Brucellosis Presenting with Hemorrhagic Manifestations and Severe Thrombocytopenia: A Case Report

Background: Brucellosis is a global zoonosis, commonly presenting with mild anemia and leukopenia, while severe thrombocytopenia with hemorrhagic manifestations as the initial symptom is extremely rare and easily misdiagnosed as primary hematological diseases. Case Presentation: A 57-year-old male farmer presented with progressive fatigue, anorexia, diffuse cutaneous petechiae, oral blood blisters, hematuria, melena, and acute dyspnea. Laboratory tests showed a platelet count of 2× 10 9 /L. The white blood cell count was at the lower limit of normal (WBC 3.79× 10 9 /L), and elevated ferritin (876.9 ng/mL) was noted. Initial bone marrow aspiration suggested primary immune thrombocytopenia (ITP). The patient received intravenous immunoglobulin (IVIG) 400 mg/kg/d for 5 consecutive days and eltrombopag 50 mg/d orally for 10 days, but platelet counts remained unimproved. Subsequent blood culture identified Brucella melitensis , and Brucella agglutination test titer was > 1:400. Targeted antimicrobial therapy (doxycycline + rifampin) combined with dexamethasone 10 mg/d intravenously for 3 days, then tapered by 2 mg every 2 days until discontinuation (total course 10 days) was initiated. Platelet counts began to rise on the 6th day of antimicrobial therapy, reached 30× 10 9 /L at 5 weeks, and normalized to 90× 10 9 /L at 10 weeks. Conclusion: Initial misdiagnosis as ITP was due to overlapping clinical and laboratory features (severe thrombocytopenia, positive anti-platelet antibodies, and bone marrow megakaryocyte maturation arrest). Key diagnostic clues included epidemiological history of sheep contact and positive Brucella serology/culture. Targeted antimicrobial therapy combined with short-course corticosteroids remains the cornerstone of treatment for this rare presentation.