Chronic Splenic Brucellosis: CT Diagnosis, Imaging Interpretation, Pathophysiology, and AI-Assisted Clinical Decision Making
Clinical Hook
Imagine evaluating an 84-year-old man who arrives at the emergency department with fever, shortness of breath, and newly developed confusion. At first glance, these symptoms suggest pneumonia, sepsis, or even stroke. Physical examination reveals no remarkable findings, and there is no obvious source of infection.
Then an abdominal contrast-enhanced CT unexpectedly reveals a coarsely calcified lesion within the spleen.
Most clinicians would initially consider healed granulomatous disease, old trauma, splenic infarction, or calcified neoplasm. Few would immediately suspect brucellosis, especially in a patient whose occupational exposure occurred more than five decades earlier.
However, blood cultures ultimately identify Brucella suis, confirming reactivation of chronic splenic brucellosis. This remarkable case demonstrates that zoonotic infections can persist silently for decades before becoming clinically apparent.
For radiologists, infectious disease specialists, and AI-assisted diagnostic systems alike, recognizing this imaging pattern is essential because delayed diagnosis can lead to prolonged bacteremia, recurrent infection, and potentially life-threatening complications.
Learning Objectives
After reading this article, readers will be able to:
- Understand the anatomy and immunological role of the spleen in chronic infection.
- Explain the pathophysiology of chronic splenic brucellosis and disease reactivation.
- Interpret characteristic CT findings of calcified splenic brucellosis from a radiologist's perspective.
- Differentiate chronic splenic brucellosis from other calcified splenic lesions.
- Appreciate how artificial intelligence can assist—but not replace—expert radiological interpretation.
- Apply imaging findings to multidisciplinary clinical decision-making.
1. Anatomy Review
The spleen is the largest lymphoid organ in the human body and plays an indispensable role in immune surveillance, blood filtration, and removal of senescent erythrocytes. Anatomically, it is located in the left upper quadrant beneath the diaphragm and receives its blood supply through the splenic artery, one of the major branches of the celiac trunk.
The splenic parenchyma is composed of two major compartments:
- White pulp, responsible for adaptive immune responses through lymphocyte activation.
- Red pulp, which filters microorganisms and damaged erythrocytes from the bloodstream.
Because blood flow through the spleen is slow and highly exposed to macrophages, blood-borne pathogens such as Brucella species can survive intracellularly for prolonged periods. Chronic infection may eventually induce granulomatous inflammation, fibrosis, dystrophic calcification, and persistent bacterial reservoirs.
This unique immunological microenvironment explains why the spleen frequently becomes involved during chronic systemic infections.
Figure 1. Normal Splenic Anatomy
Figure Legend
Illustration demonstrating the normal anatomy of the spleen, including the splenic artery, splenic vein, red pulp, white pulp, trabecular framework, and adjacent abdominal organs. Understanding normal splenic anatomy is essential for interpreting focal calcified lesions and distinguishing chronic infectious processes from neoplastic disease.
2. Case Presentation
History
An 84-year-old man presented with:
- Fever
- Dyspnea
- Newly developed confusion
Physical examination was largely unremarkable despite systemic symptoms. Review of his occupational history revealed that during his late twenties he worked in a slaughterhouse processing pigs, where he experienced recurrent self-limited febrile illnesses accompanied by night sweats and a 23-kg weight loss. These historical features later proved to be highly relevant to the final diagnosis.
Symptoms
The patient demonstrated constitutional symptoms commonly associated with chronic systemic infection:
- Fever
- Dyspnea
- Confusion
- Previous night sweats
- Significant historical weight loss
Unlike acute bacterial sepsis, no localized abdominal symptoms were initially emphasized in the source case.
Physical Examination
The source document reports no remarkable physical findings despite the patient's systemic symptoms, highlighting the often subtle clinical presentation of chronic brucellosis.
Clinical Question
What explains the presence of a densely calcified splenic lesion in an elderly patient with constitutional symptoms and positive blood cultures?
