Absence of Evidence for a Significant Background Incidence of Diffuse Malignant Mesothelioma apart from Asbestos Exposure

The incidence of diffuse malignant mesothelioma is rising. Physicians can diagnose a disease only when they know that it exists, so one explanation for the rise in incidence is more widespread appreciation of the clinical and pathological features of the disease. Modern pathology has ascribed specific requirements for the diagnosis of diffuse malignant mesothelioma. A priori one cannot assume that these requirements have increased the likelihood of the diagnosis because the requirements also can serve to exclude the diagnosis depending on the findings. Most cases of diffuse malignant mesothelioma are suspected by macroscopic and routine microscopic techniques that have been available since the last part of the nineteenth century. Although single reported instances of some pulmonary diseases have survived from the nineteenth century, pathologists did not identify enough cases to convincingly establish the existence of diffuse malignant mesothelioma of the pleura as an entity until the 1930s or 1940s. One must conclude that the background level of diffuse malignant mesothelioma in Europe and in the United States prior to 1930 was extremely low. No case was detected at the Massachusetts General Hospital until 1946.