Bilateral persistent sciatic vein: report of a case with developmental, histological and clinical aspects.

OBJECTIVE: Bilateral large variant veins were encountered in the lower extremity. It was aimed to identify the structural characteristics of this rare case and then, regarding the structural features, to overview its formation process and denomination. MATERIAL AND METHOD: During the routine dissection of a 93-year-old male cadaver, bilateral large variant veins were found at the thigh. Valves of the veins were examined and evaluated together with the vascular wall histology. RESULTS: The variant vein was loosely attached to the sciatic nerve by fibrous tissue and had anastomoses with the popliteal vein in the popliteal fossa on each side. The popliteal veins were hypoplastic on both sides. The right variant vein was passing through the fibers of the adductor magnus muscle 56.2 mm above the adductor hiatus, which corresponds to the third perforating branch of deep femoral vein. The left one was turning to the front over the adductor magnus muscle, at the lower border of quadratus femoris muscle. The left variant vein was corresponding to the descending branch of the medial circumflex femoral vein. Both variant veins had one incomplete and three well-developed valves. CONCLUSION: In accordance with the findings, the variant vein was concluded to be an embryonic remnant, rather than an acquired one subsequent to any obstruction of the femoral vein. Regarding their connection with the popliteal vein but not with the internal iliac vein, both variant veins were denominated as "lower type persistent sciatic vein". Such a variation would be important with respect to the risk of complication during popliteal sciatic nerve blockade.

Ultrastructure of popliteal vein aneurysm.

The term aneurysm is used to indicate a permanent and irreversible localized vascular dilatation that involves all three layers of the blood vessel wall. It may develop in any part of the circulatory system, including veins, and its history, presentation, and management differ depending on the location. A venous aneurysm is defined as a solitary area of fusiform or saccular dilatation occurring in the course of a major vein or connected by a single channel to a major venous structure. The lower extremities are the most frequently affected, with the popliteal vein being the most common site. Although different theories have been advanced, the etiology of the disease remains uncertain. Mechanical stress and/or degenerative changes within the vein wall are believed to represent the most likely causes of venous aneurysm. To date, there are only a few publications dealing with the histological appearance of popliteal vein aneurysm, and no studies that specifically describe its ultrastructural details have been published to our knowledge. In an attempt to fill this gap and to provide better insights into the pathophysiological mechanisms possibly involved in aneurysmal venous disease, we describe the fine structure of popliteal vein wall and valve in health and disease using both scanning and transmission electron microscopy.

Histopathology of veins and venous valves of patients with venous insufficiency syndrome: ultrastructure.

Vein and vein valve biopsies were obtained from venous insufficiency syndrome (VIS) patients undergoing venous valve transplants. Normal control biopsies were obtained from other non-VIS procedures. The specimens were examined using light and transmission electron microscopy (TEM). Biopsies from VIS patients showed a variety of changes from what was considered normal structure. Most histopathologic changes were noted in the endothelium and subendothelial layer of the vein valve and wall, and in the media of the vein wall. These changes included 1) erosion of the endothelium with consequent adherence of blood elements, 2) intact endothelium with a thickened subendothelial zone which was populated with migrated smooth muscle and perhaps other cell types, 3) occurrence of abnormal or over-abundant collagen, and 4) thickening of the media with changes in the smooth muscle population therein.