Abstract

Renal sinus cysts are benign. Cysts involving the renal pelvis are classified as Para pelvic or peri pelvic cyst (renal sinus cyst) according to their site of origin.
Para pelvic cyst: originate from the adjacent parenchyma and protrude into the renal sinus. Histologically, they are lined with a single epithelial layer. These are simple renal cysts that extends into the renal sinus from the adjacent renal parenchyma. They are usually single or few and resemble simple renal cortical cyst in morphology.
Pera pelvic cyst: originate within the sinus itself and have a lymphatic origin. A para pelvic cyst sometimes may cause compression of the pelvicalyceal system resulting into hydro nephrosis.
Renal sinus cysts are many times diagnosed as hydro nephrosis by renal ultrasound as sometimes is it very difficult to differentiate between renal sinus cysts and hydro nephrosis. (As in this case patient presented with left loin pain).
It is very important to keep in mind that renal sinus cyst as differential diagnosis of hydro nephrosis and asking patient about his/her previous history or any previous exam. CT urography or intravenous urography very well differentiate and demonstrate a normal or narrowed/stretched/displaced (but not dilated) collecting system.

Keywords

Computerized Tomography, Contrast enhanced Computerized Tomography, Ultra sonography, Para pelvic cyst, Nephrosis, Renal Ultrasound, CT urogram, Lymph nodes, Panniculitis, Hydronephrosis, Exophytic, Mesenteric panniculitis, Distal malignancy, Pyrexia, Granulomatous disease, Rheumatic disease, Malignancies, Pancreatitis