Homogeneous myxoid liposarcomas mimicking cysts on MRI: A challenging diagnosis.

OBJECTIVES: Myxoid liposarcoma (M-LPS) is the second most frequent subtype of liposarcoma. Foci of fat on MRI are strongly suggestive of this diagnosis. The aims of this study are to (i) assess the prevalence of perfectly homogeneous M-LPS-mimicking cyst and characterize their associated clinical and pathological features and to (ii) identify helpful clues to prevent misdiagnosis when encountered with a cyst-like lesion in soft tissue parts. METHODS: MR images from 32 consecutive pathologically proven M-LPS and round cell liposarcomas (RC-LPS) were retrospectively reviewed independently by two radiologists at our institution. Location, morphology, signals, lesion architecture, heterogeneity, margins and periphery were systematically assessed in each case. Medical records were checked for initial and definitive histopathological diagnosis, therapeutic managements and outcomes. Histopathological specimens of cyst-like M-LPS were reviewed for the study. RESULTS: We have identified seven perfectly homogeneous well-defined cyst mimickers (21.9%) located on the limbs, all but one being deep-seated. These tumors were significantly smaller than the conventional M-LPS (p = 0.0005). Six lesions were initially diagnosed as benign; 4 patients underwent marginal surgical resection without prior diagnosis and 2 cases were put under medical surveillance, one of which progressed towards classical RC-LPS on follow-up MRI. No specific pathological features could be identified nor were any clinical adverse outcomes recorded. CONCLUSION: "Cyst" on MRI, without pathological adjacent joint, necessitates ultrasonography with Doppler and intravenous Gadolinium agent injections as subsets of M-LPS can mimic cyst on MRI. Cyst-like M-LPS, due to their smaller size and relative favorable outcome, could have better prognosis.

Soft tissue masses with myxoid stroma: Can conventional magnetic resonance imaging differentiate benign from malignant tumors?

OBJECTIVES: To retrospectively evaluate the diagnostic performance of morphological signs observed on conventional magnetic resonance (MR) imaging to differentiate benign from malignant peripheral solid tumors of soft tissue with myxoid stroma. METHODS: MR images from 95 consecutive histopathologically proven tumors (26 benign and 69 malignant) of soft tissues with myxoid components were evaluated in our tertiary referral center. Two radiologists, blind to pathology results, independently reviewed conventional MR sequences including at least a) one T2-weighted sequence with or without fat suppression; b) one T1-weighted sequence without fat suppression; and c) one T1-weighted sequence with gadolinium-complex contrast enhancement and fat suppression. Multiple criteria were defined to analyze morphology, margins, architecture and tumor periphery and evaluated for each lesion. Intra- and inter-observer reproducibility and Odds ratios were calculated for each criterion. RESULTS: The most relevant and reproducible criteria to significantly predict malignancy were: (1) ill-defined tumor margins, (2) a hemorrhagic component, (3) intra-tumoral fat, (4) fibrosis and (5) the "tail sign". A lesion is classified as malignant if any of these 5 criteria is present, and benign if none of them are observed. Therefore, this combination provides a sensitivity of 92.9% and a specificity of 93.3%. CONCLUSION: Conventional MR imaging provides reproducible criteria that can be combined to differentiate between benign and malignant solid tumors of soft tissue with myxoid stroma.

Cervical Spinal Cord DTI Is Improved by Reduced FOV with Specific Balance between the Number of Diffusion Gradient Directions and Averages.

