Classification of Histologic Patterns of Pseudocapsular Invasion in Organ-Confined Renal Cell Carcinoma.
A standardized histologic definition and classification of the patterns of renal tumor pseudocapsular invasion (RTPI) in renal cell carcinoma (RCC) is not available. We classified RTPI into 2 main histologic patterns: expansive and infiltrative RTPI. Patients with organ-confined RCC and infiltrative RTPI had a greater risk of cancer-specific death and might require stricter postoperative surveillance strategies.


BACKGROUND
A standardized histologic definition and classification of patterns of renal tumor pseudocapsular invasion (RTPI) in renal cell carcinoma (RCC) is not available. The aim of the present study was to propose a classification of RTPI patterns and assess their correlation with other pathologic features and prognosis.


METHODS
The renal tumor pseudocapsule was assessed by 2 expert genitourinary pathologists on the histologic slides of 190 specimens from radical nephrectomy performed for organ-confined (pT1-pT2) RCC. The histologic patterns of RTPI were classified and described. The association between the RTPI patterns and other pathologic features was assessed. The Kaplan-Meier method was used to calculate the survival functions, and Cox regression models were used to assess the predictors of cancer-specific survival.


RESULTS
RTPI was classified into 2 main histologic patterns (expansive and infiltrative). Expansive and infiltrative RTPI was observed in 39.5% and 51.6% of cases, respectively. A significant association between the RTPI pattern and Fuhrman grade (P = .006) and RCC histologic subtype (P = .034) was detected. Patients with infiltrative pseudocapsular invasion had significantly poorer 5- and 10-year cancer-specific survival rates than patients with expansive invasion or no invasion (93.6% vs. 98.9% and 84.9% vs. 93%, respectively; P = .039). The presence of infiltrative pseudocapsular invasion was a significant predictor of cancer-specific survival (hazard ratio 4.38, 95% confidence interval 1.04-20.27).


CONCLUSIONS
An expansive and an infiltrative RTPI pattern can be described. In our study, patients with organ-confined RCC and an infiltrative RTPI pattern had a greater risk of cancer-specific death and might require stricter postoperative surveillance strategies.
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy. Electronic address: alessandro.volpe@med.uniupo.it.
Alessandro
A
Volpe
Divisions of Urology and Pathology, University of Turin, San Luigi Hospital, Orbassano, Italy.
Enrico
E
Bollito
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy.
Cristina
C
Bozzola
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy.
Antonia
A
Di Domenico
Divisions of Urology and Pathology, University of Turin, San Luigi Hospital, Orbassano, Italy.
Riccardo
R
Bertolo
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy.
Luisa
L
Zegna
Divisions of Urology and Pathology, University of Turin, San Luigi Hospital, Orbassano, Italy.
Eleonora
E
Duregon
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy.
Renzo
R
Boldorini
Divisions of Urology and Pathology, University of Turin, San Luigi Hospital, Orbassano, Italy.
Francesco
F
Porpiglia
Divisions of Urology and Pathology, Maggiore della Carità Hospital, University of Eastern Piedmont, Novara, Italy.
Carlo
C
Terrone
D000368:Aged; D002292:Carcinoma, Renal Cell / Q000145:classification / Q000401:mortality / Q000473:pathology*; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D007668:Kidney / Q000473:pathology; D007680:Kidney Neoplasms / Q000145:classification / Q000401:mortality / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D016016:Proportional Hazards Models; D012189:Retrospective Studies
Capsular invasion; Histology; Prognosis; Pseudocapsule; Renal tumor