Laboratory Findings
The decisive laboratory finding was:
- Positive blood cultures for Brucella suis
This microbiological confirmation, together with the patient's remote occupational exposure and imaging findings, supported the diagnosis of chronic splenic brucellosis.
CT Findings
Figure 2. Axial C+
Contrast-enhanced CT of the abdomen demonstrated a coarsely calcified, well-defined splenic lesion measuring approximately 4.3 × 4.1 × 2.6 cm. The imaging appearance was interpreted in the source material as being compatible with chronic splenic brucellosis in the context of the clinical and microbiological findings.
Pathology
Although histopathological images are not provided in the uploaded document, the imaging appearance suggests chronic granulomatous inflammation with fibrosis and dystrophic calcification, consistent with longstanding infection. This interpretation is inferential and extends beyond the source document.
Final Diagnosis
Chronic Splenic Brucellosis (Reactivation) caused by Brucella suis, supported by the patient's occupational history, characteristic calcified splenic lesion on CT, and positive blood cultures.
3. Pathophysiology
Brucella species are facultative intracellular Gram-negative coccobacilli that survive within macrophages by evading lysosomal destruction. This intracellular lifestyle enables prolonged persistence within the reticuloendothelial system, particularly the spleen, liver, bone marrow, and lymph nodes.
In chronic infection, persistent immune activation promotes granuloma formation, progressive fibrosis, and dystrophic calcification. These pathological changes explain the characteristic appearance of coarse splenic calcification on CT imaging in longstanding disease.
In the present case, the patient's occupational exposure to infected swine decades earlier likely established latent infection. Reactivation later in life may have been facilitated by immunosenescence associated with advanced age, allowing dormant bacteria to proliferate and produce systemic symptoms once again. While the uploaded case states that reactivation was suspected, the precise biological trigger was not established.
Figure 3. Pathophysiology of Chronic Splenic Brucellosis
Figure Legend
Diagram illustrating the proposed progression from zoonotic exposure to intracellular persistence of Brucella, chronic granulomatous inflammation, fibrosis, dystrophic calcification, and eventual clinical reactivation in the spleen.
4. Epidemiology
Table 1. Epidemiology of Chronic Splenic Brucellosis
| Parameter | Summary |
|---|---|
| Etiologic organism | Brucella species (B. melitensis, B. suis, B. abortus, B. canis) |
| Transmission | Contact with infected livestock, slaughterhouse exposure, unpasteurized dairy products |
| Age | Any age; occupational exposure is common in working adults |
| Sex | More common in males due to occupational exposure |
| Major risk factors | Farming, veterinary work, slaughterhouse employment, laboratory exposure |
| Geographic distribution | Mediterranean region, Middle East, Latin America, parts of Asia and Africa |
| Splenic involvement | Common in systemic disease; chronic calcified lesions are uncommon |
The uploaded case emphasizes occupational exposure to pigs in a slaughterhouse decades before clinical reactivation, illustrating the long latent course that chronic brucellosis may exhibit in selected patients.
5. Clinical Presentation
Chronic splenic brucellosis is one of the most challenging manifestations of human brucellosis because its presentation is often nonspecific, intermittent, and capable of mimicking malignancy, tuberculosis, fungal infection, or other chronic inflammatory diseases. In many patients, constitutional symptoms fluctuate over months or years, delaying diagnosis until imaging or microbiological confirmation reveals the underlying infection.
In the uploaded case, the patient presented with fever, dyspnea, and newly developed confusion, while physical examination was largely unremarkable. His remote occupational exposure to pigs and previous history of recurrent febrile illness with profound weight loss became critical clues only after imaging and blood culture findings were reviewed together.
Typical manifestations of chronic brucellosis include:
- Persistent or intermittent fever
- Night sweats
- Fatigue
- Weight loss
- Malaise
- Arthralgia
- Myalgia
Splenic involvement may remain clinically silent until the lesion becomes sufficiently large or is discovered incidentally during abdominal imaging.
