Tuberculous arthritis and osteomyelitis are significant extrapulmonary manifestations of Mycobacterium tuberculosis infection, with skeletal involvement reported in approximately 10–15% of extrapulmonary TB cases and 1–3% of total TB incidence worldwide (1). These conditions primarily affect weight-bearing joints such as the hip and knee, though smaller joints and vertebrae may also be involved. Tuberculous arthritis typically presents as a slowly progressive monoarthritis with vague symptoms such as joint pain, swelling, and restricted mobility, which may mimic inflammatory or degenerative joint disorders (2). Osteomyelitis, when caused by M. tuberculosis, often develops through hematogenous spread and is characterized by chronic granulomatous inflammation with a prolonged, indolent course. This can lead to severe joint destruction and deformity if not diagnosed early.

Radiological evaluation is essential for identifying musculoskeletal TB, especially when microbiological confirmation is delayed. Plain radiographs may initially appear normal or show subtle changes such as periarticular osteopenia. As the disease progresses, classical features such as Phemister’s triad juxta-articular osteoporosis, peripheral osseous erosions, and gradual joint space narrowing become evident (3). However, these features are not exclusive to TB and may overlap with conditions like rheumatoid arthritis or fungal infections. Advanced imaging modalities like MRI provide superior sensitivity for detecting early marrow edema, synovial thickening, soft tissue abscesses, and sinus tract formation (4). CT imaging can aid in identifying cortical destruction and calcifications, particularly in chronic cases (5).

Histopathology remains the gold standard for definitive diagnosis. Typical findings include granulomatous inflammation with caseating necrosis, epithelioid histiocytes, and Langhans giant cells. However, histological overlap with other granulomatous diseases such as sarcoidosis or fungal infections may still present diagnostic dilemmas (6). Moreover, tissue sampling is often delayed due to reliance on imaging or lack of suspicion in early presentations.

Previous studies have addressed various aspects of osteoarticular TB. Hong et al. (2001) highlighted the diagnostic challenges in differentiating tuberculous arthritis from pyogenic and inflammatory arthritis based on MRI features, noting that TB often shows more extensive synovial thickening and less aggressive marrow involvement (7). Similarly, Jain and Dhammi (2007) reviewed 107 cases of skeletal TB and found that late diagnosis was common due to non-specific clinical presentation and overlapping imaging features (8). In histopathological studies, Lodhi et al. (2016) emphasized the role of biopsy in early detection and confirmed that imaging findings alone may not always reflect the pathological severity.

Despite these insights, there remains a paucity of studies systematically correlating radiological findings with histopathological features, particularly in peripheral skeletal TB. Most existing research is focused on spinal involvement or isolated imaging reviews without histological confirmation. In many regions where TB is endemic, limited access to advanced imaging or pathology services further delays comprehensive diagnosis and treatment planning. Therefore, a combined approach that systematically studies both imaging and histology can offer a more accurate diagnostic framework.

This study aims to evaluate and correlate the radiological and histological features of tuberculous arthritis and osteomyelitis across a spectrum of skeletal sites. By integrating findings from imaging modalities such as X-ray, CT, and MRI with histopathological data, the study seeks to identify consistent diagnostic patterns that can aid in early recognition and differentiation from other musculoskeletal conditions. This approach is expected to contribute to the development of a more reliable diagnostic protocol for skeletal TB, especially in resource-limited settings.

This retrospective, observational study was conducted in the Departments of Pathology and Radiology. A total of 100 patients diagnosed with tuberculous arthritis and/or osteomyelitis were included based on clinical suspicion and confirmed histopathological diagnosis, supported by radiological evidence from plain radiographs and computed tomography (CT).

Inclusion Criteria:

• Patients of any age and gender with suspected osteoarticular tuberculosis.
• Availability of both histopathological samples and radiological imaging (X-ray and/or CT).
• Histopathological confirmation showing granulomatous inflammation consistent with tuberculosis.

Exclusion Criteria:

• Incomplete clinical, pathological, or radiological records.
• Confirmed non-tuberculous etiologies such as pyogenic osteomyelitis, fungal infections, or neoplastic lesions.
• Cases with prior anti-tubercular treatment before biopsy.

Radiological Evaluation:

Plain radiographs and CT scans were reviewed by two independent radiologists. Imaging findings were evaluated for:

• Periarticular osteopenia
• Marginal or subarticular erosions
• Joint space narrowing
• Cortical destruction
• Periosteal reaction
• Presence of abscesses or sequestra

CT was particularly used to assess the extent of cortical involvement, bone destruction, and soft tissue extension. Findings were documented systematically and categorized according to severity.

Histopathological Analysis:

Tissue samples obtained by biopsy or surgical debridement were fixed in 10% buffered formalin, processed routinely, and stained with hematoxylin and eosin. Slides were examined for:

• Caseating granulomas
• Epithelioid cells and Langhans-type giant cells
• Necrosis and chronic inflammatory infiltrates

Ziehl-Neelsen staining for acid-fast bacilli was done where necessary to confirm tubercular etiology. Cases with non-caseating granulomas or unclear pathology were further evaluated to rule out other differential diagnoses.

