Disguised in Plain Sight: Rash and Anemia Unmasking Hidden Lymphoma
T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) is a rare and aggressive variant of diffuse large B-cell lymphoma, accounting for approximately 1-3% of DLBCL cases worldwide. In the Philippines, its exact incidence remains unknown because subtype-specific registry data are unavailable. While THRLBCL classically presents with advanced-stage disease, it may rarely manifest as Evans syndrome (warm autoimmune hemolytic anemia with immune thrombocytopenia), with associated maculopapular rash that may mimic common infectious diseases and obscure the underlying diagnosis.
Materials and Methods/Case Presentation/Objective:
A 65-year-old Filipino male presented with dry cough, generalized weakness, and a single episode of melena. Persistent symptoms prompted an emergency department consultation, where he was diagnosed with community-acquired pneumonia and discharged on oral antibiotics.
He then developed generalized, erythematous, non-pruritic maculopapular rashes and myalgias prompting hospitalization. On admission, he was noted to have severe anemia (Hemoglobin 58 g/L) and thrombocytopenia (Platelet 65 x 109/L). Given the history of melena and profound anemia, upper gastrointestinal bleeding was initially suspected, and the patient was for packed RBC transfusion and esophagogastroduodenoscopy. However, antibody screening and crossmatching revealed incompatibility, prompting Hematology referral. On further examination, cervical lymphadenopathy and splenomegaly were noted. Workup demonstrated elevated LDH, indirect hyperbilirubinemia, positive direct antiglobulin test (anti IgG and anti C3 positive), and elevated immature platelet fraction supporting a diagnosis of warm autoimmune hemolytic anemia (AIHA) with Immune thrombocytopenia, also known as Evans Syndrome.
Whole-body PET-CT revealed extensive hypermetabolic cervical, thoracoabdominal, pelvic, and inguinal lymphadenopathy. Cervical lymph node excision biopsy was performed. The patient received supportive care, including blood transfusion, antimicrobials, a thrombopoietin receptor agonist, and dexamethasone for Evans syndrome while awaiting biopsy results. Flow cytometry demonstrated a monoclonal B-cell population, while immunohistochemistry showed CD20, MUM1, and BCL2 positivity, CD10 and Cyclin D1 negativity, and an 80% Ki-67 proliferation index, confirming THRLBCL. The patient subsequently completed six cycles of R-CHOP, with resolution of the rash after the first cycle, followed by improvement in cytopenias, edema, and fever. He was discharged in stable condition to continue lymphoma-directed therapy.
Results/Description/Main Outcome Measure(s): Evans syndrome is a rare manifestation of diffuse large B-cell lymphoma (DLBCL), while thrombocytopenia-associated rash may mimic infectious illnesses and delay diagnosis. This case highlights an unusual presentation of T-cell/histiocyte-rich large B-cell lymphoma (THRLBCL) with generalized rash, thrombocytopenia, and warm autoimmune hemolytic anemia. The diagnosis was obscured by concurrent pneumonia and the absence of classic lymphoma features until transfusion incompatibility prompted hematology referral. Further evaluation confirmed Evans syndrome with extensive nodal disease, and histopathology established THRLBCL. This case emphasizes considering an underlying lymphoproliferative malignancy in patients with persistent cytopenias and unexplained hemolysis despite an apparent infectious etiology, enabling timely diagnosis and lymphoma-directed therapy.
Conclusion(s).:
THRLBCL should be considered in patients with Evans syndrome, generalized rash, and persistent cytopenias, especially when infection fails to explain the clinical course. Transfusion incompatibility due to warm AIHA may provide a crucial clue to an underlying lymphoproliferative malignancy, enabling timely diagnosis and treatment.
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