Neurological Manifestations
Although the uploaded case reports new-onset confusion, it does not establish direct neurobrucellosis. In elderly patients, altered mental status may result from systemic infection, metabolic disturbance, or sepsis-associated encephalopathy. Therefore, correlation with neurological imaging and cerebrospinal fluid analysis would be required if central nervous system involvement were suspected. The source document does not provide these investigations.
Laboratory Findings
The uploaded case identifies the following key laboratory result:
- Positive blood culture for Brucella suis
No additional inflammatory markers, liver function tests, or hematologic indices are provided in the source document.
Clinical Red Flags
Radiologists and clinicians should consider chronic brucellosis when the following features coexist:
- History of livestock or slaughterhouse exposure
- Consumption of unpasteurized dairy products
- Persistent constitutional symptoms
- Calcified splenic lesion
- Positive blood cultures for Brucella
- Previous unexplained recurrent febrile episodes
6. Imaging Features
This section represents the core diagnostic value of the case because imaging provided the first objective evidence suggesting chronic splenic pathology before microbiological confirmation.
Figure 2. Axial C+
Figure Legend
Figure 2. Contrast-enhanced axial CT demonstrates a well-circumscribed, densely and coarsely calcified splenic lesion measuring approximately 4.3 × 4.1 × 2.6 cm. In the clinical context of positive Brucella suis blood cultures and prior occupational exposure, the imaging appearance is consistent with chronic splenic brucellosis. The dense calcification reflects longstanding granulomatous inflammation and chronic tissue remodeling rather than acute infection.
Interpretation
Examination
Contrast-enhanced CT of the abdomen and pelvis.
Technique
Axial contrast-enhanced CT images of the upper abdomen.
Lesion Location
- Splenic parenchyma
Size
- Approximately 4.3 × 4.1 × 2.6 cm
Shape
- Rounded
- Well-defined
Margin
- Smoothly circumscribed
Internal Characteristics
- Dense coarse calcification
Enhancement
The source figure primarily emphasizes calcification. Enhancement characteristics of the lesion itself are not described in the uploaded case.
Hemorrhage
Not reported.
Necrosis
Not reported.
Perisplenic Fluid
Not demonstrated in this first case.
Adjacent Organ Invasion
No evidence is described.
Why Does This CT Appearance Occur?
The imaging appearance reflects the biological evolution of chronic infection.
Following hematogenous dissemination, Brucella organisms persist intracellularly within macrophages. Continuous immune activation promotes granulomatous inflammation, fibrosis, and eventually dystrophic calcification. Unlike acute splenic abscesses, which often appear as low-attenuation lesions with peripheral enhancement, chronic brucellosis may become almost completely calcified.
Therefore, the calcification itself represents the cumulative consequence of decades of host-pathogen interaction rather than active mineral deposition by bacteria.
Clinical Imaging Interpretation
The CT findings have several important clinical implications.
1. Chronicity
Dense calcification strongly suggests a longstanding disease process rather than acute infection.
2. Previous Granulomatous Inflammation
The lesion likely represents healed or partially healed granulomatous infection.
3. Reactivation
Despite extensive calcification, viable organisms may persist within fibrotic tissue, explaining recurrent bacteremia in this patient.
4. Importance of Clinical History
Without knowledge of previous slaughterhouse exposure, the imaging appearance could easily be mistaken for:
- healed tuberculosis
- fungal infection
- splenic infarction
- old hematoma
- calcified hemangioma
The diagnosis therefore depends on integrating imaging with microbiological and occupational history.
Diagnostic Imaging Pearls
Radiologists should carefully evaluate:
✓ Pattern of calcification
✓ Number of lesions
✓ Presence of splenomegaly
✓ Associated hepatic lesions
✓ Regional lymphadenopathy
✓ Signs of active inflammation
✓ Clinical exposure history
Common Pitfalls
Do not assume every calcified splenic lesion represents an old healed process.
Persistent constitutional symptoms combined with positive blood cultures should prompt consideration of chronic infectious reactivation, even when imaging appears "inactive."
