Concurrent Brucellosis and Acute Lymphoblastic Leukemia: A Case Report

Acute lymphoblastic leukemia (ALL) is a rare hematologic malignancy that leads to significant qualitative and quantitative lymphocyte deficits. These immunological gaps predispose patients to various bacterial and opportunistic infections. Brucellosis, an intracellular infection endemic in many regions including Iran, presents with nonspecific symptoms such as prolonged fever, malaise, and organomegaly, which closely mimic the clinical manifestations of leukemia. Their co-occurrence, even in brucellosis-endemic areas, is actually rare. In addition, their similarity in clinical presentation can result in diagnostic delay or misdiagnosis.

A 47-year-old male shepherd from an endemic region in Iran presented with a 1-month history of progressive weight loss, fever (38.4°C), and muscle cramps. Initial physical examination revealed pallor and tachycardia without lymphadenopathy. Laboratory investigations showed severe leukocytosis (103 × 10³/μL) and elevated lactate dehydrogenase (1190 U/L). Although initial serological tests for brucellosis (Wright and 2-ME) were negative, bone marrow aspiration and flow cytometry confirmed B-cell ALL. Cytogenetic analysis identified the Philadelphia chromosome (t (9; 22), p210 transcript). The patient began induction chemotherapy with the hyper-CVAD regimen combined with dasatinib. Despite hematological improvement, persistent fever and diaphoresis prompted a re-evaluation for infectious etiologies. Repeated brucellosis testing yielded strongly positive results (Wright 1/320 and 2-ME 1/640), suggesting a potential prozone effect in initial tests or recent acquisition. Antibiotic therapy with rifampin and doxycycline was integrated into the oncological protocol. The patient showed rapid clinical improvement within 1 week and subsequently achieved complete remission, which was maintained throughout a 2-year follow-up.

This case highlights the importance of considering brucellosis in the differential diagnosis of febrile patients with hematologic malignancies in endemic areas. Overlapping symptoms can lead to diagnostic delays. It is crucial to repeat serological tests or use serial dilutions to circumvent the prozone effect when clinical suspicion persists in immunocompromised patients.