Abnormal Bone Marrow Examination Results
Abnormal Bone marrow biopsy is characterized by disruption of the marrow architecture with groups of cytologically abnormal cells. Assessment of the tissue of origin is primarily based on morphology, clinical history, and immunocytochemical staining.
The tendency of carcinoma cells to form tightly adherent clusters frequently is helpful in recognizing these neoplasms. The clumps can appear on the marrow aspirate, but the aspirate is less sensitive than the biopsy for detecting abnormal bone marrow. Tumor clumps may occur infrequently in the aspirate, often appearing only on side or feathered edges of the film, or only in the concentrate preparation. These tumor clumps must be distinguished from clumps of damaged hematopoietic cells, which commonly appear in aspirate preparations, especially the concentrate film.
The distinction between normal and abnormal bone marrow
The distinction is best accomplished by examining cells at the periphery of the clumps to determine if the cells show the morphology of hematopoietic precursors or are cytologically atypical cells; abnormal bone marrow cells. Isolated nonhematopoietic tumor cells are seen infrequently in aspirate preparations, even when tumor is obvious in the biopsy, because of the adherent nature of most nonhematopoietic tumors. Examination of multiple films may be necessary to find isolated tumor cell clumps.
Metastatic carcinoma cells can be identified by immunocytochemical staining for epithelial markers, such as cytokeratins, markers not found on hematopoietic cells. The presence of such cells in node-negative breast cancer conveys a negative prognostic risk, although full-blown metastatic disease does not always occur.
Molecular evidence suggests that tumor cells in breast cancer may disseminate with far less advanced genomic mutations than previously thought, and that the tumor cells acquire genomic aberrations typical of metastatic cells thereafter. This finding may explain the variable clinical outcome of micrometastatic disease.
Myeloma and lymphomasare more reliably detected on the biopsy preparation, where the typical aggregation pattern of abnormal bone marrow cells can be appreciated. Abnormal lymphoid aggregates should be distinguished from lymphoid aggregates found in reactive conditions or in older patients.