Benign vascular lesions of bone: radiologic and pathologic features

 The benign vascular tumors of bone represent a diverse group of tumors that can present with a broad spectrum of clinical signs and symptoms. They can also present a significant diagnostic challenge due to their widely variable radiographic imaging and histologic features. Some of the tumors manifest as clearly benign lesions with tissue-specific diagnostic imaging features, while others have non-specific imaging features that may simulate malignant neoplasm. This article will provide a review of the nomenclature and the characteristic radiographic and pathologic features of the benign vascular lesions of bone. The information will aid in improving our diagnostic accuracy and enhance our understanding of the biologic potential of this diverse group of osseous lesions. Received: 14 May 1999 Revision requested: 17 June 1999, 6 October 1999 Revision received: 27 October 1999 Accepted: 27 October 1999     

Sclerotic bone metastases from sarcomatoid renal cell carcinoma

We present a case of sarcomatoid renal cell carcinoma with multiple sclerotic skeletal metastatic lesions. Renal cell carcinoma is frequently metastatic at presentation, with a high incidence of skeletal involvement, classically described as osteolytic. However, sclerotic or osteoblastic metastatic skeletal lesions from renal cell carcinoma are rare, with only two previous reports identified in the literature, neither of which involved the sarcomatoid variant of renal cell carcinoma. In our case the sclerotic metastases were characterized by bone scan, computed tomography (CT), magnetic resonance imaging (MRI), and histologic analysis. Received: 8 April 1999 Revision requested: 27 May 1999 Revision received: 24 June 1999 Accepted: 29 June 1999     

Intraventricular mass lesions of the brain

Intraventricular tumours represent a diverse group of lesions, some of them infrequent, with a wide variety of radiological features. Determination of their precise aetiology or origin can be difficult. Nevertheless, considering patient's age, location within the ventricles, and some specific radiological features, the radiologist should be able to narrow down the differential diagnosis. This paper reviews the characteristic radiological appearances of the diverse intraventricular lesions emphasising its differential diagnosis. Received: 6 July 1999; Revised: 5 August 1999; Accepted: 9 August 1999     

Adenosarcoma arising in hepatic endometriosis

We report a case of adenosarcoma arising in hepatic endometriosis. Both CT and MR scans demontrated a huge heterogeneous mass containing septated, thick-walled cystic lesions. After enlarged right hepatectomy, the patient was asymptomatic with no abnormalities at liver and abdominal CT scan at 2-year follow-up. Received: 5 August 1999; Revised: 17 December 1999; Accepted: 20 December 1999     

CT, MRI and MRS of Epstein-Barr virus infection: case report

We report MRI and proton MR spectroscopy (MRS) findings in a 12-month-old girl with Epstein-Barr virus encephalitis. CT and MRI showed focal lesions in the basal ganglia. MRS of the lesions showed decreased N-acetyl aspartate and elevation of some amino acids, indicating an infectious rather than ischemic etiology. This case illustrates the use of MRS to narrow differential diagnosis. Received: 9 July 1999 Accepted: 15 December 1999     

Unusual causes of spinal foraminal widening

Spinal neural foraminal widening is usually caused by benign lesions, most commonly neurofibromas. Rare lesions can also cause spinal neural foraminal widening. Computed tomography and/or MRI are the modalities of choice for studying the spinal foraminal widening. The present pictorial review describes six rare lesions, namely a lateral thoracic meningocele, a malignant fibrous histiocytoma, a tuberculous abscess, an osteoblastoma, a chondrosarcoma and a malignant tumour of the lung which caused spinal neural foraminal widening. Received: 23 November 1998; Revised: 4 March 1999; Accepted: 20 April 1999     

Can intravascular lymphomatosis mimic sinus thrombosis? A case report with 8 months' follow-up and fatal outcome

We report a case of intravascular lymphomatosis of the brain with 8 months' follow-up and fatal outcome. Several MRI investigations revealed variegated, rapidly changing infarct-like lesions and invasion of the walls of the superior sagittal sinus and deep veins. When disturbances of the venous outflow are detected with multifocal infarct-like lesions, intravascular lymphomatosis should be considered in the differential diagnosis. Brain biopsy may ensure the proper diagnosis ante mortem, but failure of biopsy is frequent, as in our case. Received: 22 February 1999/Accepted: 29 July 1999     

Chondromyxoid fibroma of the acromium with soft tissue extension

Chondromyxoid fibroma is an unusual, benign tumor of cartilaginous origin and represents less than 1% of all primary bone tumors. It usually involves the long bones around the knee joint or the flat bones of the pelvis or ribs. Soft tissue extension is also thought to be rare in these lesions. They are usually eccentrically located in the metaphyses of the long bones and centrally in the flat bones. The radiographic appearances are characteristically those of a single, lytic lesion with lobulated margins, septations, cortical expansion and a sclerotic rim. Histologically, they display a lobulated pattern with spindle-shaped cells lying within a myxoid matrix with areas of hyaline cartilage. The differential diagnosis includes giant cell tumor, chondroblastoma or enchondroma as well as chondrosarcoma. The rarity of these lesions may render the diagnosis difficult to make, especially when the lesion involves an unusual site such as the acromium. Received: 21 June 1999 Revision requested: 27 September 1999 Revision received: 27 October 1999 Accepted: 28 October 1999     

