The pathology of immunoblastic proliferations. Reaction, prelymphoma, lymphoma

This report has attempted to review the pathology of immunoblastic proliferations, to indicate their similarities and differences, and hopefully to offer some guidelines in the approach to their diagnosis. Their pathology, immunology, and clinical features overlap, making it necessary to evaluate all possible parameters in reaching definite diagnoses. Methods to identify predominant B- or T-cell populations in order to distinguish the neoplasms from the reactive or prelymphomatous lesions can be readily employed using immunohistochemical techniques on either snap-frozen or paraffin-embedded sections. Flow cytometry can be employed to identify major cell populations and evaluate DNA ploidy. DNA probe techniques and cytogenetic evaluation further define the possible clonality of immunoblastic proliferations. Common sense is a basic index for the initial approach to the problem. The abnormal immune lesions present firm challenges in histological diagnosis and in dealing with the concepts of the disease. The immunoblastic sarcomas must be recognized for their status as high-grade lymphomas and separated from the benign reversible reactions and problematic, potentially fatal abnormal immune processes.