De subitaneis mortibus. XIX. On the cause of sudden death in pheochromocytoma, with special reference to the pulmonary arteries, the cardiac conduction system, and the aggregation of platelets

Pheochromocytoma may cause sudden and unexpected death. In this study of three fatal cases of pheochromocytoma the small pulmonary arteries were narrowed by a variety of chronic and acute processes which included medial hypertrophy and fibrosis, endothelial proliferation and fibrosis, and endothelial cellular edema; within the sinus node, atrioventricular (A-V) node and His bundle of all three cases there was focal degeneration and fibrosis similar to that also observed throughout the ventricular myocardium; and in addition to the focal narrowing of many small coronary arteries produced by medial hypertrophy, intimal fibrosis, and fibromuscular dysplasia, there were also focal aggregations of platelets clogging the lumen and occasionally mixed with a varying amount of fibrin. In patients known to have pheochromocytoma it may be necessary to direct new attention to the possibility of abnormal pulmonary vascular resistance, instability of normal cardiac rhythm, and perhaps difficulty in restoring it when disordered and to the effects of platelet aggregations, both causing acute obstruction and possibly contributing to the pathogenesis of chronic vascular disease.