Bilobed spleen, transposition of the inferior vena cava and Riedel lobe: an extremely rare imaging finding in the same case

There is a wide range of congenital anomalies of the spleen regarding its shape, location, number, and size. Most of these congenital anomalies are commonly detected on ultrasonography, CT, or MRI and may sometimes represent a challenging diagnosis for radiologists and clinicians. The bilobed spleen is an extremely rare form of congenital anomaly. In most cases, it is accidentally discovered during abdominal surgeries. The bilobed spleen is usually large in size when compared with the normal spleen; hence, it is more liable to trauma. Transposition of the inferior vena cava (IVC; also known as left-sided IVC) refers to a very rare variant course of the IVC. The most common variations are duplicate IVC, as well as retroaortic left renal vein and circumaortic venous rings. Left-sided IVC occurs in 0.17–0.5% of the general population. Diagnosis of left-sided IVC is important when planning vascular procedures like portosystemic shunt, the placement of an IVC filter, nephrectomy, and renal transplant. There should be an awareness of the Riedel lobe, which is a common anatomical variant of the liver, as it can simulate a mass. Its misidentification as a pathological abdominal mass can lead to surgery; pathology can also occur (e.g. malignancy or even torsion). In this report, we presented a case of a bilobed spleen that was misdiagnosed as a left renal mass during routine abdominal ultrasonography in a 25-year-old female who complained of recurrent left hypochondrium pain. The bilobed configuration was confirmed with MRI and ultrasound examination of the abdomen.