Imaging of plant-thorn synovitis

We describe a case of plant-thorn synovitis of the elbow resulting from a thorn injury. This caused recurrent pain and swelling of the elbow over a 3-month period. A magnetic resonance imaging examination was initially requested to exclude septic arthritis, and demonstrated a joint effusion, synovitis, and a 2-cm linear opacity embedded in the synovium. Ultrasound was performed prior to surgery to confirm these findings and provide accurate localization of the thorn fragment, later removed at surgery. To our knowledge this is the first example of this condition that has been confirmed by radiological imaging prior to surgery. Received: 12 August 1999 Revision requested: 31 October 1999 Revision received: 1 May 2000 Accepted: 11 May 2000     

Pigmented villonodular synovitis of the hip presenting as a retroperitoneal mass

We present an unusual case of diffuse pigmented villonodular synovitis (PVNS) of the hip presenting as a large retroperitoneal mass in an asymptomatic 39-year-old man. Initial imaging characteristics and findings on core needle biopsy suggested soft tissue sarcoma. However, incisional biopsy showed findings of PVNS. The patient underwent radical synovectomy and total joint replacement, with no change in the large retroperitoneal component after 15 months of follow-up. Received: 15 June 2000 Revision requested: 8 September 2000 Revision received: 14 March 2001 Accepted: 15 March 2001     

Juxta-articular hemangioma of long bone

We report on a rare case of an intraosseous hemangioma involving the proximal tibia in a 70-year-old man. Radiographically, the lesion was a well-defined osteolytic lesion with marginal sclerosis. The CT images demonstrated a well-defined osteolytic lesion with partial cortical breakthrough. T1-weighted MR images showed a hypointense lesion, while T2-weighted images revealed hyperintense areas, with internal, hypointense septa. Gadolinium-enhanced T1-weighted images showed lattice-like enhancement of the lesion. Received: 28 December 1999 Revision requested: 3 March 2000 Revision received: 23 May 2000 Accepted: 26 May 2000     

Bilateral metachronous periosteal tibial amyloid tumors

Localized primary periosteal amyloid tumors are extremely rare. A case of bilateral tibial amyloid tumor is presented. A 62-year-old woman initially presented with a painful mass in the anterior aspect of the right leg. There was no evidence of underlying systemic disease, including chronic infection or malignancy. Based on the results of resistance with Congo red staining to treatment with potassium permanganate and positivity for kappa light chain, we classified this particular case as AL-type amyloidosis. The patient noticed a swelling in the opposite leg 2 years later. The second tumor was also an AL-type amyloidoma. Amyloid tumors are generally solitary. This is the first case of bilateral periosteal amyloid tumors of the AL-type occurring in the tibiae. Received: 10 November 1999 Revision requested: 15 November 1999 Revision received: 6 March 2000 Accepted: 9 March 2000     

Intra-articular regional migratory osteoporosis of the knee

We report a case of lntra-articular regional migratory osteoporosis of the knee in a 53-year-old man. The case demonstrates an unusual pattern of migration of the marrow edema within the knee joint. This phenomenon has received scant attention in the radiological literature. Received: 9 July 1999 Revision requested: 24 August 1999 Revision received: 6 October 1999 Accepted: 8 October 1999     

Primary pulmonary osteogenic sarcoma

A 56-year-old man initially presented to his family physician with tingling in the fingertips of his left hand. A chest radiograph revealed a left upper lobe mass. Local resection found a soft tissue osteogenic sarcoma. This is a report of a rare case of primary pulmonary osteogenic sarcoma. Received: 12 May 1999 Revision requested: 28 June 1999 Revision received: 11 January 2000 Accepted: 12 January 2000     

Complete rupture of the distal semimembranosus tendon with secondary hamstring muscles atrophy: MR findings in two cases

Complete rupture of the hamstring muscles is a rare injury. The proximal musculo-tendinous junction is the most frequent site of rupture. We present two cases of complete rupture of the distal semimenbranosus tendon, which clinically presented as soft-tissue masses. MR imaging permitted the correct diagnosis. There has been only one other such case reported. Received: 15 October 1999 Revision requested: 6 February 2000 Revision received: 8 March 2000 Accepted: 13 March 2000     

Primary hemangiopericytoma of the tibia: MR and angiographic correlation

The Magnetic Resonance Imaging (MRI) appearances of primary osseous hemangiopericytoma (HPC) have been rarely described. We report on a 46-year-old Chinese man with primary osseous HPC of the right tibia. The characteristic vascular distribution of this tumor, presenting with a ”spoke-wheel” appearance on MR images and with angiographic correlation, is described. Although not pathognomonic, this MR appearance may be an important finding in suggesting the diagnosis of osseous HPC. Received: 3 March 1999 Revision requested: 26 April 1999 Revision received: 13 September 1999 Accepted: 15 September 1999     

