Figure 1
Initial finger X-ray
Right ring finger with PIPJ soft tissue swelling and joint space reduction.
Unusual presentation of an intra-articular osteoid osteoma: case report
SectionMusculoskeletal system
Case TypeClinical Cases
AuthorsBarros D'Sa IJ1, Lahiri A2
Connected authors
31 years, male
Clinical History
A 30-year-old man had 2½ years of painful swelling involving his right ring finger proximal inter-phalangeal joint (PIPJ) with restricted movement. There was no preceding injury, no exposure to tuberculosis (TB) or other medical history. There was, however, family exposure to TB. Some relief obtained with non-steroidal anti-inflammatory drugs (NSAIDS).
Imaging Findings
Initial X-ray showed PIPJ soft tissue swelling, no erosive change or focal bone lesion. Initial MRI showed peri-articular soft tissue/bone marrow oedema with small PIPJ joint effusion & no soft tissue tumour. Initial diagnosis was dactylitis/TB inflammatory mono-arthropathy. Initial synovial biopsy showed no evidence of malignancy, TB or sarcoid granuloma. Oral steroids gave minimal relief. Ultrasound guided steroid injection gave minor relief. There was significant synovitis and hypervascularity on pre-injection images.
Repeat MRI was similar to first MRI; bone marrow oedema at proximal phalanx/PIPJ with moderate tenosynovitis. Second synovial biopsy showed non-specific inflammation and no granuloma.
After PIPJ fusion using crossed K-wires, histology of localized bone curettage confirmed osteoid osteoma. The patient has been asymptomatic for 1 year since fusion.
CT examination post fusion showed satisfactory position of wires with no evidence of any features of osteoid osteoma (previously discussed).
Final X-ray after K-wire removal showed satisfactory evidence of healing post fusion.
Repeat MRI was similar to first MRI; bone marrow oedema at proximal phalanx/PIPJ with moderate tenosynovitis. Second synovial biopsy showed non-specific inflammation and no granuloma.
After PIPJ fusion using crossed K-wires, histology of localized bone curettage confirmed osteoid osteoma. The patient has been asymptomatic for 1 year since fusion.
CT examination post fusion showed satisfactory position of wires with no evidence of any features of osteoid osteoma (previously discussed).
Final X-ray after K-wire removal showed satisfactory evidence of healing post fusion.
Discussion
Osteoid osteomas are benign bone tumours of growing skeletons. [1] They constitute about 10% of benign bone neoplasms with classic symptoms of intermittent worsening pain mainly at night. 8% osteoid osteomas occur in order of decreasing incidence in the hand, phalanges, carpals and metacarpals.
Diagnosis is tricky with variable features on imaging.
[2] Plain films show classic small ovoid radiolucent lesions with surrounding sclerosis, also seen on CT. MRI shows prominent oedema with low/intermediate signal focus on T1 sequences indicating the nidus.
[3] Intra-articular lesions cause non-specific symptoms such as synovitis, decreased range of movement, joint effusion and lack of a focal sclerotic lesion on radiographs. In one series, 9 intra-articular lesions were shown in the hip, elbow, ankle and meta-tarsals.
[4] Osteoid osteomas in phalanges of the hand in another series describe absence of reactive bone, mono-articular arthritis, clubbing, macrodactyly, painless swelling and absence of bony lysis.
[5] Another series of 48 upper limb osteoid osteomas, 5 were in proximal phalanges, 4 were in distal phalanges. Radiographs were sufficient for diagnosis in 32/48. 16/48 with no X-ray evidence had a hot spot on bone scan.
This case highlighted diagnostic difficulties. The only typical feature in history was minor relief with NSAIDS. The overwhelming history, imaging (USS/MRI) pointed to an inflammatory mono-arthropathy with response to intra-articular steroid and two synovial biopsies excluding sarcoid and TB.
The imaging features were atypical. The X-ray showed soft tissue swelling suggestive of mono-articular arthritis. There was no evidence of reactive bone sclerosis or lysis. MRI showed bone marrow oedema on both sides of the PIPJ, but more prominent on the proximal side. There was a joint effusion and tenosynovitis pointing to an inflammatory arthropathy. With retrospect the only feature to suggest a potential nidus was a 1-2mm low signal focus on MRI centrally in the marrow oedema, (only visualized on perhaps 2 images in different planes), adjacent to the articular surface of the proximal phalanx at the PIPJ. Ultrasound confirmed hypervascularity with a joint effusion/tenosynovitis.
CT examination post fusion did not show evidence of potential nidus or sclerosis adjacent to the crossed K-wires. The post-removal X-ray showed satisfactory healing. If the nidus is removed, the patient should be asymptomatic for a significant time period.
