ACUTE TOXOPLASMOSIS IN AN IMMUNOCOMPETENT PATIENT PRESENTING WITH TRANSIENT MONOCLONAL SPIKE: A CASE REPORT

Although acute Toxoplasma gondii infection is typically asymptomatic or presents as a self-limited mononucleosis-like syndrome in immunocompetent individuals, atypical forms may mimic lymphoproliferative diseases, raising suspicion for hematologic malignancies. We report a 45-year-old previously healthy man with 14 days of low back pain and 39°C fever, followed by sweating, frontal headache, myalgia, asthenia, anorexia, and abdominal pain. On examination, he had posterior cervical and inguinal lymphadenopathy. Complete blood count showed leukocytosis with atypical lymphocytes and mild thrombocytopenia; C-reactive protein was 134 mg/L; AST 133 U/L; ALT 134 U/L; GGT 575 U/L. Chest and abdominal CT revealed lymphadenopathy in the celiac chain (1.9 × 1.2 cm) and hepatosplenomegaly. Non-oliguric acute kidney injury progressed with creatinine 2.05 mg/dL and proteinuria 1.6g/24h. Serologies for cytomegalovirus and Epstein-Barr virus were negative; toxoplasmosis serology showed IgM 20.3 IU/mL and IgG 31.5 IU/mL (reference values >0.6 and >3 IU/mL, respectively). Serum protein electrophoresis revealed an IgG-κ monoclonal spike (6.7%). Given the possibility of lymphoproliferative disease, bone marrow biopsy was considered; however, treatment for toxoplasmosis with trimethoprim-sulfamethoxazole for 21 days was initiated, with outpatient follow-up. The patient had favorable evolution: resolution of fever and systemic symptoms, regression of lymphadenopathy and splenomegaly, normalization of creatinine (0.9 mg/dL), and disappearance of proteinuria. Follow-up electrophoresis confirmed remission of the monoclonal spike. Although rarely reported, acute toxoplasmosis can present with transient monoclonal gammopathy and nephropathy, mimicking hematologic malignancies. Recognition of this presentation broadens the differential diagnosis of mono-like syndromes and avoids unnecessary invasive workup.