Imaging of intra-articular osteoid osteoma

Intra-articular osteoid osteoma accounts for approximately 13% of all osteoid osteomas and presents as a monoarthropathy. Radiographs commonly do not identify the nidus, and in this event, MRI is likely to be the next imaging investigation. MRI may show a variety of appearances depending upon the age of the lesion. This article illustrates the imaging features of intra-articular osteoid osteoma, with emphasis on MRI. CT remains the investigation of choice for identifying the nidus.     

Lymph node metastases from osteoblastic osteogenic sarcoma visible on plain films

The radiologic features of lymph node metastases from osteogenic sarcoma visible on plain films in two patients are described. In one patient the lymph node ossification was visible on presentation and in the other patient it was demonstrated six months after the initial diagnosis. The radiologic pattern in both cases was similar. Deposition of metastatic osteoid tissue in lymph nodes, to such a degree that it can be recognized on plain films, appears to be a distinctly uncommon complication of this malignant neoplasm. It is considered probable that this complication occurs with the osteoblastic type of osteogenic sarcoma. It is suggested that lymphography might be of value in the detection of such metastases at an earlier stage, thus influencing the plan of treatment     

骨样骨瘤的X线、CT和MRI表现和诊断价值

目的分析骨样骨瘤的X线、CT和MRI表现,评价它们的诊断价值。方法经手术病理证实,同时有X线、CT和MRI检查的骨样骨瘤22例,其中男19例,女3例。分析X线、CT和MRI对瘤巢和瘤巢周围改变的显示能力。结果X线、CT和MRI分别有17、22和20例表现为有一圆形或卵圆形小于2cm的瘤巢,瘤巢周围可有程度不一的骨质硬化、骨膜反应、软组织及骨髓腔水肿或相邻关节的肿胀。X线诊断的准确率为77.3%（17/22）;CT诊断的准确率为100%（22/22）;MR诊断的准确率为90.9%（20/22）。结论大多数的骨样骨瘤具有较典型的影像学表现,易于诊断,其中以CT对瘤巢的定位最为准确,单凭X线或MR的表现可因未能显示瘤巢而误、漏诊。     

Osteosarcoma pleural effusion: A diagnostic challenge with some cytologic hints

Pleural effusions can be the first manifestation, recurrence, or metastasis of small round cell sarcomas in children. The most common are Ewing sarcoma, neuroblastoma, and rhabdomyosarcoma. The cytomorphology is variable, the cells can be cohesive, single cells, small or large, morphologically mimicking lymphomas, carcinomas, melanomas, and mesothelioma depending on the sarcoma involved. Osteosarcomas are rare. Their rarity, variable histomorphologic features, immunophenotypic heterogeneity, being of osseous or extraosseous origin and focality of malignant osteoid matrix make their cytologic recognition a diagnostic challenge. They can be confused with small round cell sarcomas, may be misinterpreted as degenerative inflammatory cells, or masked by florid reactive mesothelial hyperplasia particularly in pleural effusions. However, attention to certain cytomorphologic features in smears and cellblock sections should raise suspicion. We report a case of a 9‐year‐old child who presented with cough, chest pain and breathing difficulty, left pleural effusion, a collapsed consolidated lower lung lobe, and a clinical impression of pneumonia. Pleural fluid cytology was initially reported as inflammatory effusion with florid reactive mesothelial hyperplasia. Tissue biopsy of the lung mass showed histomorphologic features consistent with osteosarcoma. A careful look at the cytology materials and cellblock sections showed helpful cytomorphologic features that were masked by florid reactive mesothelial cells and misinterpreted as degenerative inflammatory lymphocytes. An extracellular matrix was a helpful hint. Malignant pleural effusion secondary to osteosarcoma is rare. Cytologic examination may help reach the correct diagnosis if the smears and cellblock sections are carefully evaluated for certain helpful cytomorphologic features, particularly osteoid matrix.     

