Connective Tissue Oncology Society

2001 CTOS Annual Meeting Posters— Pathology

TISSUE-ARRAY FOR IMMUNOHISTOCHEMICAL STUDIES IN SOFT TISSUE SARCOMA
Jacob Engellau¹, Måns Åkerman², Harald Anderson³, Henryk A Domanski², Thor A Alvegård¹, Mef C Nilbert¹
¹Dept. of Oncology, University hospital, ²Dept. of Pathology, University hospital, ³Dept. of Cancer Epidemiology, University hospital

OBJECTIVE: Malignant fibrous histiocytoma (MFH) represents a heterogenous soft tissue sarcoma entity. We have compared different methods to determine immunohistochemical (ICH) staining in whole-tissue sections, evaluated the tissue-array technique and assessed ICH heterogeneity using the proliferation marker Ki-67.

METHODS: The techniques were evaluated in 47 tumor blocks from 11 MFH. Whole-tissue sections were assessed using two reference methods (counting 400 cells along a line or counting 10 high power fields, x40). Tissue-array utilized multiple 0.6-mm tumor biopsies.

RESULTS: The whole-tissue methods gave Ki-67 expression levels of 13% and 11%, respectively and the tissue-array technique correlated well with the whole-tissue ICH with average 8.6% higher Ki-67 expression in the array-sections. ICH heterogeneity gave a median standard deviation (SD) of 2.3% witin the tumor blocks and of 2.5% between the blocks from the same tumor.

CONCLUSION: We conclude that the tissue-array method yields good quality ICH staining and expression levels for Ki-67 comparable to whole-tissue staining in MFH. Because of tumor heterogeneity several tumor blocks should ideally be studied and due to loss of biopsies in the array-process multiple biopsies should be taken. The feasibility of tissue-array offers new possibilities for ICH studies using multiple markers in large tumor series.