Imaging of acute injuries of the articular surfaces (chondral, osteochondral and subchondral fractures)

Fractures involving the articulating surfaces of bone are a common cause of chronic disability after joint injury. Acute fractures of the articular surface typically run parallel to the surface and are confined to the cartilage and/or the immediate subchondral cancellous bone. They should be distinguished from vertical or oblique bone fractures with intra-articular extension. This article reviews the mechanism of acute articular surface injuries, as well as their incidence, clinical presentation, radiologic appearance and treatment. A classification is presented based on direct inspection (arthroscopy) and imaging (especially MRI), emphasizing the distinction between lesions with intact (subchondral impaction and subchondral bone bruises) and disrupted (chondral, osteochondral lesions) cartilage. Hyaline cartilage, subchondral bone plate and subchondral cancellous bone are to be considered an anatomic unit. Subchondral articular surface lesions, osteochondral fractures and solely chondral fractures are different manifestations of impaction injuries that affect the articulating surface. Of the noninvasive imaging modalities, conventional radiography and MRI provide the most relevant information. The appropriate use of short tau inversion recovery, T1-weighted and T2-weighted (turbo) spin-echo as well as gradient-echo sequences, enables MRI to classify the various acute articular surface lesions with great accuracy and provides therapeutic guidance. Received: 5 April 1999 Revision requested: 6 May 1999 Revision received: 21 June 1999 Accepted: 12 July 1999     

Uptake of 111In-pentetreotide and 99mTc-labeled autologous granulocytes in Kimura’s disease

Uptake of ¹¹¹In-pentetreotide (OctreoScan) and ^{99 m}Tc-labeled autologous granulocytes by the lesions of a 37-year-old female from Thailand with Kimura's disease is described. This is a benign chronic inflammatory condition that is endemic in Asians. It is characterized by adenopathy and subcutaneous nodules mostly affecting the head and neck area or the salivary glands. Although these examinations have previously not been described in Kimura's disease, uptake of the radiopharmaceuticals in the lesions can be expected from their histological appearance. With increasing medical, social and economic interactions with Asia, it is important to recognize this cause of adenopathy, including its appearance at various nuclear medicine examinations. Received: 11 February 1999; Revised: 20 July 1999; Accepted: 6 August 1999     

Endometrial stromal sarcoma of the uterus: MR and US findings

We describe the MRI and US features of two patients with endometrial stromal sarcoma of the uterus. Both lesions appeared as voluminous polypoid masses within an expanded endometrial cavity on both US and MRI. They had mixed echotexture and heterogenous signal intensity on both T1- and T2-weighted sequences. T2-weighted images were most helpful in detecting the endometrial nature of the disease and its relationships with surrounding myometrium. Received: 29 March 1999; Revised: 10 August 1999; Accepted: 11 August 1999     

Diffusion-weighted MRI in cyclosporin A neurotoxicity for the classification of cerebral edema

Cyclosporin A, an immunosuppressive agent, is known to have neurotoxic effects, but until now, there has not been agreement on the underlying mechanism. Our report suggests, by using diffusion-weighted MRI, that the brain lesions caused by cyclosporin A, are probably related to vasogenic edema. This may explain the complete recovery of the lesions on imaging when cyclosporine therapy is stopped. Received: 22 December 1998; Revised: 8 March 1999; Accepted: 2 April 1999     

Cystic lesions of the pineal region – MRI and pathology

Pineal lesions are rare. Tumours in this location comprise 0.4–1 % of intracranial tumours. They grow mainly as solid-mass lesions, and cystic tumours are not common. On MRI, a cystic configuration is associated usually with non-neoplastic pineal lesions rather than with a tumour, but analysis does not allow cystic pineal tumours to be distinguished from glial cysts with certainty. We compared neuroradiological and pathological data from 13 cystic pineal lesions, analysing preoperative MRI. Formalin-fixed, paraffin-embedded surgical specimens were stained routinely and immunocytochemically, using the streptavidin-biotin-complex method. Histology revealed six pineocytomas, four glial cysts, an arachnoid cyst, a low-grade astrocytoma and a teratoma. Signal characteristics of pineocytomas were similar in many respects to those of glial pineal cysts. Histomorphological analysis allowed unambiguous discrimination between pineocytomas and glial pineal cysts. Received: 19 July 1999/Accepted: 3 September 1999     

Rapid chondrolysis after an intra-articular leak of bone cement in treatment of a benign acetabular subchondral cyst: an unusual complication of percutaneous injection of acrylic cement

