Segmental Arterial Mediolysis: A Multiguised Vasospastic Arteriopathy with Collateral Mesangial Cell Hyperplasia and Cardiac Toxicity Generated by Norepinephrine and Hyperdense Adrenoceptors Alone or by Crosstalk with Other Pressor Agents.

Segmental arterial mediolysis (SAM), an uncommon vasospastic arteriopathy occurring in the muscular arteries innervated by the peripheral sympathetic nervous system, usually presents with catastrophic abdominal and retroperitoneal hemorrhages in elderly patients. SAM is initiated by the coupling of norepinephrine to plastically derived hyperdense foci of alpha-1 adrenergic receptors on the sarcolemma of arterial muscle. This ligand is created by stimuli signaled by iatrogenic sympathomimetic agonists, some beta-2 agonists, or an excessive release of adrenal catecholamines.

Tumoral calcinosis--a pathogenetic overview: a histological and ultrastructural study with a report of two new cases, one in infancy.

Tumoral calcinosis occurs as a well-defined pathologic entity in 3 heterologous groups of diseases--hyperphosphatemic familial tumoral calcinosis, normophosphatemic tumoral calcinosis, and secondary tumoral calcinosis. The histological lesion is stereotypic developing from the concurrence of a juxta-articular injury with an elevated calcium-phosphorus product. The reparative response to injury is histiocytic featuring synovial metaplasia forming bursa-like structures that create the characteristic compartmentalization of the lesion.

Segmental arterial mediolysis--an iatrogenic vascular disorder induced by ractopamine.

Background: Segmental arterial mediolysis, an uncommon arterial disorder most often occurring in the splanchnic muscular arteries of the abdomen, is a cause of catastrophic hemorrhages. Its histology and initial clinical presentations suggested that it represented a localized norepinephrine-induced vasospastic response to perturbations in vascular tone and blood volume distribution caused by coexisting vasoconstrictor conditions. However, later presentations were at odds with some aspects of this hypothesis.

Segmental arterial mediolysis: course, sequelae, prognosis, and pathologic-radiologic correlation.

Background: Segmental arterial mediolysis is a vascular disease of putative vasospastic origin that causes massive hemorrhages. Although once considered rare, awareness of this disease has resulted in increased reports in the pathology and radiology literature. Despite this, uncertainties concerning pathologic and radiologic correlations, the course of this disease, and aspects of its prognosis exist.

Segmental arterial mediolysis with accompanying venous angiopathy: a clinical pathologic review, report of 3 new cases, and comments on the role of endothelin-1 in its pathogenesis.

The authors review 20 cases of segmental arterial mediolysis (SAM) including 3 newly reported cases. SAM developed in areas of vascular distention in 2 of the latter cases: 1 in utero in the heart of a recipient of a twin transfusion syndrome and the other in the jejunum secondary to partial venous obstruction. In the third case, it occurred in a patient with Raynaud disease.

Expression of vascular endothelial growth factor and receptor flk-1 in colon cancer liver metastases.

Background/purpose: This study investigated vascular endothelial growth factor (VEGF) and flk-1 expression in hepatic metastases from colon carcinoma, and their associations with tumor angiogenesis, proliferation, and apoptosis.

Methods: Immunohistochemical studies were performed for VEGF/flk-1, Ki-67, p53, and bcl-2 expression, and microvessel density (MVD) in surgical specimens from 35 patients who underwent hepatectomy for colon cancer liver metastases between 1986 and 2001.

Results: VEGF and flk-1 were expressed mainly in the cytoplasm of tumor cells.

The seromuscular tear and other intestinal lesions in the seatbelt syndrome: a clinical and pathologic study of 29 cases.

The authors describe the clinical and pathologic findings in 29 patients with injuries from motor vehicle accidents. The seromuscular tear (SMT), the hallmark intestinal injury of the seatbelt syndrome, is an unambiguous lesion similar in all segments of bowel and is caused by a tear that separates the inner muscularis from the submucosa. It is characterized by (1) a wedge that strips the submucosa from the inner circular muscle; (2) a bending retraction of the torn muscularis toward the uninvolved bowel wall; (3) mucosal-submucosal fold effacement, causing the mucosa-submucosa bridge spanning the tear to become paper thin; and (4) the vulnerability of this bridge to ischemia that in 35% of the tears studied culminated in incipient or frank perforations and/or gangrene.