Solitary infantile myofibromatosis involving the clavicle

A rare case of solitary infantile myofibromatosis of bone is reported in the right clavicle of a 15-year-old boy. A radiograph demonstrated an osteolytic lesion with a sharp margin and a sclerotic rim. CT revealed a circumscribed lesion with slight expansion of the cortex. On MRI the lesion appeared isointense to muscle on T1-weighted images, bright on T2-weighted images, and showed marked gadolinium enhancement. The patient was well, without evidence of recurrence or metastasis, 4 years and 5 months following resection. Received: 11 August 1998 Revision requested: 5 October 1998, 18 March 1999 Revision received: 15 March 1999, 23 April 1999 Accepted: 28 April 1999     

Intra-articular entrapment of the medial collateral ligament: radiographic and MRI findings

Displacement of the medial collateral ligament (MCL) into the medial knee joint is an extremely rare finding associated with MCL tears, and is easily diagnosed on magnetic resonance imaging. A case of intra-articular interposition of the MCL during a severe knee injury is presented. A radiolucent ”fat stripe” sign and adjacent skin dimpling on radiographs may be relatively specific indicators of this injury. Received: 18 March 1999 Revision requested: 17 May 1999 Revision received: 1 July 1999 Accepted: 2 July 1999     

In vitro and in vivo spin echo diffusion imaging characteristics of synovial fluid: potential non-invasive differentiation of inflammatory and degenerative arthritis

Objective. This study was undertaken to analyse the diffusion characteristics of synovial fluid in degenerative and inflammatory arthropathies. Design and patients. Ten in vitro specimens of synovial fluid from patients with both degenerative and inflammatory arthropathy were studied at body temperature with a navigator-corrected spin echo diffusion sequence (B values 0–512 s/mm²), on a Philips 1.5-T Gyroscan. Subsequently synovial fluid from knee joint effusions of 25 patients (10 patients with osteoarthritis, 10 patients with effusions following trauma and 5 patients with effusions secondary to inflammatory arthritis) was evaluated with the same navigator-corrected spin echo diffusion sequence. Results. Both in vitro and in vivo study demonstrated decreased diffusion in patients with effusions secondary to degenerative joint disease (less than 2.40×10^–5 cm²/s) relative to patients with effusions accompanying knee trauma (greater than 2.75×10^–5 cm²/s) and inflammatory arthritis (in vitro and in vivo greater than 3.00×10^–5 cm²/s). Conclusion. Synovial fluid in degenerative arthritis shows less diffusion or free water movement than synovial fluid in inflammatory arthritis. Diffusion characteristics of synovial fluid may be used to predict the nature of the underlying form of arthritis in patients presenting with knee joint effusions. Received: 22 October 1999 Revision requested: 10 January 2000 Revision received: 10 March 2000 Accepted: 14 March 2000     

Erdheim-Chester disease with intramuscular lipogranuloma

We report on a rare manifestation of Erdheim-Chester disease with intramuscular lipogranuloma. The patient was a 66-year-old man who noted a soft tissue mass in the right quadriceps femoris muscle. Radiographs revealed symmetrical osteosclerosis in the diametaphysis of both femora and tibiae. An open biopsy revealed a proliferation of lipid-laden histiocytes in the femoral bone marrow and the quadriceps femoris muscle. To our knowledge, this is the second case of Erdheim-Chester disease involving muscle. Received: 4 October 1999 Revision requested: 18 November 1999 Revision received: 1 December 1999 Accepted: 2 December 1999     

Malignant chondroblastoma presenting as a recurrent pelvic tumor with DNA aneuploidy and p53 mutation as supportive evidence of malignancy

We report a rare case of malignant chondroblastoma, which presented in a 47-year-old man as a recurrent tumor, 18 years following wide excision of a typical pelvic chondroblastoma. Radiologic studies of the recurrent tumor showed a large, lytic, destructive lesion of the right pelvic bones and femur, with a pathologic fracture of the latter, a large pelvic soft tissue mass, and multiple pulmonary metastases. Biopsy tissue showed typical features of chondroblastoma, but also increased nuclear atypia, hyperchromasia, and pleomorphism, compared to the original tumor, and, most significantly, abnormal mitotic figures. Immunohistochemical studies of the recurrent tumor revealed p53 mutation and extensive proliferative activity, and flow cytometric studies showed DNA aneuploidy, none of which was present in the original tumor. The patient received chemotherapy and radiation, but died of disease eight months after presentation. We also review chondroblastoma in general, to assign this unusual lesion to a tumor subtype. Received: 29 March 1999 Revision requested: 27 April 1999 Revision received: 23 June 1999 Accepted: 29 June 1999     

