CASE 9599 Published on 07.11.2011

Unclassified renal cell carcinoma: CT findings


Uroradiology & genital male imaging

Case Type

Clinical Cases


Athina C. Tsili1, Aikaterini Lentoudi1, Maria I. Argyropoulou1 Efi Mpalasi2, Vasiliki Malamou-Mitsi2, Konstantinos Tsampoulas1

1Department of Clinical Radiology
2Department of Pathology
University Hospital of Ioannina, Greece.

University Hospital of Ioannina,Clinical Radiology,Dept. Of Radiology; Pl. Patgis 2 45332 Ioannina, Greece;

70 years, male

Area of Interest Kidney ; Imaging Technique CT
Clinical History
A 70-year-old man with a history of chronic renal failure was referred for an incidentally found non-cystic left renal mass, sonographically. CT examination revealed the presence of a heterogeneously enhancing renal tumour and retroperitoneal lymphadenopathy.
Imaging Findings
CT examination showed an expansile, left upper pole renal mass, with ill-defined margins (Figs. 1, 2, 3). The lesion was inhomogeneous, with a CT density similar to that of normal renal parenchyma on plain images (Fig. 1). A small calcification was revealed within the tumour. The mass showed moderate, heterogeneous enhancement after contrast-material administration (Fig. 2), causing amputation and erosion of the upper and middle calyces (Fig. 3). The CT findings were strongly suggestive of renal malignancy. Perinephric stranding (Figs. 2a, b) in the vicinity of the mass indicated spread of the tumoural tissue. The inferior vena cava and the left renal vein were patent. Retroperitoneal lymphadenopathy (Fig. 2c) was found to coexist, confirming the diagnosis of malignancy.
Left radical nephrectomy showed a high-grade (grade IV) unclassified renal cell carcinoma (Fig. 4), with invasion of the perinephric fat (stage pT3a).
Renal cell carcinoma (RCC) represents 1-3% of all malignancies in the adult population, representing a significant cause of morbidity and mortality [1, 2]. According to 2004 WHO classification RCC includes five main histological subtypes, that is conventional (clear cell), chromophil (papillary), chromophobe, collecting duct and unclassified category [3-5].
Unclassified renal cell carcinoma (URCC) is a category that does not fit into the other histological types of RCC, based on histological and/or genetic characteristics [6-11]. This rare variant accounts for 3-5% of RCCs [6-11]. Zisman et al. in a study of 31 URCCs reported an aggressive biologic behavior and a poor prognosis for unclassified variety of RCC [6]. More specifically, unclassified disease was associated with larger tumour size, increased risk of adrenal gland involvement, direct invasion to adjacent organs, bone, regional and nonregional lymph node metastases and sarcomatoid differentiation [6]. The median survival time for these patients was reported at 4.3 months [6]. In an analysis of 85 cases of URCCs, Karakiewich et al. reported a mortality rate 4.7 times higher than for patients with conventional RCC [7]. Crispen et al. reported that URCCs are more likely to have regional lymph node metastases, higher tumour grade, tumor necrosis and sarcomatoid differentiation when compared to clear cell RCC, although no statistically significant difference in patient outcome was noted [8]. The above characteristics were met in this case. Our patient presented with a high grade URCC and advanced stage at diagnosis.
Imaging Perspectives
Computed tomography is considered the examination of choice for the detection and staging of RCC [1, 2, 12-15]. Multidetector CT with the improvement of spatial resolution and the ability to obtain multiplanar and three-dimensional reconstructions devoid of artefacts resulted in improvement in the preoperative evaluation of RCC [1, 2, 12-15]. Tumour size, lesion contour, presence or absence of calcification and/or necrosis, mass homogeneity or heterogeneity, pattern and degree of contrast enhancement represent important imaging features, which a radiologist must consider when interpreting a CT study [12]. The presence and pattern of enhancement remains a significant predictor of diagnosis and aggressiveness of renal cell carcinoma. More specifically, a strong and heterogeneous enhancement, as seen and in this case is more likely to represent an aggressive disease, whereas peripherally enhancing lesions are more likely to represent a less aggressive behavior [12].
Differential Diagnosis List
Unclassified renal cell carcinoma
conventional RCC
transitional cell carcinoma of the pelvicaliceal system with invasion of renal parenchyma
Final Diagnosis
Unclassified renal cell carcinoma
Case information
DOI: 10.1594/EURORAD/CASE.9599
ISSN: 1563-4086