This was an unusual presentation of intra-articular phalangeal osteoid osteoma with non-specific history/imaging features and initial histology. The intra-articular nature of the lesion, the lack of conclusive imaging features and previous histology and more common diagnoses in the differential made the diagnosis difficult.
Diagnosis is tricky with variable features on imaging.
[2] Plain films show classic small ovoid radiolucent lesions with surrounding sclerosis, also seen on CT. MRI shows prominent oedema with low/intermediate signal focus on T1 sequences indicating the nidus.
[3] Intra-articular lesions cause non-specific symptoms such as synovitis, decreased range of movement, joint effusion and lack of a focal sclerotic lesion on radiographs. In one series, 9 intra-articular lesions were shown in the hip, elbow, ankle and meta-tarsals.
[4] Osteoid osteomas in phalanges of the hand in another series describe absence of reactive bone, mono-articular arthritis, clubbing, macrodactyly, painless swelling and absence of bony lysis.
[5] Another series of 48 upper limb osteoid osteomas, 5 were in proximal phalanges, 4 were in distal phalanges. Radiographs were sufficient for diagnosis in 32/48. 16/48 with no X-ray evidence had a hot spot on bone scan.
This case highlighted diagnostic difficulties. The only typical feature in history was minor relief with NSAIDS. The overwhelming history, imaging (USS/MRI) pointed to an inflammatory mono-arthropathy with response to intra-articular steroid and two synovial biopsies excluding sarcoid and TB.
The imaging features were atypical. The X-ray showed soft tissue swelling suggestive of mono-articular arthritis. There was no evidence of reactive bone sclerosis or lysis. MRI showed bone marrow oedema on both sides of the PIPJ, but more prominent on the proximal side. There was a joint effusion and tenosynovitis pointing to an inflammatory arthropathy. With retrospect the only feature to suggest a potential nidus was a 1-2mm low signal focus on MRI centrally in the marrow oedema, (only visualized on perhaps 2 images in different planes), adjacent to the articular surface of the proximal phalanx at the PIPJ. Ultrasound confirmed hypervascularity with a joint effusion/tenosynovitis.
CT examination post fusion did not show evidence of potential nidus or sclerosis adjacent to the crossed K-wires. The post-removal X-ray showed satisfactory healing. If the nidus is removed, the patient should be asymptomatic for a significant time period.
This was an unusual presentation of intra-articular phalangeal osteoid osteoma with non-specific history/imaging features and initial histology. The intra-articular nature of the lesion, the lack of conclusive imaging features and previous histology and more common diagnoses in the differential made the diagnosis difficult.
Differential Diagnosis List
Intra-articular osteoid osteoma in proximal phalanx.
Intra-articular osteoid osteoma
Mono-articular inflammatory arthropathy
Final Diagnosis
Intra-articular osteoid osteoma in proximal phalanx.
References
[1] Chronopoulos E, et al. (2008) Osteoid osteoma of a metacarpal bone: A case report and review of the literature. J Med Case Reports 2: 285 (PMID: 18752665)
[2] Barbiera F, et al (2002) Intra-articular osteoid osteoma: diagnostic imaging in three cases. Radiol Med 103(5-6): 464-73 (PMID: 12207182)
[3] Szendroi M, et al (2004) Intraarticular osteoid osteoma: clinical features, imaging results and comparison with extraarticular localization. J Rheumatol 31(5):957-64 (PMID: 15124257)
[4] Burger I M, McCarthy E F (2004) Phalangeal osteoid osteomas in the hand: a diagnostic problem. Clin Orthop Relat Res (427): 198-203 (PMID: 15552158)
[5] Themistocleous G S, et al (2006) Osteoid osteoma of the upper extremity. A diagnostic challenge. Chir Main 25(2): 69-76 (PMID: 16841767)
Case information
| URL: | https://www.eurorad.org/case/11560 |
| DOI: | 10.1594/EURORAD/CASE.11560 |
| ISSN: | 1563-4086 |
Figure 5
Ultrasound PIPJ
Ultrasound PIPJ.
Significant vascularity on power Doppler around joint and the bone.
The PIPJ was injected with steroid.
Initial finger X-ray
Right ring finger with PIPJ soft tissue swelling and joint space reduction.
Dept of Radiology Sandwell & West Birmingham Hospitals, West Midlands UK
Dept of Radiology Sandwell & West Birmingham Hospitals, West Midlands UK
Ultrasound PIPJ
Ultrasound PIPJ.
Significant vascularity on power Doppler around joint and the bone.
The PIPJ was injected with steroid.
SWBH radiology
SWBH radiology
