Abstract
In cases of hypergammaglobulinemia due to hematological malignancy, it has been reported that nonspecific reactions are often observed in test items that are affected by the antigen–antibody reactions. We here report on a case of angioimmunoblastic T-cell lymphoma (AITL) that exhibited false high levels of the fibrin/fibrinogen degradation product (FDP) and D-dimer (D-D). The patient was a woman in her 60s. She was diagnosed as having AITL on the basis of multiple lymphadenopathy, rash, and symptoms of liver and lung infiltration. On day 9 of hospitalization, the D-D level was found to be elevated, with the error message “prozone” displayed. As it appeared that the level exceeded the detection range of the device, dilution measurement was performed. As this resulted in a markedly lower level than the theoretical value, a nonspecific reaction was suspected and detailed tests were conducted. As immunoglobulin levels had increased when false high levels of FDP and D-D were detected, and dithiothreitol (DTT) processing decreased measurement values, we estimated that IgM was involved in causing the false high values. Western blotting results also suggested that the diluted measurement values were close to the true levels. As was shown for our patient, when false high levels of FDP and D-D are exhibited with no clinical hemorrhagic or thrombotic symptoms, dilution measurement could be a simple and effective method for determining whether a nonspecific reaction has occurred.
