Discussion
NCS should be considered in differential diagnosis of patients with intermittent flank pain. According to this case, abnormally enlarged venous structures such as splenic vein which don’t have a firm consistency can be mentioned as unusual causes of NCS.
The causes of NCS are divided to three main groups:
1. Arterial causes: the most common cause of NCS is proximity of SMA to abdominal aorta (1-4). Also other arterial causes are abdominal aortic aneurysm, overarching testicular artery and ectopic ventral right renal artery
2. Retroperitoneal tumors or pathologies such as pancreatic neoplasm, chronic pancreatitis, para-aortic lymphadenopathy and decreased retro-peritoneal mesenteric fat tissue
3. Venous causes (that are very rare): LRV duplication, left renal ptosis, Left-sided IVC, hemi-azygos continuation and persistent left superior vena cava combination (as high pressure veins) (1,3,5). Splenic vein enlargement has not been reported as a cause of NCS and this is the first time that an enlarged organic vein is reported as a cause of NCS.
All of the mechanisms involved in LRV compression lead to LRV outflow obstruction (1).
In our case SMA syndrome was one of the differential diagnoses due to rapid weight loss and nausea but imaging data ruled it out (12). CT scan findings showed huge splenomegaly, splenic infarction, and enlarged splenic vein with compression effect on LRV (NCS) (Figure 1). Secondary prominency of both gonadal veins and pelvic congestion were also noticed that represented drainage of these veins through right gonadal vein in the setting of compression of LRV in NCS (Figure 2). The interesting and unique point of our case is a compression effect on LRV that has been made by an enlarged venous structure (enlarged splenic vein) without having a firm or muscular consistency, instead of the arteries or other solid pathologies. In a similar case report, the massively dilated common bile duct which hasn’t a firm structure was reported as an unusual etiology for NCS (13). The most common symptoms and signs of NCS are abdominal pain, left flank pain and hematuria (14).
As the another interesting point, abdominal and left flank pain existed in our case while hematuria as a main clinical manifestation of NCS wasn’t obtained (15).
NCS is an important diagnosis due to the significant morbidity associated with it, including the risk of chronic renal disease from long-term LRV hypertension and thrombosis (1).
Knowing about the rare etiologies can help in accurate diagnosis of NCS, which will lead to a reduction of its morbidity. To our knowledge, abnormal enlargement of a venous structure has not been reported as an etiology for NCS.
Declaration of patient consent: The authors certify that they have obtained appropriate patient consent forms.