Lymph node metastasis is the most important predictor of prognosis, after surgery, in colorectal carcinoma. The term “micrometastasis” has evolved from a morphological definition to one that is used with molecular‐based techniques. We review the literature to evaluate the significance of detecting micrometastases in colorectal carcinoma, either by morphological or molecular techniques, and address technical difficulties encountered with both. Routine use of immunohistochemistry is not recommended as most studies show little change in staging or prognosis. Radioimmunoguided surgery may prove beneficial, but problems of false positives in benign diseases need to be addressed. Immunohistochemical detection of micrometastatic deposits in bone marrow aspirates holds the most promise for clinical practice. Molecular techniques are more sensitive than immunohistochemistry, but prognostic value needs to be determined. Molecular diagnostics can also determine genetic alterations and mutations that should improve our understanding of metastatic colon cancer and staging accuracy. J. Surg. Oncol. 1998;67:194–202. © 1998 Wiley‐Liss, Inc.

The CD45 family contains protein tyrosine phosphatase (PTPase) activity and is expressed in one or more of its isoforms on all lymphohematopoietic cells. Considerable work has focused on CD45 expression by lymphoid cells, but minimal work has involved granulocytes. Granulocytic, or myeloid, cell differentiation is accompanied by a number of morphologic and immunophenotypic changes. This study used flow cytometric and immunocytochemical methods in conjunction with morphologic assessment to investigate the expression of CD45 isoforms during differentiation of normal and malignant granulocytic cells. On normal bone marrow cells, the quantity of surface CD45 did not change during earlier stages but did increase significantly at the terminal stages (bands and polymorphonuclear leukocytes [PMNs]). CD45RO (the low relative molecular mass [Mr] isoform) was very dimly expressed on immature cells but became increasingly brighter beginning at approximately the myelocyte stage. The high Mr isoform (CD45RA) was virtually absent from the cell surface at all stages. Only a small percentage (3-15%) of PMNs expressed surface CD45RA. However, there was a cytoplasmic pool of each isoform associated with membrane-bound granules found throughout differentiation, with remarkable increases in expression at the terminal stages. In the case of acute myeloid leukemias (AMLs), most cases expressed surface CD45RA with, or without, CD45RO, regardless of their French-American-British (FAB) classification. This appeared to be a stable process at diagnosis and relapse in individual patients and may therefore serve as a diagnostic aid. The biologic significance of this aberrant expression of CD45RA by malignant cells is unknown but raises important questions regarding the cellular processes of phosphorylation/dephosphorylation in normal and malignant cells.

After several transfusions with D-negative blood, an O Rh-negative women was apparently sensitized to the C and D antigens. In her prenatal workup, it became evident that she had in fact not been sensitized to D but to G, which initially appeared as anti-D plus anti-C. This sensitization pattern is an unusual occurrence in itself. Moreover, the fetus was affected significantly and was delivered at 32 1/2 weeks with moderate hemolytic disease of the newborn. Consideration is given to points regarding current methods of screening Rh-negative women for transfusion, the use of anti-Rh immune globulin in patients sensitized to anti-C and anti-G, medicolegal implications, and continuous attention to the risk-benefit ratio in decisions to use transfusions.