Definition and classification of renal osteodystrophy

One of the major complications that arise as a result of chronic kidney disease is that of ‘renal osteodystrophy.’ It is believed to be a multifactorial disorder of altered bone modeling. Bone biopsy occupies a central role in the differentiation of the various kinds of renal osteodystrophy based on histological findings. However, due to its limitations of being a rather invasive and costly procedure, it is performed rather infrequently. Therefore, scientists started to focus on alternative measures of classifying the various types, e.g., the parathyroid hormone (PTH). PTH has been used as an indicator of bone turnover, thereby dividing the diseases into those of high turnover and low turnover. To further our understanding of this particular disease entity, a unified definition and classification was formulated and adopted by well-renowned experts from both local and international scenes, and this is presented in some detail in this chapter. It is hoped, that such unification will enhance communication, facilitate clinical decision making, and promote the evolution of evidence-based clinical practice guidelines worldwide. (2)     

Diagnosis of osteoid osteoma using stir magnetic resonance imaging

Two patients with osteoid osteomas were evaluated with magnetic resonance imaging at 1.5 T using both conventional spin-echo (SE) and short TI inversion-recovery (STIR) sequences. On plain films the classic findings of a radiolucent nidus with a dense surrounding reactive zone of sclerosis were absent. The diagnosis was suspected on observing the presence of marked marrow oedema in the involved bone. Conventional SE images were unimpressive in detecting the bone marrow changes. Increased signal intensity indicating bone marrow oedema was striking on the STIR images and facilitated diagnosis. In cases of suspected osteoid osteoma which do not demonstrate the classic radiologic features, adding the STIR sequence to conventional SE magnetic resonance sequences to enhance detection of bone marrow change is recommended.     

Computed tomography in suspected osteoid osteomas of tubular bones

Six cases of suspected osteoid osteoma of tubular bones were evaluated by computed tomography (CT). In all cases a radiolucent nidus was clearly demonstrated. In two cases a radiodense center of the nidus was visualized. It is suggested that CT may replace conventional tomography in the evaluation of these lesions. Due to its ability to locate the lesion in the transverse plane, CT is superior for the exact planning of surgery to avoid unnecessary large or misdirected resections. Adequate window settings are essential in the evaluation of these lesions.     

Arthroscopic removal of a juxtaarticular osteoid osteoma of the talar neck

The authors report a case of a 21-year-old woman with osteoid osteoma of the talar neck that was treated with arthroscopic resection. The nidus was removed in one piece with grasping forceps, and histopathologic findings confirmed the preoperative diagnosis of osteoid osteoma. Postoperatively, the patient was immediately relieved of ankle pain and there was no recurrence at the 1-year follow-up. If possible, the nidus should be removed without the use of a motorized instrument to ensure the correct histolologic diagnosis.     

RAPIDLY GROWING TWELFTH RIB OSTEOID OSTEOMA

A case report is presented of a 10 year old girl who was treated for a twelfth rib osteoid osteoma that became radiologically apparent over a period of only 3 weeks     

Computer modelling of RF ablation in cortical osteoid osteoma: Assessment of the insulating effect of the reactive zone

Purpose: The aim was to study by computer simulations the insulating role of the reactive zone surrounding a cortical osteoid osteoma (OO) in terms of electrical and thermal performance during radiofrequency ablation (RFA). Material and methods: We modelled a cortical OO consisting of a nidus (10?mm diameter) enclosed by a reactive zone. The OO was near a layer of cortical bone 1.5?mm thick. Trabecular bone partially surrounds the OO and there was muscle around the cortical bone layer. We modelled RF ablations with a non-cooled-tip 17-gauge needle electrode (300?s duration and 90?°C target temperature). Sensitivity analyses were conducted assuming a reactive zone electrical conductivity value (σ_rz) within the limits of the cortical and trabecular bone, i.e. 0.02?S/m and 0.087?S/m, respectively. In this way we were really modelling the different degrees of osteosclerosis associated with the reactive zone. Results: The presence of the reactive zone drastically reduced the maximum temperature reached outside it. The temperature drop was proportional to the thickness of the reactive zone: from 68?°C when it was absent to 44?°C when it is 7.5?mm thick. Higher nidus conductivity values (σ_n) implied higher temperatures, while lower temperatures meant higher σ_rz values. Changing σ_rz from 0.02?S/m to 0.087?S/m reduced lesion diameters from 2.4?cm to 1.8?cm. Conclusions: The computer results suggest that the reactive zone plays the role of insulator in terms of reducing the temperature in the surrounding area.