Musculoskeletal tuberculosis typically originates in bones and joints and then tracks as an abscess into the soft tissues. The primary involvement of soft tissues is rare. We describe such a case of tuberculosis arising only in muscle.
An 80-year-old, previously fit and healthy, male was referred by a GP with a 4–6 week history of noticeable lumps developing on the outer aspect of his right thigh. These were noticed during a routine self- examination, largely asymptomatic apart from causing some pain and discomfort on pressure. Investigations: Blood investigations revealed slightly raised ESR and CRP values of 40 and 42, respectively. Microbiology and culture tests showed the presence of pus cells and that there was no organism growth. MR images are shown in figures. Ultrasound guided aspiration was performed and was sent for culture and sensitivity tests. ZN staining of the aspirate showed the presence of acid fast bacilli. The analysis is under way, but it seemed likely that the organisms detected pertained to conventional Mycobacterium Tuberculosis rather than to any atypical strains. No operative treatment was indicated due to the extensive nature of this cold abscess, so the patient was referred to a chest physician, who started him on the triple therapy of rifampicin, isoniazid and pyrazinamide according to the BTS guidelines.
Tuberculosis can be caused by typical (e.g. mycobacterium tuberculosis hominis or rarely bovis) or atypical strains which have recently become more common with occurrence of multidrug resistant strains and AIDS. Involvement of muscles in the tuberculous process without coexisting active skeletal or extra skeletal tuberculosis is rarely seen. Although the infection is presumed to spread to the musculoskeletal system through a focus, the prevalence of active pulmonary tuberculosis coexisting with musculoskeletal tuberculosis is only about 29%. A few reports have indicated that primary tuberculosis in muscle may be transmitted via syringes. Because of its multiplanar capability and a good contrast for soft tissue, MRI is ideal for evaluating soft tissue masses, including inflammatory and infectious diseases.
Primary intramuscular cold abscess in the thigh.
This case involves an 80-year-old male patient. MRI shows a focal abnormal signal shadow within the right thigh musculature. The main features of the lesion include:
No obvious signs of bone destruction or joint space involvement are seen, but clinical symptoms and other examinations are needed to rule out any bone-related spread.
Considering the patient’s underlying history (suspected or confirmed tuberculosis, immunological status), clinical symptoms (local pain, swelling, or systemic symptoms), and imaging findings, the following potential diagnoses are considered:
Given the patient’s history (possible tuberculosis or no clear alternative primary source), clinical presentation (chronic inflammatory symptoms), and imaging findings of an isolated intramuscular lesion exhibiting ring enhancement, the most likely diagnosis is:
Primary muscular tuberculosis infection (tuberculous myositis/tuberculous abscess).
Further confirmation can be obtained through laboratory tests (e.g., acid-fast staining, mycobacterial cultures/PCR, interferon-gamma release assays) or biopsy. If doubt remains, a further needle biopsy for pathological and microbiological evidence is necessary.
Based on the consideration of “tuberculous myositis/muscular tuberculous abscess,” the following treatment strategies are recommended:
The rehabilitation/exercise prescription, based on the FITT-VP principle (frequency, intensity, time, type, progression, and individualization), should be performed under safe conditions:
Disclaimer: This report is based solely on the provided imaging and clinical history for a preliminary analysis and does not replace in-person consultation or professional medical advice. Specific diagnosis and treatment plans must be made in conjunction with clinical practice under the guidance of a specialized physician.
Primary intramuscular cold abscess in the thigh.