Figure 4. Axial C+
Figure Legend
Figure 4. Contrast-enhanced CT demonstrates a large subcapsular splenic hematoma with associated perisplenic and perihepatic free fluid in the additional illustrative case of spontaneous splenic rupture associated with acute brucellosis. This image highlights a rare but potentially life-threatening complication requiring prompt recognition and treatment.
Reading Report
Findings
Contrast-enhanced CT demonstrates a well-defined coarsely calcified lesion within the spleen measuring approximately 4.3 cm. No imaging evidence of surrounding inflammatory change or adjacent organ invasion is described in the uploaded case. Blood cultures subsequently confirmed Brucella suis infection.
Impression
- Coarsely calcified splenic lesion consistent with chronic granulomatous disease.
- In conjunction with positive Brucella suis blood cultures and occupational exposure history, findings support chronic splenic brucellosis with suspected reactivation.
- Correlation with infectious disease consultation and prolonged antimicrobial therapy is recommended.
Clinical Correlation
This case illustrates that imaging alone cannot establish the diagnosis of chronic brucellosis. Instead, diagnostic confidence arises from integrating:
- Imaging findings
- Occupational exposure history
- Positive blood cultures
- Clinical symptoms
- Therapeutic response
The source document reports clinical improvement after combination antimicrobial therapy with doxycycline, rifampin, and trimethoprim-sulfamethoxazole, supporting the final diagnosis.
Multimodal Imaging Comparison
| Imaging Modality | Advantages | Limitations | Clinical Value |
|---|---|---|---|
| CT | Excellent detection of calcification | Limited soft-tissue characterization | First-line evaluation of calcified splenic lesions |
| MRI | Superior soft-tissue contrast | MRI findings not provided in the uploaded case | Useful if CT findings are indeterminate |
| Ultrasound | Portable and inexpensive | Operator dependent | Initial assessment of splenomegaly or focal lesions |
| Contrast-enhanced CT | Demonstrates lesion morphology and complications | Ionizing radiation | Best modality in the presented case |
| Nuclear Medicine | Functional assessment | Not included in the source | Not evaluated in this case |
Imaging Differential Diagnosis
| Disease | CT Findings | MRI Findings | Distinguishing Features |
|---|---|---|---|
| Chronic splenic brucellosis | Dense coarse calcification | Not available in source | Positive Brucella culture; exposure history |
| Tuberculous granuloma | Calcified granulomas | Variable | Pulmonary or systemic tuberculosis history |
| Histoplasmosis | Multiple calcified lesions | Variable | Endemic fungal exposure |
| Splenic infarction | Wedge-shaped defects; chronic calcification possible | Variable | Vascular etiology |
| Calcified hemangioma | Focal calcification | Characteristic enhancement on MRI | Benign vascular lesion |
The differential diagnoses above are provided as expert interpretive context and extend beyond the uploaded case report.
AI-Assisted Imaging Interpretation
A foundation imaging model analyzing this CT study would likely identify:
- Abnormal splenic morphology
- High-density calcified lesion
- Organ localization
- Lesion segmentation
- Volumetric measurements
Potential radiomic features include:
- High attenuation
- Texture heterogeneity
- Shape regularity
- Calcification density
- Lesion compactness
However, AI alone cannot infer the patient's decades-old occupational exposure or microbiological history. Without these contextual data, an AI system may classify the lesion as a nonspecific calcified granuloma rather than chronic splenic brucellosis.
This case underscores that optimal diagnosis depends on collaboration between advanced imaging AI and experienced radiologists who integrate imaging findings with clinical history, laboratory confirmation, and epidemiological risk factors.
10. Differential Diagnosis
The diagnosis of chronic splenic brucellosis is particularly challenging because its imaging appearance overlaps with several infectious, inflammatory, vascular, and neoplastic diseases. In the present case, the coarsely calcified splenic lesion initially represents a nonspecific radiologic finding. Only after integrating the patient's occupational history and positive Brucella suis blood culture does the diagnosis become highly convincing.
