence of intraintestinal mercury suggests mercury aspiration. Identification of associated intracardiac mercury and mercury in the abdominal vessels and subcutaneous tissue of the extremities would indicate a diagnosis of mercury embolisation.
Mercury embolisation of the lungs is rarely reported.2 Pulmonary embolisation may be accidental or intentional—accidently from injury from a broken thermometer or from venous blood sampling with mercury sealed syringe, and intentionally from injection by drug abusers “for kicks”, or with suicidal intent.3 This patient tried to commit suicide by injecting metallic mercury (2.5 ml) from a broken thermometer, five days before admission. The metal reaches the right ventricle and is disseminated throughout the pulmonary tree. Roentgenographically, the appearance is distinctive because of the very high density of mercury, in the form of bilateral spherules or short tubular structures representing mercury filled arterial segments. Roentgenographs of the abdomen may reveal scattered mercury deposits as in this patient, due to passage into the systemic circulation via shunts.4-6 Multiple metallic densities in the lungs suggest mercury emboli as well as aspiration. Radiographic examination of possible injection sites and detailed history and evaluation of the chest, abdomen, and extremities can provide important evidence of intravenous administration. The presence of mercury in the right ventricle strongly suggests intravenous embolisation. Metallic mercury causes local chronic inflammation, however mercurialism—the clinical syndrome associated with mercury salt intoxication—has not been reported commonly with elemental mercury injection hence treatment with chelating agents such as dimercaprol (British antilewisite) and penicillamine is usually not warranted,5 as in this patient. Metallic mercury in the tissues is thought to undergo slow biological oxidation and may remain unchanged on chest radiography up to one year after injection, disappearing gradually.6 ,7
Metallic mercury pulmonary embolism.