A Case of ABO Discrepancy in a Multiple Myeloma Patient Misinterpreted as a Complication of COVID-19 Vaccination

ABSTRACT

Introduction: The effect of COVID-19 infection and its vaccines onthe immune system is still a subject of much research and debate.Unusual findings due to COVID-19 infection or COVID-19 vaccination are increasingly being reported. However, caution is warrantedto rule out known entities before considering these possibilities.Aims &Objectives: We report a case of incidentally detected ABOdiscrepancy attributed to complications of COVID-19 vaccination butdiagnosed ultimately as multiple myeloma.Materials &Methods: Case Report A 52-year-old male presentedwith weakness, easy fatigability and chest pain following the seconddose of the COVID-19 vaccine. His hemoglobin fell progressivelyand he was advised blood transfusion.Result: Blood grouping revealed ABO discrepancy in forward andreverse grouping. Routine peripheral blood smear examinationshowed rouleaux formation and background blue-tinging. The patientalso had raised ESR. The patient was suspected to have a plasma celldyscrasia, which was confirmed on serum electrophoresis and thisexplained the ABO discrepancy.Conclusions: M protein in plasma cell myeloma is known to causegroup III ABO discrepancy due to rouleaux formation which can beinterpreted as pseudo-agglutination and can be a presenting feature.Though vaccine-induced blood group discrepancies have also beenreported in the literature, a detailed workup with a good interpretationof peripheral smear findings is necessary so as not to miss the primaryunderlying disease.