BACKGROUND AND PURPOSE: Reduced-FOV DTI is promising for exploring the cervical spinal cord, but the optimal set of parameters needs to be clarified. We hypothesized that the number of excitations should be favored over the number of diffusion gradient directions regarding the strong orientation of the cord in a single rostrocaudal axis. MATERIALS AND METHODS: Fifteen healthy individuals underwent cervical spinal cord MR imaging at 3T, including an anatomic 3D-Multi-Echo Recombined Gradient Echo, high-resolution full-FOV DTI with a NEX of 3 and 20 diffusion gradient directions and 5 sets of reduced-FOV DTIs differently balanced in terms of NEX/number of diffusion gradient directions: (NEX/number of diffusion gradient directions = 3/20, 5/16, 7/12, 9/9, and 12/6). Each DTI sequence lasted 4 minutes 30 seconds, an acceptable duration, to cover C1-C4 in the axial plane. Fractional anisotropy maps and tractograms were reconstructed. Qualitatively, 2 radiologists rated the DTI sets blinded to the sequence. Quantitatively, we compared distortions, SNR, variance of fractional anisotropy values, and numbers of detected fibers. RESULTS: Qualitatively, reduced-FOV DTI sequences with a NEX of ≥5 were significantly better rated than the full-FOV DTI and the reduced-FOV DTI with low NEX (N = 3) and a high number of diffusion gradient directions (D = 20). Quantitatively, the best trade-off was reached by the reduced-FOV DTI with a NEX of 9 and 9 diffusion gradient directions, which provided significantly fewer artifacts, higher SNR on trace at b = 750 s/mm2 and an increased number of fibers tracked while maintaining similar fractional anisotropy values and dispersion. CONCLUSIONS: Optimized reduced-FOV DTI improves spinal cord imaging. The best compromise was obtained with a NEX of 9 and 9 diffusion gradient directions, which emphasizes the need for increasing the NEX at the expense of the number of diffusion gradient directions for spinal cord DTI contrary to brain DTI.

[Septic shock with multiple organ failure after returning from Southeast Asia]. / Choc septique avec défaillance multiviscérale au retour d'Asie du Sud-Est.

For a patient recently returned from a tropical country in intensive care, the leading hypothesis for a fever leading to multiple organ failure is evidently malaria. Nonetheless, many other causes are possible and should be considered: parasites, viruses, and bacteria. A multidisciplinary discussion between specialists in emergency medicine, radiology, pathology, and infectious diseases is essential to start appropriate treatment as quickly as possible without impairing the patient's prognosis.

Steatotic hepatocellular adenomas with different phenotypic subtypes: a case report.

Hepatocellular adenomas (HCAs) are heterogeneous group of benign tumors; three pathomolecular subtypes have been identified so far: hepatocyte nuclear factor 1 α-inactivated HCA (H-HCA) (35-40%), inflammatory HCA (I-HCA) (>50%), ß-catenin activated HCA (10%). Ten percent of I-HCA are also ß-catenin activated. We report a rare case of three histologically confirmed steatotic HCAs of three different phenotypes: I-HCA, ß-catenin activated I-HCA, and H-HCA in a 36-year-old woman. This observation outlines that in the same patient, HCA may be of different subtypes. The predisposition to develop different HCA hypothetically caused by a "benign tumorigenic field effect" may result, even rarely, in different genotypes/phenotypes such as H-HCA and I-HCA. Moreover, we illustrate the very high specificity of MR for subtyping HCA.

Hepar lobatum carcinomatosum associated with liver metastases from breast cancer: report of five cases.

BACKGROUNDS AND AIMS: Hepar lobatum carcinomatosum (HLC) is an exceptional acquired hepatic distortion which consists in irregularly lobulated hepatic contours seen in patients with known liver metastases, usually from breast carcinoma. We aimed to describe and analyze five similar cases of HLC resulting from metastatic mammary carcinoma in the liver and associated with rapid hepatic failure. METHODS: Five cases of HLC were investigated. Medical (including blood liver tests), radiological and histological data (2 cases) were collected and retrospectively analyzed. All patients were followed up for metastatic invasive ductal carcinoma of the breast and had a common pattern of treatment with combination of targeted therapies (bevacizumab, AVASTIN) and chemotherapy (paclitaxel, TAXOL). RESULTS: All the patients showed rapid hepatic failure after a mean of 9 courses of bevacizumab/paclitaxel. In all cases, liver imaging revealed liver capsule retraction and an irregular lobular margin. An apparent tumor regression of all liver metastases was showed in two cases. Biopsies were consistent with sinusoidal obstruction syndrome (SOS) and, surprisingly, no tumoral cells were found. CONCLUSION: Although rare, such an unusual pattern of liver metastasis may mimick acute cirrhosis and cause rapid hepatic failure in patients, despite possible apparent tumor regression on imaging. The etiology of this pathology is unclear, and may involve multiple pathogenic factors. Direct or indirect vascular injury plays an important role in the development of HLC.

