Histological features of hypovascular or avascular renal cell carcinoma: the experience at four university hospitals.
BACKGROUND
We aimed to evaluate the pathological features of hypovascular or avascular renal cell carcinoma (RCC), by the retrospective review of the histological features that coincide with hypovascular or avascular RCC.


METHODS
Seven hundred and ninety-one patients who underwent both preoperative angiography and nephrectomy were examined. Of these patients, the 126 patients (15.9%) who showed hypovascular or avascular angiographic features were selected. Patients with hemorrhage or cyst(s), or with at least 50% necrosis or more in the tumor, and those with renal tumor metastatic to the kidney were excluded. The criteria proposed by the World Health Organization (1998) were adopted for the histological classification.


RESULTS
Papillary RCC was the most frequently observed hypovascular or avascular renal tumor (44 cases; 34.9%). The vascularity differed among the variants, i.e., some cases had a basophilic and solid variant with avascular features, while the remaining cases had wide stromal organization showing hypovascular features. The second most frequently observed hyporascular or avascular RCC was chromophobe cell carcinoma (35 cases; 27.8%). No difference in vascularity was detected between variants, except for 2 cases with sarcomatoid changes (avascular features). The third most frequently observed hypovascular or avascular RCC was cyst-associated RCC (29 cases; 23%). All of the 7 RCCs originating in a cyst showed avascular features, and the remaining 22 cystic RCCs showed hypovascular features. The remaining hypovascular or avascular RCCs were cases of clear cell carcinoma accompanied by sarcomatoid changes (8 cases; 6.3%), spindle cell carcinoma (5 cases; 4.0%), and collecting-duct carcinoma (5 cases; 4.0%).


CONCLUSIONS
Hypovascular or avascular RCC can be categorized as non-clear cell carcinoma and some clear cell carcinoma accompanied by sarcomatoid changes.
Onishi
Tetsuro
T
Department of Urology, Aoto University Hospital, Jikei University School of Medicine, Tokyo, Japan. onishi@jikei.ac.jp
Oishi
Yukihiko
Y
Goto
Hirokazu
H
Yanada
Shyuichi
S
Abe
Kazuhiro
K
D002292:Carcinoma, Renal Cell / Q000098:blood supply* / Q000473:pathology*; D006785:Hospitals, University; D006801:Humans; D007680:Kidney Neoplasms / Q000098:blood supply* / Q000473:pathology*; D007685:Kidney Tubules, Collecting / Q000098:blood supply / Q000473:pathology; D009389:Neovascularization, Pathologic / Q000473:pathology*; D009392:Nephrectomy; D011379:Prognosis; D012189:Retrospective Studies