Imaging tumors of the patella.

BACKGROUND: Patellar tumors are rare; only a few series have been described in the literature and radiographic diagnosis can be challenging. We reviewed all patellar tumors at one institution and reviewed the literature. MATERIALS AND METHODS: In an evaluation of the database at one institution from 1916 to 2009, 23,000 bone tumors were found. Of these, 41 involved the patella. All had imaging studies and microscopic diagnostic confirmation. All medical records, imaging studies, and pathology were reviewed. RESULTS: There were 15 females and 26 males, ranging from 8 to 68 years old (average 30). There were 30 benign tumors; eight giant cell tumors, eight chondroblastomas, seven osteoid osteomas, two aneurysmal bone cysts, two ganglions, one each of chondroma, exostosis, and hemangioma. There were 11 malignant tumors: five hemangioendotheliomas, three metastases, one lymphoma, one plasmacytoma, and one angiosarcoma. CONCLUSION: Patellar tumors are rare and usually benign. As the patella is an apophysis, the most frequent lesions are giant cell tumor in the adult and chondroblastoma in children. Osteoid osteomas were frequent in our series and easily diagnosed. Metastases are the most frequent malignant diagnoses in the literature; in our series malignant vascular tumors were more common. These lesions are often easily analyzed on radiographs. CT and MR define better the cortex, soft tissue extension, and fluid levels. This study presents the imaging patterns of the more common patellar tumors in order to help the radiologist when confronted with a lesion in this location.

The importance of radiographic imaging in the microscopic assessment of bone tumors.

INTRODUCTION: Primary bone tumors are rare and require a multidisciplinary approach. Diagnosis involves primarily the radiologist and the pathologist. Bone lesions are often heterogeneous and the microscopic diagnostic component(s) may be in the minority, especially on core needle biopsies. Reactive processes, benign, and malignant tumors may have similar microscopic aspects. For these challenging cases, the correlation of microscopic and radiologic information is critical, or diagnostic mistakes may be made with severe clinical consequences for the patient. The purpose of this article is to explain how pathologists can best use imaging studies to improve the diagnostic accuracy of bone lesions. DIAGNOSIS: Many bone lesions are microscopically and/or radiographically heterogeneous, especially those with both lytic and matrix components. Final diagnosis may require specific microscopic diagnostic features that may be present in the lesion, but not the biopsy specimen. A review of the imaging helps assess if sampling was adequate. The existence of a pre-existing bone lesion, syndrome (such as Ollier disease or multiple hereditary exostosis), or oncologic history may be of crucial importance. Finally, imaging information is very useful for the pathologist to perform accurate local and regional staging during gross examination. CONCLUSION: Close teamwork between pathologists, radiologists, and clinicians is of utmost importance in the evaluation and management of bone tumors. These lesions can be very difficult to interpret microscopically; imaging studies therefore play a crucial role in their accurate diagnosis.

Parosteal osteoliposarcoma: a new bone tumor (from imaging to immunophenotype).

INTRODUCTION: Parosteal osteosarcomas and well-differentiated liposarcomas (WDLPS) of soft tissue share several features: they are slowly progressive, locally aggressive tumors, tend to recur locally, and rarely or never metastasizes if not dedifferentiated. Their treatment is wide surgical resection. Microscopically, both are well differentiated tumors, very like their normal tissue counterpart. They share simple karyotypes with supernumerary ring chromosomes or giant marker chromosomes containing amplified 12q sequences including MDM2 and CDK4 genes, with subsequent overexpression of MDM2 and CDK4 proteins. We present the case of a parosteal osteoliposarcoma made of closely intermingled components of a low-grade osteosarcoma and a WDLPS. CASE: In a 34 year-old woman with a slowly growing mass of the arm, imaging revealed a large well-defined heterogeneous parosteal mass of the upper humerus, with two main components: bone at the base and fat at the periphery. Microscopically, these two components were consistent respectively with low grade osteosarcoma and WDLPS. Cells of the two components were labeled with anti-CDK4 antibody. No labeling with anti-MDM2 antibody and no signal detected with MDM2 FISH analysis were likely due overdecalcification. No frozen tumor tissue was available for FISH analysis nor array-CGH. DISCUSSION: Differential diagnoses of this new entity would be a well-differentiated liposarcoma with a low-grade osteosarcomatous component that originates from the soft tissues, ruled out on imaging, and an ossifying parosteal lipoma, ruled out on immunohistochemistry. CONCLUSION: This is the first description of a low-grade parosteal sarcoma with two components that morphologically and immunophenotypically demonstrate characteristics of a parosteal osteosarcoma and of a well-differentiated liposarcoma.

Imaging of bone tumors for the musculoskeletal oncologic surgeon.