[An ophthalmologic diagnostic error leading to a rare systemic diagnosis: Erdheim-Chester disease]. / Une errance diagnostique ophtalmologique aboutissant à un diagnostic systémique rare: la maladie d'Erdheim-Chester.

INTRODUCTION: Erdheim-Chester disease is a rare systemic disease. The diagnosis is difficult due to significant clinical and morphological polymorphism. Orbital involvement is rare, but constitutes a classic means of detection. OBSERVATION: We report the case of a 60-year-old man, who consulted for evaluation of bilateral retro-orbital tumors. These tumors had been discovered on head CT two years previously during work-up of proptosis. Two biopsies were performed. The first one revealed polymorphous inflammatory tissue. The second one revealed intense granulomatous reaction, rich in non-specific foamy histiocytes. Thoracic-abdominal-pelvic CT scan detected peri-aortic and retroperitoneal infiltration. The association of these signs pointed to a diagnosis of Erdheim-Chester disease, confirmed by the re-examination of the histological samples. DISCUSSION: Erdheim-Chester disease is a rare non-Langerhans histiocytosis with a specific tropism for perivascular and fatty connective tissue. The cause is not known. The diagnosis of this systemic disease is histological. CONCLUSION: In the case of bilateral intra-orbital tumors, the diagnosis of Erdheim-Chester disease must be considered.

Pulmonary aspergilloma in a cavity formed after percutaneous radiofrequency ablation.

We report two cases of pulmonary aspergilloma (PA) in a cavity formed after percutaneous radiofrequency ablation (PRFA), a rare complication that has only been described once in the literature. The first patient was a 59-year-old white woman treated for a secondary lung nodule of an advanced hepatocellular carcinoma. One month after PRFA, a consolidation of a cavity was noticed with an "air crescent sign," and aspergilloma serology was highly positive. A bisegmentectomy was performed due to the proximity of the lesion to mediastinal vessels and the absence of significant regression after antifungal treatment. Histological examination confirmed the diagnosis of PA. The second patient was a 61-year-old white man followed-up for a non-small-cell lung cancer. A cavitation with thick margins in the ablation zone was noticed 6 months after PRFA. A biopsy was performed, and aspergilloma was diagnosed. Medical treatment with itraconazole was administered for 13 months, and there was significant regression.

Interest of contrast-enhanced sonography to identify focal nodular hyperplasia with sinusoidal dilatation.

BACKGROUND AND AIMS: Focal nodular hyperplasia with major sinusoidal dilatation (FNH-sd) is a misleading entity, with some features resembling inflammatory hepatocellular adenoma (HCA). We aimed to assess the performance of contrast-enhanced ultrasound (CEUS) for the diagnosis of FNH-sd. METHODS: Four histologically proven FNH-sd nodules in four patients were investigated with both MRI and CEUS imaging. Sinusoidal dilatation was focally visible in all cases in histology. RESULTS: In MRI, in all the four cases, lesions were hypervascular in arterial phase, with high intensity in T2-weighted sequence imaging and persistent enhancement in the delayed gadolinium-enhanced phase. These MRI features were more indicative of HCA than FNH. On the other hand, CEUS showed a very specific centrifugal filling followed by a strong, homogeneous enhancement of the whole lesion. CONCLUSION: CEUS seems to be an essential step for the diagnosis of non-typical FNH, such as FNH-sd. This small series highlights the interest of performing both CEUS and MRI for the diagnosis of atypical focal liver lesions, such as FNH-sd.