Tuberculous Osteomyelitis of the Sternum: A Comprehensive Review

Introduction

Tuberculous osteomyelitis of the sternum is a rare manifestation of extrapulmonary tuberculosis, accounting for less than 1% of all cases of osteoarticular tuberculosis. Although rare, delayed diagnosis can lead to significant morbidity, including chronic pain, deformity, and mediastinal metastasis. This condition should be actively suspected, especially in patients presenting with chronic anterior chest wall pain that does not respond to conventional treatment.

Case Overview

A 36-year-old male presented with anterior chest wall pain persisting for two months. Initially diagnosed and treated as costochondritis, the patient failed to respond to treatment. Pain became localized to the midline chest wall.

[Figure 1]: Sternum lateral X-ray – No obvious bony abnormality detected.
[Figure 2]: Ultrasound – Cortical erosion in the lower body of the sternum with abnormal soft tissue exhibiting high vascularity.
MRI (performed next day) – Confirmed cortical destruction and retrosternal fluid collection (8 mm thickness).
FNA – Non-diagnostic due to inadequate material.
Open biopsy – Histopathology confirmed tuberculous osteomyelitis.

Etiology

Tuberculous osteomyelitis of the sternum is caused by Mycobacterium tuberculosis. Infection can occur through:

Hematogenous spread from a distant TB focus (commonly the lungs).
Direct extension from nearby lymph nodes or mediastinal structures.
Post-traumatic or post-surgical inoculation, though rare.

Pathophysiology

After M. tuberculosis reaches the sternum via the bloodstream or contiguous spread, the bacteria induce a granulomatous inflammatory reaction. Caseating necrosis gradually erodes the cortical bone, leading to:

Cortical destruction
Periosteal reaction
Adjacent soft tissue masses or abscesses
Retrosternal fluid collection which can compromise mediastinal structures if untreated.

Epidemiology

Incidence: Rare, <1% of skeletal TB cases.
Risk factors: Immunosuppression (HIV, chronic illness), endemic TB regions, previous TB infection, and close TB contact.
Demographics: More common in males aged 20–40 years, but can occur in all age groups.

Clinical Presentation

Typical symptoms include:

Persistent anterior chest wall pain
Localized swelling or tenderness over the sternum
Sometimes associated with low-grade fever, night sweats, and weight loss
Rarely, draining sinus tracts in chronic cases

In this patient, isolated midline chest pain without systemic symptoms initially.

Imaging Features

[Figure 1] Sternum lateral X-ray – Often normal in early disease due to slow progression.
[Figure 2] Ultrasound – Cortical erosion with hypervascular soft tissue changes.
MRI – Gold standard for early detection; identifies:

Bone marrow edema
Cortical destruction
Soft tissue involvement
Retrosternal collections (abscesses)
Relationship with mediastinal structures

CT is also valuable for assessing cortical destruction and surgical planning.

Treatment

First-line therapy is anti-tubercular treatment (ATT) for 6–12 months:

Intensive phase: Isoniazid, Rifampicin, Pyrazinamide, Ethambutol
Continuation phase: Isoniazid, Rifampicin

Surgical intervention:

Indicated for diagnostic biopsy, large abscess drainage, or severe bony destruction.
In this case, an open biopsy was necessary due to an inconclusive FNA.

Prognosis

With timely diagnosis and appropriate ATT, prognosis is generally excellent.
Delayed diagnosis may lead to:

Chronic sinus formation
Sternoclavicular joint involvement
Mediastinitis
Pathological fractures

Quiz Section

Q1. Which imaging modality is most sensitive for early detection of sternal tuberculous osteomyelitis?
A) X-ray
B) Ultrasound
C) MRI
D) CT

Q2. What is the most common route of infection for tuberculous osteomyelitis of the sternum?
A) Direct trauma
B) Hematogenous spread
C) Post-surgical infection
D) Skin contact

Q3. Which histopathological finding is most characteristic of TB osteomyelitis?
A) Fibrous tissue proliferation
B) Neutrophilic infiltration
C) Caseating granulomas
D) Cartilage degeneration

Q4. What is the first-line treatment for sternal TB osteomyelitis?
A) Broad-spectrum antibiotics
B) Anti-tubercular therapy
C) Surgical excision
D) Steroid therapy

Answer & Explanation

1. Answer: C) MRI. Explanation: MRI detects early marrow changes and soft tissue involvement before cortical destruction is visible on X-ray.

2. Answer: B) Hematogenous spread. Explanation: The sternum is typically infected via hematogenous spread from a pulmonary focus.

3. Answer: C) Caseating granulomas. Explanation: TB infection classically produces granulomatous inflammation with caseation necrosis.

4. Answer: B) Anti-tubercular therapy. Explanation: ATT is the cornerstone; surgery is adjunctive when necessary.

Figure Captions

[Figure 1] Lateral X-ray of the sternum showing no obvious bony abnormality.

[Figure 2] Ultrasound image revealing cortical erosion in the lower sternum with adjacent hypervascular soft tissue.

References

[1] C. Tuli, “Tuberculosis of the skeletal system: Bones, joints, spine and bursal sheaths,” 5th ed., Jaypee Brothers Medical Publishers, 2016.
[2] P. Rasool, “Osteoarticular tuberculosis in children,” Int Orthop, vol. 26, no. 4, pp. 229–232, 2002.
[3] M. F. Khan et al., “Primary tuberculous osteomyelitis of the sternum,” Ann Thorac Surg, vol. 82, no. 5, pp. 1897–1899, 2006.
[4] S. Watts and P. Lifeso, “Tuberculosis of bones and joints,” J Bone Joint Surg Am, vol. 78, no. 2, pp. 288–298, 1996.
[5] V. Dhillon et al., “Tuberculosis of the sternum: A report of three cases,” J Bone Joint Surg Br, vol. 81, no. 4, pp. 599–602, 1999.
[6] S. K. Jain, “Tuberculosis of the sternum: A clinical study,” Indian J Tuberc, vol. 54, pp. 81–84, 2007.
[7] A. Shukla et al., “Primary sternal tuberculosis: Diagnosis and management,” Interact Cardiovasc Thorac Surg, vol. 7, no. 6, pp. 1125–1127, 2008.

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