The differentiation between glioblastoma multiforme (GBM) and primary cerebral lymphoma (PCL) is important because the treatments are substantially different. The purpose of this article is to describe the MR imaging characteristics of GBM and PCL with emphasis on the quantitative ADC analysis in the tumor necrosis, the most strongly-enhanced tumor area, and the peritumoral edema. This retrospective cohort study collected 104 GBM (WHO grade IV) patients and 22 immune-competent PCL (diffuse large B cell lymphoma) patients. All these patients had pretreatment brain MR DWI and ADC imaging. Analysis of conventional MR imaging and quantitative ADC measurement including the tumor necrosis (ADCn), the most strongly-enhanced tumor area (ADCt), and the peritumoral edema (ADCe) were done. ROC analysis with optimal cut-off values and area-under-the ROC curve (AUC) was performed. For conventional MR imaging, there are statistical differences in tumor size, tumor location, tumor margin, and the presence of tumor necrosis between GBM and PCL. Quantitative ADC analysis shows that GBM tended to have significantly (P<0.05) higher ADC in the most strongly-enhanced area (ADCt) and lower ADC in the peritumoral edema (ADCe) as compared with PCL. Excellent AUC (0.94) with optimal sensitivity of 90% and specificity of 86% for differentiating between GBM and PCL was obtained by combination of ADC in the tumor necrosis (ADCn), the most strongly-enhanced tumor area (ADCt), and the peritumoral edema (ADCe). Besides, there are positive ADC gradients in the peritumoral edema in a subset of GBMs but not in the PCLs. Quantitative ADC analysis in these three areas can thus be implemented to improve diagnostic accuracy for these two brain tumor types. The histological correlation of the ADC difference deserves further investigation.

We present a case of spontaneous mediastinal and subcutaneous cervical emphysema due to perforation of an occult sigmoid diverticulitis.Mediastinal emphysema should alert the physician to the possibility of retroperitoneal gastrointestinal perforation, even in patients without signs of distinct peritoneal irritation. Eur Respir J., 1995, 8, 2188-2190. Eur Respir J, 1995. 8, 2188-2190 DOI: 10.1183 Spontaneous supraclavicular emphysema is relatively common as a sequela of pulmonary interstitial emphysema and pneumomediastinum. It is often the result of alveolar wall rupture secondary to high intra-alveolar pressure caused by artificial ventilation, coughing, and straining [1]. However, it is quite rarely associated with intestinal perforation, particularly in cases with no history of instrumental manipulation of the hollow abdominal viscera [2]. Case reportA 67 year old woman was referred to our emergency service because of sudden onset of marked neck swelling for 2 h without concomitant dyspnoea. This was preceded by a slight lower back soreness for about 1 week. She had visited our orthopaedic clinic 3 days before, where degenerative disc disease with compression fracture of L4-5 was disclosed after radiographic imaging of the spine. The patient had previously been in good health, with the exception of diabetes mellitus, which had not been satisfactorily controlled.On physical examination, the patient appeared slightly ill-looking with a temperature of 36.4% blood pressure of 160/90 mmHg, pulse rate of 84 beats·min -1 , and respiratory rate of 16 breaths·min -1 . The patient's neck demonstrated swelling and crepitation, but no significant lymphadenopathy was found. Chest examination was normal. The abdomen was slightly distended and vaguely tender over the lower region, without signs of peritoneal irritation. Peristalsis remained active and bowel function was normal. However, knocking pain over both loins seemed equivocal. A chest roentgenogram demonstrated an unexpected pneumomediastinum, but no free air was apparent in the abdomen ( fig. 1).Complete blood count (CBC) showed a haemoglobin level of 141 g·L -1 , a white blood cell count (WBC) of 20.6×10 9 cells·L -1 and a platelet count of 218×10 9 ·L -1 . The faeces were positive (+++) for occult blood. Blood sugar level was 3.6 g·L -1 (normal range 0.7-1.1 g·L -1 ), and alkaline phosphatase was 147 U·L -1 (normal range 25-80 U·L -1 ). Fibreoptic bronchoscopic examination produced no evidence of pulmonary disruption. Gastroduodenoscopy was also performed, which revealed only multiple small gastric ulcers at the antrum, primarily along the side of greater curvature, and still with no sign of perforation. After 5 days of intravenous antibiotics and oral hypoglycaemic treatment, the WBC and glucose level returned to normal ranges.

This case subject is a 1-year-old girl presenting with recurrent diffuse soft-tissue swelling of the scalp and periorbital region. Her family denied any known history of trauma. There was no obvious discoloration or local heat at the lesion. Magnetic resonance imaging (MRI) revealed diffuse soft tissue swelling of the scalp manifesting as high signal intensity on T2-weighted images and low signal intensity on T1-weighted images with diffuse enhancement after gadolinium-contrast administration. Biopsy yielded inconclusive pathological results. Fibrodysplasia ossificans progressiva (FOP) was not suspected until malformation of the patient's toes was noticed. The scalp lesion underwent spontaneous regression, and subsequent radiographs of the chest and cervical spine revealed heterotopic ossifications of the neck and thorax. Early diagnosis of FOP is vital because trauma, unnecessary biopsy and intramuscular injection are known to cause acceleration of heterotopic ossifications. Previous studies reported diffuse soft tissue swelling at the posterior neck, thoracic wall or paraspinal region as preosseous lesions of FOP (Shiva Kumar et al. Neurology. 2010;74(6):e20, Merchant et al. Pediatr Radiol. 2006;36(10):1108-11, Hagiwara et al. AJR Am J Roentgenol. 2003;181(4):1145-7). To our knowledge, diffuse soft tissue swelling of the scalp as a preosseous lesion of FOP and associated MRI findings have not yet been reported. We believe that awareness of preosseous lesions presenting as diffuse soft tissue swelling, in addition to shortening and valgus deformity of the great toes, is an important diagnostic clue for establishing FOP.

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