Myxoma of the renal pelvis masquerading pelviureteric stenosis: conservative limited resection with renal preservation: case presentation and literature review

Abstract

Background: Myxoma is a relatively rare mesenchymal tumor seen mainly in the heart and skin. Renal myxomas in particular are exceptionally rare where only 17 cases were previously reported in the English Language literature. Only 2 of the 17 reported cases were located in the renal sinus/pelvis. Case presentation: This is a case of an 18-year-old male patient who complained of right, colicky flank pain associated with abdominal pain and discomfort. Imaging findings revealed right kidney hydronephrosis with a provisional diagnosis of pelviureteric junction (PUJ) stenosis. On computed tomography, there was a very faint thin walled mass abutting the calyces, camouflaged within the dilated renal pelvis. During surgery, a polypoid mass was found at the pelviureteric junction, causing the obstruction. Histological examination showed a hypocellular, paucivascular myxoid neoplasm, with few spindle cells displaying serpentine nuclei and inconspicuous nucleoli. The tumor cells expressed immunoreactivity for vimentin, but not for S100, CD34, actin, or desmin. This will qualify as the third case of renal pelvis myxoma. Conclusion: Myxomas in the renal pelvis/sinus are extremely rare and can present with hydronephrosis and subtle radiological findings mimicking a PUJ stenosis. Being aware of this entity can save the patient unnecessary nephrectomy with possible preservation of the kidney.

Myxoid Pseudotumor Involving the Renal Sinus

“…Primary neoplasms of the renal sinus are rare and can originate from any of the tissue elements present 1. Examples include angiomyolipoma, anastomosing hemangioma, “myxoma,” solitary fibrous tumor, leiomyoma, lymphoma, immunoglobulin (Ig) G4–related disease, and well-differentiated/dedifferentiated liposarcoma 2–9. Myxoid lesions of the renal sinus, in particular, may present a diagnostic challenge because although myxoid liposarcoma occurring in the retroperitoneum is rare,10 well-differentiated liposarcoma with myxoid change is not infrequent in this location, including in perirenal soft tissue 11…”

“…1 Examples include angiomyolipoma, anastomosing hemangioma, "myxoma," solitary fibrous tumor, leiomyoma, lymphoma, immunoglobulin (Ig) G4-related disease, and well-differentiated/dedifferentiated liposarcoma. [2][3][4][5][6][7][8][9] Myxoid lesions of the renal sinus, in particular, may present a diagnostic challenge because although myxoid liposarcoma occurring in the retroperitoneum is rare, 10 well-differentiated liposarcoma with myxoid change is not infrequent in this location, including in perirenal soft tissue. 11 Tanas et al 12 described a pseudosarcomatous fibroblastic/myofibroblastic proliferation in the perinephric adipose tissue in nephrectomy specimens with renal cell carcinoma.…”

Myxoma of urinary bladder (case report)

“… 3 Many cases have been reported in the kidney; whereas, nephrectomy has been reported due to suspicion to malignancy, in the follow up of the patients there had been no sign of malignancy, such as metastasis and recurrence. 5 …”