[Q fever: bone marrow characteristic granuloma]

Area of Science:

• Infectious Diseases
• Histopathology
• Microbiology

Background:

• Q fever is a global zoonotic disease caused by Coxiella burnetii, an obligate intracellular bacterium.
• Acute Q fever symptoms include flu-like illness, pneumonia, or hepatitis.
• Chronic Q fever, particularly endocarditis, can occur in predisposed individuals and may present with negative blood cultures.

Observation:

• A distinctive "doughnut" granuloma, featuring a clear central space rimmed by inflammatory cells and eosinophilic material, is characteristic of Q fever.
• This histological pattern has been observed in liver and bone marrow biopsies of infected organs.
• The case describes a 37-year-old male patient with persistent fever.

Findings:

• Bone marrow biopsy revealed the characteristic "doughnut" granuloma.
• The presence of the granuloma strongly suggested Q fever.
• Serological tests confirmed the diagnosis of Coxiella burnetii infection.

Implications:

• The "doughnut" granuloma is a valuable diagnostic marker for Q fever, especially in cases with atypical presentations or negative routine cultures.
• Histopathological examination of bone marrow biopsies can significantly aid in early and accurate diagnosis of Q fever.
• This finding underscores the importance of considering Q fever in the differential diagnosis of unexplained persistent fever and granulomatous inflammation.