With these findings, the definitive pathological diagnosis changed from cystic nephroma to MCRCC with a Fuhrman grade of 1, with surgical margins negative for neoplasia.
Benign renal masses can also be part of the differential diagnosis of MCRCC.
The diagnostic evaluation of patients with MCRCC is troublesome before surgery due to the nonspecific radiological findings of this pathology.
According to these findings, some studies have tried to differentiate between MCRCC of other cystic RCC.
In our case the reported HU in the corticomedullary phase were 37 HU, thus supporting the fact of facing a MCRCC.
11] tried to improve the accuracy of preoperative diagnosis between CN and MCRCC.
In CN, there are focally distributed clear cells in the surface of the septa, hobnail epithelium, ovarian-like stroma, and mature tubules in the septa, whereas evident solid areas in cystic mass or extensile nodules of clear cells favor MCRCC [12, 13].
14] compared 19 cases of MCRCC versus other cystic kidney lesions and 22 benign simple cortical cysts as controls.
Therefore we can assume that useful immunohistochemical staining for EMA, CK7, and CA-IX may be helpful in establishing a more accurate diagnosis and differentiating other cystic lesions from MCRCC as we saw in our case.
The diagnostic rarity of finding a completely cystic renal cell carcinoma and the excellent prognosis of MCRCC
compared with the other variants of RCC differentiate it, and few authors have suggested renaming it as multilocular cystic renal cell neoplasm of low malignant potential.