[Brucellosis part 2 - clinical diagnosis, treatment and a case report of the chronic form with retroperitoneal lymphadenopathy].

Brucellosis, one of the most important zoonoses worldwide, has been eliminated in many countries including the Czech Republic through veterinary control measures. It now occurs only as an imported disease. Owing to its non-specific clinical presentation, brucellosis is classified among the so-called "great imitators" and may overlap in the differential diagnosis with lymphoma, tuberculosis, or systemic inflammatory diseases. We present the case of a 44-year-old woman with imported chronic brucellosis who presented with prolonged fever of unknown origin, arthralgias, hepatosplenomegaly, and bulky retroperitoneal and supraclavicular lymphadenopathy. FDG-PET/CT findings were initially suspicious for a lymphoproliferative disorder and prompted diagnostic lymph node excision. Histopathology revealed granulomatous necrotizing lymphadenitis, and Brucella spp. serology was concurrently positive, with a subsequent fourfold rise in antibody titer. Combination antibiotic therapy according to the Ioannina regimen (doxycycline and gentamicin) was initiated; due to persistently high antibody titers and the chronic nature of the disease, doxycycline therapy was extended to a total of six months. The patient achieved complete clinical cure and was discharged from follow-up after 12 months of monitoring. The discussion section addresses the clinical forms of brucellosis including neurobrucellosis, the role of imaging modalities (particularly FDG-PET/CT) in diagnosis and treatment monitoring, characteristic findings of non-specific laboratory diagnostic tests, and current principles of antibiotic therapy. This case illustrates the value of taking a targeted travel and exposure history in patients with prolonged febrile illness of unclear etiology and underscores the importance of including brucellosis in the differential diagnosis of fever of unknown origin even in non-endemic countries. Keywords: brucellosis, zoonosis, Brucella melitensis, fever of unknown origin, retroperitoneal lymphadenopathy, FDGPET/CT, doxycycline, travel medicine.