A previously well 21 year old East Timorese male presented to his local medical officer with a 2 month history of right elbow pain, associated with swelling and progressive limitation of movement. He also reported a 6 kg loss of weight during this time, but denied any other constitutional symptoms.
He appeared well, was afebrile, and had no abnormality on chest or abdominal examination. Examination of the right elbow revealed a firm, tender swelling, approximately 2 cm in diameter, over the lateral humeral epicondyle, with associated limitation of elbow flexion to 60 degrees.
Initial investigation with plain XR of the right elbow joint revealed a joint effusion (Figure 1). As these findings were non-specific, further evaluation with different imaging modalities was undertaken.
Ultrasound examination of the elbow showed a large joint effusion (Figure 2). Scintigraphic imaging with Tc99m three phase bone scanning demonstrated increased blood pool activity, and diffusely increased osteoblastic activity, involving the right elbow joint, particularly the distal humerus and ulna, as well as the distal left radius (Figure 3).
CT scan confirmed the presence of cortical erosions involving the right lateral epicondyle of the humerus and the ulna. Further, there was increased attenuation within the proximal medullary shaft of the ulna, and diffuse soft tissue thickening around the proximal ulna and radial head, with an associated joint effusion (Figure 4).
Further functional imaging with Thallium 201 chloride revealed intense early uptake in the right lateral epicondyle of the humerus and proximal ulna (Figure 5A). The delayed 4 hour images demonstrated tracer retention (Figure 5B). The delayed whole body views showed further abnormal thallium retention involving the mediastinum, para-aortic regions of the abdomen, the left inguinal region and the distal left radius (Figure 6).
MR demonstrated erosive changes involving the lateral epicondyle, a loculated joint effusion and thickening and enhancement of the joint capsule and the annular ligament of the superior radio-ulnar joint. These changes suggested either a neoplasm or possibly infection (Figure 7).
The patient was therefore referred to the Bone and Soft Tissue Sarcoma service for further investigation.
Biopsy of the right elbow joint demonstrated chronic synovial inflammation and numerous polymorphonuclear cells in the synovial fluid, but no malignant cells (Figure 8). Microbiological examination, including staining for acid-fast bacilli and fungi, revealed no organisms.
CT scanning of the chest, abdomen and pelvis, performed in light of the thallium findings, revealed extensive retroperitoneal lymphadenopathy. The lymphadenopathy was characterised by peripheral enhancement with prominent central areas of low attenuation (Figures 9 and 10).
Subsequent CT guided biopsy of the retroperitoneal lymphoid tissue revealed necrotising granulomatous lymphadenitis indicative of Mycobacterium tuberculosis infection (Figure 11). While no acid fast bacilli were visible on Ziehl-Nielsen staining, polymerase chain reaction was positive for M. tuberculosis DNA. The lymph node biopsy specimens cultured M. tuberculosis after 6 weeks.
A final diagnosis of disseminated extrapulmonary tuberculosis was therefore made. Anti tuberculous therapy was commenced with good clinical response.