Tuberculous lesions in bone are lytic with poorly defined margins that often cross the physes. However, symmetrical lytic lesions in bones due to tuberculosis are rare and only very few cases have been reported. The indolent course and progressive symptoms are the most consistent features of musculoskeletal tuberculosis and misdiagnosis is common. Osteopenia and joint effusion are common with articular involvement. As these lesions radiologically mimic bone cyst, osteoblastoma, osteosarcoma and metastatic bone disease1, biopsy is mandatory to confirm the diagnosis Cystic type of tuberculosis is rare and presents a difficult to diagnose problem. The purpose of this case report is to highlight the features for the diagnosis of cystic lesion of bone and to emphasize the importance of carrying out biopsy in such cases for the confirmation of diagnosis2. A 19-year-old male presented with pain and swelling of one month duration over the outer aspect of the right ankle. There was no history of constitutional symptoms, trauma or any recent strenuous activity.
The patient did not suffer from any significant medical illness. On examination there was some swelling and deep tenderness over the lateral malleolus. The ankle had a full range of pain free movements. On Plain radiographs Lytic, expansive focus was seen lying eccentrically in tibial metaphysic with disruption of cortex laterally. Extension to articular surface was noted. Margin showed thin zone of sclerosis. Overlying soft tissue swelling was noted. Ankle joint space appears maintained. Tarsal bones and their joints were grossly maintained. (Figure 1) All routine blood investigations including ESR and CRP were also normal. The patient failed to respond to conservative treatment. Further investigation with a bone scan revealed an increased uptake in the lower end of the tibia. Bone scan reported chondroblastoma right tibia as provisional diagnosis and advised biopsy for final diagnosis. (Figure 2) The patient underwent open biopsy for histological examination, culture and polymerase chain reaction (PCR) analysis.
Histology showed a few Langhans giant cells, but no bacilli were seen. PCR analysis showed Mycobacterium tuberculosis, but cultures failed to grow any organism. The diagnosis was confirmed by biopsy specimens. There was no evidence of pulmonary tuberculosis on chest radiograph. On the basis of clinical features, histology and PCR results, ant tubercular treatment were started. The cystic cavity was curetted to remove granulation tissue and pus. Bone graft was used to fill the bony defect. The patient responded to the treatment with complete resolution of symptoms. The patient recovered well without any deformity or restriction of movement, and was under regular follow-up for one year post operation. (Figure 2)
Tuberculosis is rampant and endemic in developing countries. The incidence of skeletal manifestation in tuberculosis is only 1-2%. Bones generally involved are the spine (dorso-lumbar), skull, shoulder girdle and hip bones. Tuberculosis of the bone, in general usually begins in the cancellous portion of the bones involved3 Multiple sites may be involved. However, symmetrical lytic lesions in bones due to tuberculosis are rare and only very few cases have been reported. As these lesions radiologically mimic bone cyst, osteoblastoma, osteosarcoma and metastatic bone disease, biopsy is mandatory to confirm the diagnosis. The advent of DNA amplification techniques such as the polymerase chain reaction may herald a promising new era in the prompt and accurate management of extrapulmonary tuberculosis 4. If osteoarticular tuberculosis is diagnosed and treated at an early stage, approximately 90-95% of patients achieve healing with near normal function. The mainstay of treatment is anti-tuberculous therapy and active assisted exercise of the involved joint throughout the period of healing 5. Cystic type of tuberculosis is rare and presents a difficult to diagnose problem. The purpose of this case report is to highlight the features for the diagnosis of bilateral symmetrical cystic lesions of bone and to emphasize the importance of carrying out biopsy in such cases for the confirmation of diagnosis.
“Conflict of interest: None.”
1. Yip KM, Lin J, Leung PC. Cystic tuberculosis of bone mimicking osteogenic sarcoma. Tuber Lung Dis 1996;77:566-8.
2. Levine SM, Marianacci EB, Kuttapuram SV. Tuberculosis of contralateral costotransverse joints. Skeletal Radiol 1997;26:741-3.
3 Straus CD. Tuberculosis of the flat bones of the vault of the skull. Surg Gynec Obstet 1933; 57:384-398.
4 Carrot ED, Clark JE, Cant AJ. Non-pulmonary tuberculosis Pediatr Respir 2001; 2:113-9.
5 Tuli SM. General principles of osteoarticular tuberculosis. Clin Orthopedic 2002; 398:11-19.
About the Author:
Dr Ramji lal Sahu
Associate professor, Department Of Orthopaedics, SMS and RI, Sharda University.
Greater Noida, U. P., India
Contact: Mobile no. 09871120703, Email firstname.lastname@example.org