Post transplant malignancies constitute a well-known risk for the development of malignant tumors which can adversely affect the transplant patient and may result in death. This study aims to investigate some morphologic and immunohistochemical features of a group of posttransplant malignant tumors in comparison with similar tumors developing in the usual setting.
Methods: The study group contains 40 cases of malignant tumors with suitable pathologic material found among 1350 transplant patients (1229 kidney, 113 liver, 8 heart). Tumors with 3 or more examples were compared with twice the number of randomly selected controls. These include the following: Kaposi sarcoma (n: 14), extranodal lymphoma (n: 9), squamous cell carcinoma (n: 6) and nodal lymphoma (3). The variables that were analysed in these subset of cases were the following: Degree of differentiation, predisposing lesions (when present) and the host response. For lymphomas, histological subtype, B or T lymphocyte origin and the Ki67 proliferation index were also determined.
Results: Ninety percent (36) of the tumors occurred in kidney transplant patients and 10% (4) in patients with a liver transplant. Posttransplant squamous cell carcinomas were better differentiated in comparison to controls and they have been more frequently associated with a precursor lesion. Although Kaposi sarcoma involved internal organs more frequently in posttransplant patients than controls, morphological features were similar. Ki-67 proliferation index was higher in posttransplant nodal lymphomas and lower in extranodal ones in comparison with the controls. Our findings suggest that certain posttransplant malignancies may display different characteristics than their de novo counterparts.