Spectrum of cytokeratin-positive cells in the bone marrows of colorectal carcinoma patients.

Background: Bone marrow micrometastases (BMM) is considered to be of interest as a prognostic marker in solid tumors. The use of density-gradient separated bone marrow (BM) aspirates does not allow proper morphological characterization of the cells. An alternative approach, using routinely processed clots of BM aspirates, is presented.

Materials And Methods: BM clots from 56 colorectal carcinoma patients were stained for cytokeratin (CK), p53 and Ki67 by double immunohistochemistry. Cytokeratin-positive (CK+) cells were immunohistochemically divided into three groups, viz. Group A (CK+ probably malignant epithelial cells), Group B (CK+ morphologically non-epithelial cells) and Group C (CK+ contaminating cells).

Results: Thirty-three patients (59%) had CK+ cells, of which 19 (58%) had Group A cells and 14 (42%) had Group B cells. Fourteen of the 56 patients had reactive BM, eight of these had Group A cells and 3 had Group B cells. Group B cells and Group C cells did not express p53. Group A cells were noted in 35% of patients with carcinomas of Dukes' stage C and in 41% of patients with metastatic disease.

Conclusion: Double immunohistochemical staining of routinely processed BM clot, for p53 and Ki67 along with CK allows the sub-classification of CK+ cells.