Pericardial metastasis of parotid mucoepidermoid carcinoma diagnosed by pericardial biopsy.

A 30-year-old man presented with swelling in the lower left ear. Close examination led to a diagnosis of parotid gland cancer, T4N0M0 Stage IVA, so total resection of the left parotid gland and left neck dissection were performed. Pathological examination led to a diagnosis of high-grade malignant-type mucoepidermoid, and chemoradiotherapy was performed as postoperative treatment. Fourteen days after completion of chemoradiotherapy, the patient was admitted to the hospital with headache and lack of appetite. Echocardiography showed a pericardial effusion and complete collapse of the right ventricle; cardiac tamponade was diagnosed, and pericardiocentesis was performed. The pericardial effusion was bloody, and a metastatic lesion was suspected, but cytological examination showed class IIIa. On day 33 of the illness, respiratory distress and hypotension were observed. A clot was seen covering the lower wall of the heart, and dilatation of the lower wall was significantly impaired. Pericardiotomy was performed on day 36. Pathological examination diagnosed cardiac metastasis of mucoepidermoid carcinoma of the parotid gland. Although only 4 cases of parotid cancer have been reported as primary lesions of metastatic heart tumors, this case represents the world's first description of isolated parenchymal metastasis of mucoepidermoid carcinoma of the parotid gland diagnosed by pericardial biopsy.