Chronic thrombosis of major pulmonary arteries.

Chronic massive thrombosis of major pulmonary arteries, usually described in 0.1% of autopsies, was found in 68 of 7,753 autopsies (0.9%) in our hospital. For comparison, 201 of the 7,753 autopsies (2.6%) revealed acute-massive pulmonary emboli. The 68 cases of chronic thromboses by definition had the right, left, or main pulmonary artery occluded or severely stenosed by organized thrombi. The average age was 67; males predominated 3 to 2. Dyspnea and right heart failure were the most common clinical features, though a correct antemortem diagnosis was rare. Severe lung disease was present in 34 cases (50%); one patient (1%) had mitral stenosis. In the remaining patients, clinical thrombophlebitis had been present in 20 cases (29%), and 13 cases (19%) had no recognized related disease. When the lung disease had prominent laterality, thrombi were invariably located on the side of the most serious disease, implying propagation of smaller thrombi in diseased lung retrograde to major arteries. In bilateral lung disease or in patients without lung disease, thromboses were randomly distributed between right or left sides, suggesting an embolic origin. Assessment of the severity of pulmonary arteriosclerosis and distal arterial patency indicated that most patients could have potentially benefited from surgical thromboendarterectomy. The reason for the high incidence of chronic pulmonary artery thrombosis in our autopsy service has not been elucidated. The effects of high altitude may be important in the pathogenesis, although polycythemia was not excessive in our cases.

Vascular lesions following radiation.

The special radiation sensitivity of the vascular system is mainly linked to that of endothelial cells, which are perhaps the most radiation-vulnerable elements of mesenchymal tissues. Within the vascular tree, radiation injures most often capillaries, sinusoids, and small arteries, in that order. Lesions of veins are observed less often, but in certain tissues the veins are regularly damaged (e.g., intestine) or are the most affected structures (i.e., liver). Large arteries do suffer the least; however, when significant damage does occur in an elastic artery (e.g., thrombosis or rupture), it tends to be clinically significant and even fatal. Although not always demonstrable in human tissues, radiation vasculopathy generally is dose and time dependent. Like other radiation-induced lesions, the morphology in the vessels is not specific, but it is characteristic enough to be often recognizable. Vascular injury, especially by therapeutic radiation is not just a morphologic marker. It is a mediator of tissue damage; perhaps the most consistent pathogenetic mechanism in delayed radiation injury.

Bizarre (pseudomalignant) granulation-tissue reactions following ionizing-radiation exposure. A microscopic, immunohistochemical, and flow-cytometric study.

Two patients developed extremely bizarre (pseudomalignant) granulation-tissue reactions in the larynx and facial sinuses, following radiation therapy for carcinoma. Containing pleomorphic spindle cells and numerous (sometimes atypical) mitotic figures, both tumefactive lesions simulated high grade malignancies. While the pleomorphic cells contained vimentin immunoreactivity, they were nonreactive for low or high molecular weight keratin. Flowcytometric study of paraffin-embedded tissues revealed DNA indexes of 0.75 and 1.0. Neither recurred locally nor spread distantly after therapy. Their granulation-tissue growth pattern, and the presence of stromal and endothelial cells showing similar degrees of cytologic atypia were central to their recognition as benign. These findings show that severely atypical, sometimes aneuploid, granulation-tissue reactions can occur following radiation exposure. Care should be taken not to misinterpret these lesions as malignant.

The autopsy as a vehicle for the lifetime education of pathologists.

When the autopsy is properly performed, correctly interpreted, and thoroughly presented to the hospital medical staff, and when the diagnoses are coded and the records, slides, and other materials are appropriately stored, the autopsy is a most effective vehicle for the pathologist's lifetime continued education. It provides a continuous "refresher course" in the basic biology and pathogenesis of disease. It teaches the pathologist and, in turn, he can teach the hospital staff about injuries induced by new agents of disease, natural or iatrogenic, or those especially prevalent in his own community. In this way, the pathologist consultant to his medical staff. The autopsy provides a wealth of examples, at all stages of development, of those diseases requiring diagnosis in the surgical pathology division, as well as providing cytologic specimens of known neoplasms or malignant effusions that enhance the ability and experience of the general pathologist. Finally, correlations of autopsy findings with clinical laboratory data represent a superb quality control study of the pathologist's own clinical laboratory results.