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Case of the month |
1 Departments of Medicine and Clinical Science
3 Orthopedic Surgery, Graduate School of Medical Sciences
2 Department of Endoscopic Diagnosis and Therapeutics, Kyushu University Hospital, Fukuoka, Japan
Correspondence: Yukihiko Jo MD, Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
A 42-year-old male was admitted to hospital because of right leg pain. He had a 14-year history of Crohn's disease with ileocolitis. He had beensuffering from pain in the distal part oftheright leg and both knees for several months. Non-steroidal anti-inflammatory drugs did not relieve the pain. On admission, he had redness and tenderness in the right lower leg. Laboratory investigations showed leucocytosis (11.36x103 µl-1) and an elevated erythrocyte sedimentation rate (33 mm h-1).
Bone scintigraphy (Figures 1a
,b) and MRI (Figures 2a,b) were performed on this patient.
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Bone scintigraphy showed increased uptake of radionuclide in the proximal portion of the right second rib, the middle and distal portion of the right tibia, and the proximal portion of the left tibia (Figures 1a
,b). Sagittal MRI of the right tibia showed low signal intensity on T1 weighted images (Figure 2a) and high signal intensity on T2 weighted images (Figure 2b) at a site that corresponded to the focus of increased uptake seen on bone scintigraphy.
The differential diagnosis includes osteomyelitis and neoplasm. Bone marrow biopsy from the right tibia showed neutrophil infiltration with plasma cells, consistent with subacute osteomyelitis, with no evidence of malignant change. Culture of the biopsy material was sterile. Antibiotic therapy (ceftriaxone and ciprofloxan) did not affect his symptoms or laboratory data. Subsequent treatment with prednisolone (10 mg day-1) was effective to some degree. A diagnosis of chronic recurrent multifocal osteomyelitis (CRMO) was made on the basis of the clinical symptoms, the appearances on bone scintigraphy and MRI, the laboratory data and the pathological findings. After discharge, he experienced episodes of exacerbation that lasted for a few weeks. Repeated bone scintigraphy 2 years after the initial investigation showed that radionuclide uptake in the right tibia and the proximal portion of the left tibia had decreased (Figure 3).
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Bacterial osteomyelitis originating from abdominal or rectal abscess occurs in patients with inflammatory bowel disease [4], and CRMO has rarely been reported in this condition [3, 4].
The radiographic appearances of CRMO consist of osteolytic lesions with surrounding sclerosis. However, it is difficult to detect active inflammation within bones that show these radiographic manifestations. MRI is more sensitive than plain radiography for assessing the extent and activity of the disease, even in chronic or subclinical lesions. During active phases, bone marrow involvement results in low signal intensity on T1 weighted images and high signal intensity on T2 weighted images [5]. CRMO is not usually accompanied by abscess formation or soft tissue inflammation, which are features of bacterial osteomyelitis. The changes in signal intensity in CRMO return to normal with improvement of the disease [5]. However, bone biopsy is sometimes required to exclude an infectious aetiology or a neoplastic lesion.
CRMO is seen as a focus of increased radionuclide uptake on bone scintigraphy. Although CRMO typically occurs at multiple sites, clinical symptoms may initially develop at a single site. Asymptomatic foci and symmetrical lesions are sometimes seen on whole body radionuclide imaging. Bone scintigraphy is also useful in the assessment of clinical response to therapy [6].
While antibiotic therapy is not effective for clinical symptoms, non-steroidal anti-inflammatory drugs and corticosteroids relieve the pain in some cases [2, 3]. Immunosuppressive agents have also been tried in other cases [4]. CRMO may be overlooked in cases of inflammatory bowel disease, or misdiagnosed as arthropathy complicating inflammatory bowel disease, or infectious osteomyelitis.
Received for publication July 18, 2000. Revision received August 21, 2000. Accepted for publication August 31, 2000.
References
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