Multifocal osteoblastoma of the hand

Osteoblastoma is a benign bone tumor with uncertain radiologic and typical histologic pattern that, in most cases, can be diagnosed without any problems. Usually, it is a solitary bone tumor. The case presented is a 9-year-old child with multiple osteoblastomas occurring in multiple bones of the right hand. The child had pain in his right hand for several weeks. On physical examination, no swelling or other symptoms were elicited. All lesions noted radiologically were treated by curettage, and in all the pattern of osteoblastoma was diagnosed. Received: 25 February 2000 Revision requested: 28 March 2000 Revision received: 7 June 2000 Accepted: 13 June 2000     

Intramuscular spindle cell hemangioendothelioma

Spindle cell hemangioendothelioma occurring in skeletal muscle is extremely rare. No reported studies have performed an imaging evaluation of intramuscular spindle cell hemangioendothelioma. We report on such a tumor arising in an unusual site, the right extensor digiti minimi, in a 46-year-old woman. An en bloc resection was performed and the patient has been disease free for 8 years. Radiologic imaging in the present case showed similar findings to those described in intramuscular hemangioma. Received: 11 January 1999 Revision requested: 18 March 1999 Revision received: 22 April 1999 Accepted: 23 April 1999     

Giant ancient schwannoma of the pelvis

A 43-year-old man with a large ancient schwannoma of the pelvis, presenting with varicose veins, is reported. Ancient schwannoma (neurilemmoma) is a benign tumour of nerve sheath origin characterised histologically by features of severe degeneration and which rarely can grow to a large size. Malignant transformation, though reported, is extremely rare. Received: 17 September 1999 Revision requested: 13 October 1999 Revision received: 22 June 2000 Accepted: 28 June 2000     

Epithelioid hemangioma of bone

Epithelioid hemangioma of bone is a rare type of angiomatous tumor. We report a documented case of epithelioid hemangioma occurring in the distal femur of a 35-year-old man. The clinical, radiographic, MR imaging and histologic findings of the tumor are described. Radiographs showed a well-defined expanding, osteolytic lesion in the diaphysis of the femur. MR imaging showed the lesion to have low signal intensity on T1-weighted images and intermediate signal intensity on T2-weighted images. Grossly the lesion was multiloculated with a dark brown, jelly-like content. To characterize the imaging appearances of epithelioid hemangioma, we reviewed the available literature on the subject. Received: 14 February 2000 Revision requested: 28 March 2000 Revision received: 31 May 2000 Accepted: 1 June 2000     

Juxtacortical chondromyxoid fibroma arising in an apophysis

We present a rare case of juxtacortical chondromyxoid fibroma arising in the lesser trochanter of the right femur which corresponds to an apophysis. Radiography showed a well-defined expansive lesion with a sclerotic margin measuring 5×3.5 cm in diameter in the lesser trochanter. On spin echo T1-weighted images, the lesion revealed low signal intensity similar to muscle. On spin echo T2-weighted images, the lesion revealed high heterogeneous signal intensity, which after gadolinium injection showed heterogeneous enhancement. The inner margin of the cortex was intact and adjacent bone marrow was of normal signal intensity. The outer margin of the lesion was also clearly defined and extension into adjacent soft tissue beyond the exophytic cortical outgrowth was not evident. Received: 1 March 2000 Revision requested: 28 March 2000 Revision received: 1 May 2000 Accepted: 8 May 2000     

Hemangioma of bone arising in the ulna: imaging findings with emphasis on MR

An 18-year-old woman presented with left elbow joint pain. Radiographs and computed tomographic scan showed a well-defined osteolytic lesion of the left ulna associated with a honeycomb appearance on the radiographs. Magnetic resonance images showed intermediate signal intensity on T1-weighted images and mixed intermediate and high signal intensities on T2-weighted images. Only the periphery of the lesion enhanced with intravenously injected gadolinium-diethylenetriamine pentaacetic acid. The lesion was curetted to avoid pathologic fracture, and a histologic diagnosis of cavernous hemangioma of bone was made. Hemangioma involving the ulna is rare, but should be included in the differential diagnosis of a radiographic osteolytic lesion with a honeycomb appearance. Received: 17 September 1999 Revision requested: 31 October 1999 Revision received: 10 December 1999 Accepted: 13 December 1999     

Metastatic bone tumor mimicking spontaneous osteonecrosis of the medial condyle of the femur: misleading appearance on MR imaging

We report a case of a metastatic bone tumor that mimicked spontaneous osteonecrosis of the medial condyle of the femur on magnetic resonance imaging. Received: 5 October 1999 Revision requested: 11 November 1999 Revision received: 10 January 2000 Accepted: 17 January 2000