Overview of Periosteal Reaction by Imaging.

The periosteum is a membrane that covers almost all bones in the body. It is a living structure but attracts little attention unless it reacts excessively. We highlight the important points in the anatomy, histology, and physiology of the periosteum, the stimuli and various aspects of periosteal reaction, and the main conditions underlying periosteal reaction.

Acute Appendicitis and Pneumatosis in a Duplicated Appendix With Schistosoma Remnants.

Appendiceal pneumatosis is rare, reported either in the context of acute appendicitis or enterocolitis. Here, we report the case of an elderly adult in whom the acute appendicitis was associated with pneumatosis and occurred in the context of a malformed appendix with pathogenic organism remnants. A 72-year-old man presented with abdominal pain 3 weeks after posttraumatic dorsolumbar surgery. The computed tomography scan showed acute appendicitis and 2 diverticula. On microscopy, the appendix showed acute appendicitis along with a Cave-Wallbridge type A duplication. In addition, several optically clear spaces were observed in the entire appendiceal wall consistent with pneumatosis of the appendix. Focally, calcified structures suggesting pathogenic organisms such as Schistosoma were noted as well. In conclusion, we report a case of appendiceal pneumatosis occurring in the context of acute appendicitis in a duplicated appendix, with presence of calcified structures suggestive of pathogenic organisms.

Nasal angioma with osseous metaplasia.

Nasal angiomas are rare. We report a case showing osseous metaplasia and discuss pathogenesis hypotheses. A 41-year-old woman presented with a right lateronasal firm, immobile mass, and interfering with glass wearing. The computed tomography scan imaging was suggestive of chondroma while the magnetic resonance imaging showed on T1-weighted images nodule isosignal, on T2-weighted images hypersignal, and intense enhancement after contrast substance injection. The lesion was surgically resected. Histological examination revealed a 0.8 cm angioma with multifocal osseous metaplasia. The diagnosis of nasal angiomas with extensive osseous metaplasia is difficult requiring microscopic examination. Conservative surgery is the treatment of choice even at an early stage due to the limited effectiveness of embolization or drugs on the osseous component.

Periosteum: characteristic imaging findings with emphasis on radiologic-pathologic comparisons.

The periosteum covers most bone structures. It has an outer fibrous layer and an inner cambial layer that exhibits osteogenic activity. The periosteum is a dynamic structure that plays a major role in bone modeling and remodeling under normal conditions. In several disorders such as infections, benign and malignant tumors, and systemic diseases, the osteogenic potential of the periosteum is stimulated and new bone is produced. The newly formed bone added onto the surface of the cortex adopts various configurations depending on the modalities and pace of bone production. Our aim here is to describe the anatomy, histology, and physiology of the periosteum and to review the various patterns of periosteal reaction with emphasis on relations between radiological and histopathological findings. A careful evaluation of the periosteal reaction and appearance of the underlying cortex, in combination with the MRI, clinical, and laboratory data, provides valuable information on lesion duration and aggressiveness, thereby assisting in the etiological diagnosis and optimizing patient management. A solid reaction strongly suggests a benign and slow-growing process that gives the bone enough time to wall off the lesion. Single lamellar reactions occur in acute and usually benign diseases. Multilamellar reactions are associated with intermediate aggressiveness and a growth rate close to the limit of the walling-off capabilities of the bone. Spiculated, interrupted, and complex combined reactions carry the worst prognosis, as they occur in the most aggressive and fast-growing diseases: the periosteum attempts to create new bone but is overwhelmed and may be breached.

Is pain duration associated with morphologic changes of osteoid osteomas at CT?

PURPOSE: To assess the morphologic changes of osteoid osteomas on computed tomographic (CT) scans in association with pain duration. MATERIALS AND METHODS: Institutional review board approval was obtained. Informed consent was waived. From January 2008 to December 2012, 235 patients were treated with interstitial laser ablation at the Hôpital Lariboisière. Ninety-six patients with histopathologically proven osteoid osteomas, complete clinical files, and CT data were studied retrospectively. The following variables were assessed: age, sex, bone location, bone segment, location of the osteoid osteoma in relation to the native cortex, nidus area, nidus calcification area and attenuation at CT, and nidus mineralization ratio (percentage of the calcification area over the total nidus area). Analysis of variance, Kaplan-Meier method, and Cox multivariate regression model were used for statistical analyses. RESULTS: The study sample consisted of 96 patients, 68 of whom were male (71%) and 28 of whom were female (29%) (ratio of male to female patients, 2.4:1). Mean age ± standard deviation was 22.2 years ± 10.4 (range, 4-54 years; median, 18.5 years). The patients' age and nidus mineralization ratio increased significantly with pain duration (hazard ratio, 0.975 [P = .031] and 0.193 [P = .007], respectively). No significant association was found between pain duration and other variables, including the nidus area. In long bones, diaphyseal osteoid osteomas were significantly less mineralized than those in other locations (P = .009). CONCLUSION: The nidus mineralization ratio of osteoid osteomas increases significantly with pain duration and may be a marker of tumor age. Diaphyseal osteoid osteomas demonstrate a lower ratio of nidus mineralization. At the onset of symptoms, older patients experience pain for a longer period before treatment.

Intratumoral gas in hepatocellular carcinoma following transarterial chemoembolization: associated factors and clinical impact.

PURPOSE: To determine the frequency and factors associated with the presence of intratumoral gas-containing areas in hepatocellular carcinoma (HCC) on computed tomography (CT) scans obtained 4-6 weeks after transarterial chemoembolization. MATERIALS AND METHODS: From June 2010 to December 2011, 201 patients underwent 286 chemoembolization procedures for HCC (n = 497 tumors) and were retrospectively included. The presence of intratumoral gas was assessed on CT 4-6 weeks after chemoembolization. Clinical and biologic data and tumoral and chemoembolization procedure characteristics were noted. Factors associated with the presence of intratumoral gas were evaluated. Tumor response was assessed by using European Society for the Study of the Liver criteria. Tumors containing gas or not containing gas were compared by univariate and multivariate analysis. RESULTS: Intratumoral gas was found in 26 tumors (5%) after 26 chemoembolization procedures (9.1%) in 26 patients (13%). Gas was related to abscess formation in three patients (11.5%). On multivariate analysis, a large mean tumor diameter at baseline (72.4 mm vs 40.2 mm; P = .003), chemoembolization with drug-eluting beads (P = .033), and superselective approach (P = .024) were independently associated with the presence of gas. Tumors that exhibited gas-containing areas at 1 month had a significantly higher objective response rate than those that did not (P < .0001). CONCLUSIONS: Intratumoral gas-containing areas after chemoembolization are rarely related to the formation of abscesses. The presence of intratumoral gas on CT 4-6 weeks after chemoembolization could be a surrogate marker for marked tumor necrosis.