Unlike acute splenic abscesses, chronic splenic brucellosis often reflects decades of granulomatous inflammation, fibrosis, and dystrophic calcification. Therefore, radiologists should avoid interpreting dense splenic calcification as merely an incidental healed lesion in patients with systemic symptoms.
Table 2. Differential Diagnosis of Calcified Splenic Lesions
| Disease | CT Findings | MRI Findings* | Pathology | Key Imaging Clues |
|---|---|---|---|---|
| Chronic Splenic Brucellosis | Coarse or dense calcified lesion | Not available in the uploaded case | Chronic granulomatous inflammation | Positive Brucella culture, livestock exposure |
| Tuberculous Granuloma | Multiple calcified granulomas | Variable | Caseating granuloma | Pulmonary TB or previous tuberculosis |
| Histoplasmosis | Diffuse punctate calcifications | Variable | Fungal granulomas | Endemic fungal exposure |
| Splenic Infarction | Wedge-shaped low attenuation, chronic calcification possible | Restricted perfusion | Ischemic necrosis | Vascular disease |
| Chronic Splenic Abscess | Thick wall ± calcification | Fluid cavity | Persistent infection | Fever, leukocytosis |
| Calcified Hemangioma | Focal calcification | Characteristic enhancement | Benign vascular lesion | Enhancement pattern |
| Hydatid Disease | Rim calcification | Daughter cysts | Parasitic cyst | Epidemiologic exposure |
| Splenic Lymphoma | Splenomegaly, masses | Variable | Malignant lymphoid proliferation | FDG-PET uptake |
*The uploaded source does not provide MRI findings; MRI features listed for comparator diseases represent general radiologic knowledge rather than source-derived information.
Diagnostic Approach
For radiologists, the diagnostic sequence should include:
- Confirm lesion localization within the splenic parenchyma.
- Characterize the calcification pattern.
- Evaluate for splenomegaly and additional abdominal lesions.
- Review occupational and travel history.
- Correlate with microbiological testing.
- Consider zoonotic infection even when exposure occurred decades earlier.
This structured approach minimizes diagnostic delay in rare chronic infections.
11. Treatment Strategy
The uploaded case reports successful treatment using a multidrug antimicrobial regimen consisting of:
- Doxycycline
- Rifampin
- Trimethoprim–Sulfamethoxazole (TMP-SMX)
The patient demonstrated clinical improvement after approximately 10 days of therapy. Because the treating physicians suspected reactivation of previous brucellosis, lifelong suppressive doxycycline therapy was planned to reduce the risk of recurrence.
Conservative Management
Most patients without splenic rupture or uncontrolled abscess formation can initially be managed medically. Careful clinical monitoring is essential because chronic brucellosis may relapse even after prolonged antibiotic therapy.
Surgical Treatment
The uploaded case did not require splenectomy.
However, surgery may become necessary in selected patients with:
- Persistent abscess despite antibiotics
- Splenic rupture
- Massive hemorrhage
- Failure of medical therapy
These indications are not discussed in the uploaded document and are included here as general clinical context.
Image-Guided Intervention
No percutaneous drainage or interventional radiology procedures were performed in the uploaded case.
Rare Complication Highlight
The second illustrative case in the uploaded document describes spontaneous splenic rupture, demonstrated by a large subcapsular hematoma and free intraperitoneal fluid on contrast-enhanced CT. This emphasizes that although uncommon, acute abdominal emergencies may occur in brucellosis and require prompt recognition.
AI-Supported Treatment Planning
Future clinical AI systems may assist by:
- Predicting relapse risk.
- Monitoring treatment response longitudinally.
- Integrating imaging with microbiology.
- Recommending follow-up intervals.
- Identifying patients requiring infectious disease consultation.
Such applications remain investigational and are not described in the uploaded source.
12. Prognosis
The uploaded case demonstrates a favorable short-term clinical outcome following combination antimicrobial therapy. The patient improved clinically within ten days, but because clinicians suspected reactivation of latent infection, lifelong suppressive antimicrobial therapy was planned.