The appropriate diagnosis and treatment of bone tumors requires close collaboration between different medical specialists. Imaging plays a key role throughout the process. Radiographic detection of a bone tumor is usually not challenging. Accurate diagnosis is often possible from physical examination, history, and standard radiographs. The location of the lesion in the bone and the skeleton, its size and margins, the presence and type of periosteal reaction, and any mineralization all help determine diagnosis. Other imaging modalities contribute to the formation of a diagnosis but are more critical for staging, evaluation of response to treatment, surgical planning, and follow-up.When necessary, biopsy is often radioguided, and should be performed in consultation with the surgeon performing the definitive operative procedure. CT is optimal for characterization of the bone involvement and for evaluation of pulmonary metastases. MRI is highly accurate in determining the intraosseous extent of tumor and for assessing soft tissue, joint, and vascular involvement. FDG-PET imaging is becoming increasingly useful for the staging of tumors, assessing response to neoadjuvant treatment, and detecting relapses.Refinement of these and other imaging modalities and the development of new technologies such as image fusion for computer-navigated bone tumor surgery will help surgeons produce a detailed and reliable preoperative plan, especially in challenging sites such as the pelvis and spine.

Biopsy for suspected spondylodiscitis.

BACKGROUND: Vertebral biopsy is fundamental in determining whether a spinal lesion is of infectious or neoplastic etiology. Accurate diagnosis is critical for proper medical and/or surgical treatment and consequently for the prognosis of the patient. CT-guided percutaneous spinal biopsy (CTSB) may minimize the risk of contamination and complications. AIM: To demonstrate the importance and efficacy of CTSB and subsequent microbiologic/histological examination in the diagnosis of spinal lesions, particularly for those of an infectious nature. MATERIALS AND METHODS: Two series of spinal infection patients. Prospective series of 69 patients (2009-2011), 24 of whom underwent CTSB. Retrospective series of 130 patients (1999-2008), 65 of whom underwent CTSB. All patients had microbiologic and histological testing of biopsy samples, when possible. RESULTS: For the 2009-2011 patient series, histological examination yielded a diagnosis in 81.8% of cases, microbiologic culture and PCR for Mycobacterium tuberculosis in 45.8%. For the 1999-2008 series, histological examination yielded a diagnosis in 69% of cases, culture in 38.5%. Spinal lesions in 4 patients with previous histories of malignancy were assumed to be metastatic and treated with radiation at outside institutions. After biopsy, all were revealed to be spondylodiscitis. CONCLUSIONS: Percutaneous CT-guided needle biopsy is the mainstay of diagnosis for spine lesions of unknown etiology, thus guiding appropriate treatment. Histological diagnosis, when possible, is critical before initiation of therapy and may be helpful in cases where cultures are negative. In the case of a spinal lesion of unknown origin, even in the setting of a previous malignancy, metastasis should not be assumed; infection and new primary lesions should always be considered as part of the differential diagnosis.

Severe osteolysis and soft tissue mass around total hip arthroplasty: description of four cases and review of the literature with respect to clinico-radiographic and pathologic differential diagnosis.

Periprosthetic osteolysis is a well known phenomenon caused by wear particle-induced bone resorption, particularly common and extensively reported in total hip arthroplasty. Its typical radiographic feature is a radiolucent area adjacent to an implant, sometimes associated with a soft tissue mass. Osteolytic changes may be caused by numerous other pathologic processes, including infection, metabolic disease, and neoplasia. Four cases of massive periprosthetic bone destruction associated with a large soft tissue mass around a failed total hip replacement are presented. In three cases, a diagnosis of periprosthetic osteolysis was correctly made and managed by revision surgery. However, in one case angiosarcoma of the ipsilateral hemipelvis went long unrecognized despite aggressive clinical course, requiring hind-quarter amputation and ultimately resulting in the patient's death. Periprosthetic malignancy in the form of either primary sarcoma or metastatic cancer is a very rare yet reported event in the setting of previous hip replacement, likely leading to catastrophic consequences when diagnosis is not established in a timely manner. The differential diagnosis of periprosthetic osteolysis should consider the entire spectrum of conditions that can present with radiolucent changes. Thorough review of patient's history and course of symptoms, along with careful evaluation of standard roentgenograms should be always performed and possibly integrated with imaging modalities such as CT, MRI, and bone scintigraphy in order to increase diagnostic accuracy. If uncertainty remains, biopsy should always be considered to rule out malignancy.

Intramedullary screw fixation of proximal fifth metatarsal fractures: a biomechanical study.

Intramedullary screw fixation is a popular technique for treatment of proximal fifth metatarsal fractures. The purpose of this study was to compare the fixation rigidity of a 5.5 mm partially threaded cannulated titanium screw, with presumed superior endosteal purchase, to a similar 4.5 mm screw. Acute fifth metatarsal fractures were simulated in cadavers, stabilized with intramedullary screws, and loaded to failure in three-point bending. The initial failure loads for the metatarsals fixed with 4.5 mm and 5.5 mm screws were not significantly different (332.4 N vs. 335.2 N, respectively), nor were the ultimate failure loads (849.8 N vs. 702.2 N, respectively). Based upon our results, maximizing screw diameter does not appear to be critical for fixation rigidity and may increase the risk of intraoperative or postoperative fracture.