Venous thrombosis in rare or unusual sites: a diagnostic challenge.

Venous thrombosis usually involves the veins of the limbs, most frequently the leg veins. All other venous districts may sometimes be affected by the thrombotic process. Sometimes, the thrombotic occlusion of the veins of a given region show typical signs and symptoms. In other cases, the picture may not be clear and a high degree of clinical suspicion is needed for a correct approach to patient diagnosis and management. Thrombosis of retinal and jugular veins, right heart thrombosis including thrombosis of coronary sinus and thrombosis of the azygos system may be included in this group. In addition, thromboses of umbilical, renal, ovarian, spermatic, and iliac veins also require attention. Finally, the dorsal veins of the penis may also be affected by thrombotic events. The main clinical features of these thromboses are reviewed herein with suggestions for a correct diagnostic approach. The importance of sonography and of other imaging techniques is emphasized. A prompt diagnosis is of paramount importance as most of these thromboses in rare or unusual sites may still cause severe systemic complications (pulmonary embolism, sepsis, and heart failure).