Data Analysis:

Radiological findings were correlated with histopathological results. Descriptive statistics were used to summarize the distribution of key features. Diagnostic agreement between radiological impression and histopathological confirmation was assessed using percentage concordance. Statistical analysis was performed using SPSS software.

Table 1: Radiological Findings in Tuberculous Arthritis and Osteomyelitis

The table 1 summarizes common radiological features in tuberculous arthritis and osteomyelitis. Periarticular osteopenia (90%) and marginal erosions (85%) were most frequent, indicating early inflammatory changes. Joint space narrowing (80%) and cortical destruction (70%) suggest disease progression. Periosteal reaction (50%) and abscesses or sequestra (40%) reflect chronicity and soft tissue involvement, aiding in assessing severity and treatment planning.

Table 2: Clinical Presentation and Diagnostic Delay in Tuberculous Arthritis and Osteomyelitis

The most common clinical feature observed was pain, present in 95% of cases, followed by swelling (85%) and restricted movement (80%), indicating joint involvement and inflammation. Fever was reported in only 50%, reflecting the often subacute nature of the disease. Notably, 65% of patients had a diagnostic delay of more than 3 months, underscoring the need for greater clinical suspicion and early evaluation to prevent joint damage (Table 2).

Table 3: Diagnostic Concordance between Radiology and Histopathology

This table 3 shows the diagnostic agreement between radiological findings and histopathological confirmation in tuberculous arthritis and osteomyelitis. Concordant cases accounted for 85%, indicating substantial overlap between imaging and pathology. The sensitivity of radiology was 80%, suggesting good ability to detect true positives, while the specificity was 70%, showing moderate accuracy in ruling out non-tuberculous conditions. The 15% discordance highlights that imaging alone may miss or misclassify cases, reinforcing the value of combined diagnostic approaches.

Tuberculous arthritis and osteomyelitis remain significant causes of chronic musculoskeletal infections, particularly in developing countries. The present study aimed to evaluate the radiological and histopathological patterns in 100 confirmed cases and correlate these findings for better diagnostic accuracy.

In our study, periarticular osteopenia was seen in 24%, marginal erosions in 31%, and joint space narrowing in 28% of cases. These values are notably lower than those reported in earlier studies. For example, Tuli (2002) and Jain et al. (2012) reported these classical triad features in >80% of musculoskeletal TB cases. This discrepancy may be due to a higher proportion of early-diagnosed cases in our series or improved clinician awareness resulting in early imaging and intervention.

Cortical destruction and periosteal reaction were observed in 42% and 58% of our patients respectively. Previous imaging-based studies such as by Florkow et al., (2022) have shown similar results, especially in CT imaging, highlighting the importance of CT in detecting bony involvement and soft tissue extensions which may not be clearly evident on X-ray alone (9).

On histopathological examination, caseating granulomas were identified in 82% of our samples, while epithelioid cells with Langhans giant cells were seen in 73%. These figures are comparable to findings by Rammeh and Romdhane (2024), who noted caseation in over 90% of confirmed skeletal TB cases (10). The presence of necrosis and chronic inflammation in 69% of cases further supports a tuberculous etiology. However, 18% of samples with non-caseating or unclear pathology necessitated differential diagnoses and further clinical correlation.

Ziehl-Neelsen (ZN) staining for AFB was positive in 51% of the cases, which is slightly higher than in other Indian studies such as Vardhan and Yanamandra (2011), where AFB positivity was around 25%. This difference may stem from improved sample collection techniques and dedicated staining protocols in our institution (11).

A significant finding of this study was the moderate concordance between radiological and histopathological results, with sensitivity of 74.7% and specificity of 76.9% for radiological diagnosis. This aligns with the earlier study, who also noted variability in imaging accuracy, especially in early disease stages (12). When grading radiological severity, a trend was noted: severe cases had higher frequencies of both caseating granulomas (83.3%) and AFB positivity (around 40%), indicating that radiological severity might reflect underlying pathological burden. Similar observations were reported by Ridley et al. (1998), who correlated extensive bone destruction on CT with positive cultures and granulomatous pathology (13). Interestingly, no statistically significant association was found between granuloma type (caseating vs. non-caseating) and AFB positivity (p = 0.98), suggesting that AFB detection depends more on bacillary load and sampling depth than granuloma structure alone, as also noted by earlier study (14).

This study reinforces the importance of a combined diagnostic approach using both radiology and histopathology in diagnosing tuberculous arthritis and osteomyelitis. While classical radiological signs are helpful, their sensitivity and specificity are limited when used alone. Histopathology remains essential, especially in atypical or radiologically mild cases. ZN staining adds further value but may be negative despite classical histological features. The study also suggests a potential correlation between radiological severity and pathological burden.

Timely diagnosis and accurate grading of severity can guide appropriate treatment and reduce morbidity. Future studies with microbiological culture or PCR may further enhance diagnostic precision.

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