Percutaneous injection of methylmethacrylate is now increasingly employed to treat bone lesions, both malignant and benign. However, the risks of this procedure are still to be fully established. In this report, we describe a case of rapid chondrolysis appearing after the intra-articular leakage of cement during injection of an acetabular subchondral cyst, resulting in hip replacement. Although the mechanism of such chondrolysis is unknown, this event suggests a chondrolytic effect of the acrylic cement. Thus, it is essential to systematically search for the presence of an intra-articular passage before injecting bone cement into a peri-articular cyst. This unusual complication highlights the need for rigorous evaluation of the benefits and risks of percutaneous injection of acrylic cement in the treatment of benign lesions, especially close to an articulation. Received: 30 September 1999 Revision requested: 1 December 1999 Revision received: 27 December 1999 Accepted: 27 December 1999     

Multiple small pseudoaneurysms complicating pancreatitis: angiographic diagnosis and transcatheter embolization

We report a case of retroperitoneal hemorrhage due to multiple, small pseudoaneurysms complicating a chronic alcoholic pancreatitis. Cross-sectional imaging with CT and US could not clearly depict these vascular lesions. Selective arteriography of the superior mesenteric and gastroduodenal arteries clearly showed the small pseudoaneurysms and definitive treatment was performed by transcatheter embolization using coils. Eight months after successful embolization, the patient is asymptomatic without any recurrent bleeding. Received: 18 June 1999; Revised: 13 October 1999; Accepted: 15 October 1999     

Oncogenic osteomalacia

The clinical, imaging, metabolic, histologic and biochemical aspects of oncogenic osteomalacia are reviewed. The bone and soft tissue tumor and tumor-like lesions associated with this paraneoplastic syndrome are discussed. The radiologist’s role in the diagnosis and evaluation of this entity is presented. Received: 11 November 1999 Revision requested: 30 December 1999 Revision received: 7 January 2000 Accepted: 10 January 2000     

Radiographic findings in tuberculosis of the calvarium

We reviewed the pattern of involvement of the calvarium by tuberculosis (TB) in five patients and the role of imaging in its management. Four patients presented with localised scalp swelling and one with generalized seizures. Radiographs revealed lucent lesions with minimal surrounding sclerosis in the frontal (2), parietal (2) and occipital (1) bones. CT showed lesions involving the entire thickness of the calvarium and accompanying contrast-enhancing soft tissue. The patient presenting with seizures had a ring-enhancing lesion in the parietal lobe in addition to the extra-axial lesions. Although radiographs in all cases demonstrated calvarial TB, CT showed the extent of the defect, involvement of adjacent soft tissues, and in one case an intra-axial lesion. Radiographs suffice for follow-up of these patients. Received: 23 July 1999 Accepted: 20 September 1999     

Two rare lumbar tumours with unusual MRI characteristics

We present two rare lumbar lesions with similar MRI features: high signal on T1-weighted and proton density images and low signal on T2-weighted images; a melanotic schwannoma, and a giant-cell tumour-like lesion. Melanin in the first case and haemosiderin and metahaemoglobin in the second were responsible for the MRI characteristics. Received: 25 August 1999/Accepted: 3 September 1999     

MR-guided percutaneous excisional and incisional biopsy of breast lesions

The aim of this study was the realisation and clinical application of MR-guided vacuum biopsy for percutaneous excisional and incisional biopsy of enhancing breast lesions. A breast biopsy system and procedure have been developed which allow precise and safe access to breast lesions in any location and use of vacuum biopsy (VB) under MR guidance. Fifty-one patients with 55 MR-detected lesions were examined. Verification of these diagnoses included re-excision histology of all 14 malignancies and for benign lesions retrospective correlation of histology and imaging, assessment of complete or partial removal of the enhancing area directly after VB (40 of 40 lesions) and follow-up MRI (33 of 40 lesions), which in contrast to conventional needle biopsy can be used as proof of representative removal. Fifty-four of 55 procedures (including 15 lesions ≤ 5 mm and another 26 lesions of 5–10 mm size) were successful. One failure was caused by incorrect use of the VB gun. Vacuum biopsy yielded 14 malignancies and 40 benign lesions. With the available verification techniques all diagnoses proved correct. Percutaneous VB became possible under MR guidance. With minimal invasion it allowed increased certainty and accuracy even for very small lesions. Received: 17 August 1998; Revised: 15 January 1999; Accepted: 10 February 1999     

Multiple infarcts in a patient with cerebral phaeohyphomycosis: CT and MRI

Phaeohyphomycosis is an uncommon disorder caused by a variety of saprophytic fungi having distinctive morphologic features. Central nervous system infection typically occurs in the absence of predisposing factors and usually manifest symptoms and signs of abscess formation. We describe an otherwise healthy young man whose presentation with cerebral phaeohyphomycosis was subacute meningitis and stroke. Neuroimaging studies revealed multiple parenchymal lesions having the characteristics of recent infarcts; several vascular territories were involved. The nature of these lesions was confirmed histologically at autopsy. To our knowledge, such radiologic appearances have not previously been reported in this condition. Received: 19 July 1999 Accepted: 10 August 1999