Factors Associated with Favorable Outcome
- Early microbiological confirmation
- Appropriate multidrug antibiotic therapy
- Recognition of occupational exposure
- Accurate CT interpretation
Factors Increasing Recurrence Risk
Potential contributors include:
- Persistent intracellular organisms
- Delayed diagnosis
- Incomplete antimicrobial therapy
- Immunosenescence in elderly patients
The uploaded case specifically supports suspected reactivation but does not identify the precise biological mechanism responsible for recurrence.
Imaging Follow-up
The uploaded document does not describe interval CT follow-up.
Reasonable imaging objectives during surveillance may include:
- Stability of calcified lesion
- Absence of enlarging abscess
- No new splenic lesions
- Resolution of inflammatory complications
These follow-up recommendations represent expert clinical practice rather than source-derived guidance.
13. Artificial Intelligence Perspective
Artificial intelligence has the potential to improve recognition of rare infectious diseases by integrating imaging, laboratory, and clinical information. Nevertheless, this case illustrates why AI alone remains insufficient for definitive diagnosis.
Radiomics
Potential radiomic biomarkers include:
- Lesion attenuation
- Texture heterogeneity
- Shape complexity
- Calcification density
- Edge sharpness
- Three-dimensional lesion volume
These quantitative features may improve automated characterization of chronic granulomatous disease.
Foundation Models
Large medical foundation models trained on millions of CT examinations may detect:
- Splenic abnormalities
- Organ segmentation
- Calcified lesions
- Associated abdominal pathology
However, lesion detection is fundamentally different from disease diagnosis.
Vision-Language Models (VLMs)
Future multimodal AI systems could combine:
- CT images
- Radiology reports
- Laboratory data
- Blood culture results
- Occupational history
- Epidemiological exposure
to generate clinically meaningful differential diagnoses.
Clinical Decision Support
AI-assisted decision support systems may automatically recommend:
- Blood cultures when unexplained splenic calcification accompanies fever.
- Infectious disease consultation.
- Serologic testing for zoonotic infections.
- Longitudinal imaging surveillance.
Enterprise AI Workflow
PACS Integration
AI may function directly within the PACS environment by:
- Flagging unusual splenic lesions.
- Comparing previous CT examinations.
- Measuring lesion volume automatically.
- Prioritizing suspicious studies for radiologist review.
HL7 and FHIR Connectivity
Future interoperability standards could enable seamless integration of:
- Imaging archives
- Microbiology laboratories
- Electronic health records
- Clinical AI engines
allowing imaging findings to be interpreted within their full clinical context.
Limitations of AI
This case clearly demonstrates several important limitations.
AI cannot directly infer:
- Occupational exposure that occurred decades earlier.
- Consumption of contaminated food.
- Detailed epidemiologic history.
- Clinical reasoning behind suspected reactivation.
- The significance of historical symptoms unless documented in structured records.
Accordingly, expert radiologists remain indispensable for synthesizing imaging findings with microbiological, epidemiological, and clinical information.
14. Future of Precision Medicine
Chronic infectious diseases such as brucellosis illustrate how precision medicine extends beyond genomics to include imaging, microbiology, epidemiology, and longitudinal clinical data.
Future developments may include:
Radiogenomics
Although no radiogenomic analysis is presented in the uploaded case, future research may explore associations between imaging phenotypes and host immune responses.
Digital Twin
Patient-specific computational models could simulate:
- Disease progression
- Antibiotic response
- Relapse probability
- Organ-specific complications
to support individualized treatment planning.
Federated Learning
Because chronic splenic brucellosis is uncommon, multicenter federated learning could enable collaborative AI development without sharing patient-identifiable data.
Synthetic Data
Synthetic CT datasets representing rare infectious diseases may enhance AI training while protecting patient privacy.
Precision Imaging
Future precision imaging may combine:
- CT
- MRI
- PET/CT
- Radiomics
- Laboratory biomarkers
- Genomic information
to produce personalized diagnostic pathways.
