Publication date: May 01, 2026
The effect of COVID-19 infection and its vaccines on the immune system is still a subject of much research and debate. Caution is warranted to rule out known entities before considering these possibilities. We report a case of an incidentally detected ABO discrepancy initially suspected to be temporally associated with COVID-19 vaccination but diagnosed ultimately as multiple myeloma. A 52-year-old male patient presented with weakness, easy fatigability, and chest pain following the second dose of the COVID-19 vaccine. His hemoglobin fell progressively, and he was advised blood transfusion. Blood grouping revealed an ABO discrepancy in forward and reverse grouping. The initial indirect Coombs test (ICT) showed 3+ reactivity, possibly due to non-specific interference from elevated serum proteins, but the repeat test was negative. Routine peripheral blood smear examination showed rouleaux formation and background blue-tinging. Saline replacement dispersed the RBC aggregates, confirming pseudo-agglutination. The patient also had a raised erythrocyte sedimentation rate (ESR). The patient was suspected of having a plasma cell dyscrasia, which was confirmed on serum electrophoresis, and this explained the ABO discrepancy. M protein in plasma cell myeloma is known to cause group III ABO discrepancy due to rouleaux formation, which can be interpreted as pseudo-agglutination and can be a presenting feature. Though temporal association with vaccination may raise suspicion, a detailed work-up is necessary to avoid misattribution and missing underlying disease.
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| Concepts | Keywords |
|---|---|
| Covid | abo blood group |
| Misattribution | abo discrepancy |
| Myeloma | coomb’s test |
| Vaccine | covid 19 vaccination |
| plasma cell myeloma |
Semantics
| Type | Source | Name |
|---|---|---|
| disease | MESH | Multiple Myeloma |
| disease | MESH | COVID-19 |
| disease | MESH | infection |
| pathway | REACTOME | Immune System |
| disease | MESH | chest pain |
| disease | MESH | plasma cell dyscrasia |
| pathway | REACTOME | Reproduction |
| drug | DRUGBANK | Coenzyme M |
| disease | MESH | Allergy |
| disease | MESH | autoimmune diseases |
| disease | MESH | syndrome |
| disease | MESH | macroglobulinemia |
| disease | MESH | Hodgkin’s lymphoma |
| disease | MESH | anemia |
| disease | MESH | macrocytic anemia |
| disease | MESH | leukopenia |
| disease | MESH | thrombocytopenia |
| drug | DRUGBANK | Albendazole |
| disease | MESH | hypercalcemia |
| disease | MESH | renal failure |
| disease | MESH | fever |
| disease | MESH | pain |
| disease | MESH | fatigue |
| disease | MESH | myocarditis |
| disease | MESH | hematologic malignancies |
| disease | MESH | back pain |
| disease | MESH | viral infections |
| disease | MESH | autoimmune hemolytic anemia |
| disease | MESH | hemolysis |
| disease | MESH | reticulocytosis |
| disease | MESH | bone disease |
| disease | MESH | immune thrombocytopenia |
| disease | MESH | severe acute respiratory syndrome |
| disease | MESH | coronavirus infection |