Effect of histopathologic characteristics on pseudocapsular invasion in the case of partial nephrectomy for renal tumours

Objective: It is aimed to define the existence of pseudocapsular structure on renal tumours, illuminate the relation between pseudocapsular invasion and Fuhrman grade histological type that are among histopathologic prognostic risk factors and determine the relation between surgical margin positivity and existence of pseudocapsular invasion. Sequential partial nephrectomy series and relevant pathological preparations were retrospectively reviewed in order to evaluate these issues.

Methods: The study includes 123 patients diagnosed with T1 renal tumour and treated with partial nephrectomy in between January 2007 and June 2016. Benign angiomyolipoma was excluded due to complete non-existence of pseudocapsule. 99 T1 patients diagnosed with renal cell cancer whose pathological slides can be duly analysed were included in the study. Clinical and pathological details were evaluated for all patients. Existence of pseudocapsule was revealed for all patients. Pseudocapsule invasion was classified by existence of expansive and infiltrative type and non-existence of pseudocapsule invasion. The groups have been assessed by their histopathologic characteristics.

Results: Compared to the group in which pseudocapsular invasion was not detected, clear-cell histological subtype was observed more frequently in a statistically significant way in the group with expansive pseudocapsular invasion and infiltrative pseudocapsular invasion respectively (p = 0.017 and p < 0.001). Pathological tumour sizes were found out to be statistically similar (p = 0.874). There was not a statistically significant difference in terms of Fuhrman grade (p = 0.220). There was not a statistically significant difference in terms of surgical positive margin (p = 0.609).

Conclusion: It was indicated in our study that only the histological subtype affected pseudocapsular invasion in group of patients treated with partial nephrectomy but tumour size, tumour stage, tumour location as well as endophytic and exophytic character did not affect invasion. It has also been revealed that surgical margin positivity is not correlated with pseudocapsular invasion.