Multimodal AI
The next generation of clinical AI is likely to integrate:
- Imaging
- Pathology
- Laboratory medicine
- Electronic health records
- Clinical notes
- Epidemiological data
into a unified diagnostic platform that augments—not replaces—expert clinical judgment.
15. Clinical Pearls
The following clinical pearls summarize the most important lessons derived from the uploaded case, supplemented only where explicitly noted.
1. Chronic brucellosis should remain in the differential diagnosis of elderly patients presenting with fever of unknown origin and unexplained splenic calcification.
2. A detailed occupational history may reveal exposure that occurred decades before the current illness, as illustrated by the patient's previous slaughterhouse work with pigs.
3. Positive blood cultures for Brucella suis are essential for confirming the diagnosis in this case.
4. Coarse splenic calcification should not automatically be dismissed as an inactive healed lesion.
5. CT is highly effective for demonstrating dystrophic calcification within chronic splenic lesions.
6. Imaging findings should always be interpreted together with microbiological and epidemiological data.
7. The absence of striking physical examination findings does not exclude chronic systemic infection.
8. Reactivation of latent brucellosis remains possible even after many decades, as suspected in the uploaded case.
9. Combination antimicrobial therapy remains the cornerstone of treatment.
10. Radiologists play a critical role in identifying imaging patterns that trigger microbiological investigation.
11. Artificial intelligence can detect abnormal splenic morphology but cannot independently reconstruct decades-old exposure history.
12. Rare complications such as spontaneous splenic rupture require immediate recognition on emergency CT.
Quiz
1. Which imaging finding is most characteristic of the chronic splenic lesion described in the uploaded case?
① Multiple hepatic cysts
② Diffuse hepatic steatosis
③ Coarsely calcified splenic lesion
④ Splenic infarction without calcification
⑤ Massive splenic hemorrhage
Answer: ③ Explanation: The uploaded case describes a coarsely calcified splenic lesion measuring approximately 4.3 × 4.1 × 2.6 cm, ultimately diagnosed as chronic splenic brucellosis following positive Brucella suis blood cultures.
2. Which laboratory result established the diagnosis in this patient?
① Positive CMV PCR
② Positive EBV serology
③ Positive blood culture for Brucella suis
④ Positive tuberculosis culture
⑤ Positive fungal culture
Answer: ③ Explanation: Blood cultures were positive for Brucella suis, confirming chronic splenic brucellosis.
3. Which historical feature was most helpful in reaching the diagnosis?
① Recent international travel
② Previous abdominal trauma
③ Long-term corticosteroid use
④ Previous slaughterhouse employment involving pigs
⑤ Chronic hepatitis
Answer: ④ Explanation: The patient's remote occupational exposure to pigs became a crucial diagnostic clue after CT imaging and microbiological confirmation.
4. According to the uploaded case, which antimicrobial regimen was administered?
① Vancomycin alone
② Piperacillin-tazobactam
③ Meropenem
④ Doxycycline, rifampin, and trimethoprim-sulfamethoxazole
⑤ Ceftriaxone alone
Answer: ④ Explanation: The patient improved after combination therapy with doxycycline, rifampin, and TMP-SMX.
5. Which rare complication is illustrated in the additional case included in the uploaded document?
① Hepatic rupture
② Pancreatic necrosis
③ Spontaneous splenic rupture
④ Portal vein thrombosis
⑤ Acute appendicitis
Answer: ③ Explanation: The second illustrative case demonstrates spontaneous splenic rupture with a large subcapsular hematoma on contrast-enhanced CT.
17. Frequently Asked Questions (FAQ)
Q1. What is chronic splenic brucellosis?
It is a chronic infection of the spleen caused by Brucella species. In the uploaded case, the diagnosis was supported by CT findings and positive blood cultures for Brucella suis.
Q2. Why is the spleen commonly involved?
The uploaded document explains that the spleen plays an important role in immune function, making it susceptible to chronic infection.
Q3. What CT finding is emphasized in this case?
A densely calcified splenic lesion.
Q4. Can brucellosis reactivate decades later?
The treating physicians suspected reactivation in this patient; however, the precise biological mechanism was not established in the uploaded document.
Q5. Is MRI discussed in the uploaded case?
No. The uploaded document does not provide MRI findings.
Q6. What organism caused infection?
Brucella suis.
Q7. How was the patient treated?
Combination antimicrobial therapy consisting of doxycycline, rifampin, and trimethoprim-sulfamethoxazole.
Q8. Is splenic rupture common?
No. The uploaded document specifically presents spontaneous splenic rupture as a rare complication in a separate illustrative case.
Q9. Can AI diagnose chronic brucellosis independently?
No. AI may detect imaging abnormalities, but diagnosis requires correlation with microbiology and clinical history.
Q10. What is the key teaching point?
A calcified splenic lesion combined with compatible epidemiological history should prompt consideration of chronic brucellosis.
Conclusion
This case demonstrates how a seemingly inactive calcified splenic lesion can represent persistent zoonotic infection rather than a benign historical finding. Contrast-enhanced CT served as the pivotal imaging modality by revealing a characteristic calcified splenic abnormality, while microbiological confirmation with Brucella suis blood cultures established the diagnosis.
From a radiologist's perspective, the greatest lesson is that imaging should never be interpreted in isolation. Careful integration of occupational history, microbiological data, and imaging characteristics transformed an otherwise nonspecific calcified lesion into the diagnosis of chronic splenic brucellosis.
As artificial intelligence becomes increasingly integrated into radiology workflows, it will improve lesion detection, segmentation, and quantitative analysis. Nevertheless, this case reinforces that expert clinical reasoning remains indispensable. AI can identify the lesion; experienced physicians determine its meaning.
References
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[2] A. Marrón, J. M. Sáez, J. M. de la Torre, et al., “Current Understanding and Management of Chronic Hepatosplenic Suppurative Brucellosis,” Clinical Infectious Diseases, vol. 32, no. 7, pp. 1024–1033, 2001. doi: 10.1086/319608 Available: https://doi.org/10.1086/319608
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[4] U. S. Torres, L. V. Cardoso, and G. D’Ippolito, “A Pathognomonic Calcification Pattern in Chronic Splenic Brucellosis,” Brazilian Journal of Infectious Diseases, vol. 19, no. 6, pp. 664–665, 2015. doi: 10.1016/j.bjid.2015.06.003 Available: https://doi.org/10.1016/j.bjid.2015.06.003
[5] G. F. MacDonald, W. J. Martin, W. E. Wellman, and L. A. Weed, “Chronic Localized Brucellosis of the Spleen,” Postgraduate Medicine, vol. 40, no. 6, pp. 703–707, 1966. doi: 10.1080/00325481.1966.11696064 Available: https://doi.org/10.1080/00325481.1966.11696064
[6] N. A. Al-Nakshabandi, “The Spectrum of Imaging Findings of Brucellosis: A Pictorial Essay,” Canadian Association of Radiologists Journal, vol. 63, no. 1, pp. 35–42, 2012. doi: 10.1016/j.carj.2010.09.011 Available: https://doi.org/10.1016/j.carj.2010.09.011
[7] L. S. Rabushka, A. Kawashima, and E. K. Fishman, “Imaging of the Spleen: CT with Supplemental MR Examination,” RadioGraphics, vol. 14, no. 2, pp. 307–332, 1994. doi: 10.1148/radiographics.14.2.8190956 Available: https://doi.org/10.1148/radiographics.14.2.8190956
[8] S. Lipka, R. Zawadzki, Z. G. Kilicoglu, J. Zajkowska, U. Łebkowska, and B. Kubas, “Imaging of Spinal and Central Nervous System Brucellosis: A Review,” Polish Journal of Radiology, vol. 90, pp. e161–e169, 2025. doi: 10.5114/pjr/200911 Available: https://doi.org/10.5114/pjr/200911
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