Imaging Findings of an Epidermoid Cyst Undergoing Malignant Transformation.

Malignant transformation of epidermoid cyst into squamous cell carcinoma (SCC) is rare. We report the case of a 39-year-old woman presenting with dizziness and cerebellar ataxia. MR scan revealed a mass in the left cerebropontine angle compressing the brainstem and the cerebellum, with two main components, a cystic and a solid one. The cystic component displayed imaging findings consistent with an epidermoid cyst. The solid component showed dense calcifications, low signal intensity on T1W, T2W and DW images and peripheral nodular enhancement. MR spectroscopy detected high lipid/lactate peaks and choline/creatine ratio. Imaging findings raised suspicion for malignant transformation, which was confirmed by histopathologic examination revealing an SCC. MR imaging with intravenous administration of gadolinium, DW images and MR spectroscopy can play a critical role in the diagnosis of malignant transformation of an epidermoid cyst.

Diffusion Tensor Imaging in brain tumors: A study on gliomas and metastases.

PURPOSE: To explore the role of Diffusion Tensor Imaging in preoperative glioma grading, as well as in differentiation between gliomas and metastatic brain tumors. We measured diffusion tensor variables in enhancement and edema regions, which were compared between the different subject groups. MATERIALS AND METHODS: We performed DTI in 48 patients (11 Low Grade Gliomas, 27 High Grade Gliomas, 10 Single Metastatic brain tumors). We measured FA, λ1, λ2, λ3, ADC, Cl, Cp, Cs, RA, and VR in enhancing portions of tumors and edema regions. Additionally, ratios of enhancement to edema values were created for each variable. RESULTS: In peritumoral edema, Cl and RA were proven to be significantly different in pair-wise comparisons, in addition to ADC, Cp, Cs and VR in enhancement regions. Enhancement to edema values were significantly different as well. CONCLUSION: Diffusion tensor indices could be used for the differentiation between low and high grade gliomas, as well as for distinction between gliomas and metastases.

Lipomatous tumors of soft tissue: MR appearance with histological correlation.

There is a broad spectrum of lipomatous tumors that involve soft tissues including ordinary lipomas, variants of lipomas, heterotopic lipomas, lipomatosis, hibernomas and liposarcomas. The recognition of these tumors is important to avoid diagnostic pitfalls. The MR imaging appearance of the lesion, including location, shape and internal architecture, suggests the diagnosis of lipomatous tumors. The signal intensity on T1-, T2-, fat-suppressed T2-weighted (FS-T2) images or short tau inversion recovery (STIR), T1- and fat-suppressed T1-weighted images after Gd-DTPA administration can be a useful aid in distinguishing between biologically different types of lipomatous tumors. The imaging features are often characteristic and reflect the histological pattern of the tumors. We present an overview of the lipomatous tumors and we correlate MR imaging appearance with histological findings.

Foci of decreased signal on T2-weighted MR images in leiomyosarcomas of soft tissue: correlation between MR and histological findings.

OBJECTIVE: Leiomyosarcomas are rare soft tissue sarcomas with varying MR signal characteristics and histologic pictures. The purpose of this study was to investigate the histological features of foci, which showed decreased signal on T2-weighted images in leiomyosarcomas of soft tissue. MATERIAL AND METHODS: We reviewed the MR images of six histologically proved cases of leiomyosarcomas of soft tissue and correlated the foci, which showed decreased signal on T2-weighted images with the histologic findings. RESULT: Microscopic examination revealed that these foci were composed of hyalinization of neoplastic tissue, internal septations, deposition of hemosiderin, or corresponded to metaplastic bone. CONCLUSION: The authors explain that the foci of decreased signal on T2-weighted MR images correspond to tissue components of the lesion, particularly fibrous tissue, hemosiderin and metaplastic bone. So, the suggestion is that leiomyosarcoma should be considered in the differential diagnosis of soft-tissue tumors that show foci of decreased signal on T2-weighted MR images.

Imaging of peripheral nerve sheath tumors with pathologic correlation: pictorial review.

Peripheral neurogenic tumors include neurilemoma, neurinoma, and malignant peripheral nerve sheath tumors. All neurogenic tumors share common imaging features. Although differentiation between them is difficult, neurogenic origin can be suggested from their imaging appearances, including fusiform shape, relation to the nerve, "split-fat" sign, associated muscle atrophy and intrinsic imaging characteristics including "target sign" as well as from lesion location along a typical nerve distribution. Our purpose is to make an overview of imaging findings of each type of peripheral nerve sheath tumor with emphasis on characteristic signs and correlate with histologic features. Morton's neuroma and intraneural ganglion are also included as tumors of nerve origin.

Ground-glass pattern fibrous dysplasia of frontal sinus.

The case of a 5-year-old boy with ground-glass pattern craniofacial fibrous dysplasia (FD) presenting with progressive swelling in the right frontal region is reported. The imaging findings with computed tomography and magnetic resonance imaging (MRI) findings are presented. The differential diagnosis with inspissated mucocele is discussed as well. Fibrous tissue could be hypo dense on CT. Post-contrast enhancement of the lesion on MRI is the key for diagnosis.

The clinical presentation of Von Meyenburg complexes.

Von Meyenburg Complexes (VMCs) is a rare clinicopathologic entity, consisting of small (<1.5cm), usually multiple and nodular cystic lesions. VMCs typically cause no symptoms or disturbances in liver function and thus in most instances they are diagnosed incidentally. We present four VMCs cases, each with a distinct clinical presentation. In two of our cases, VMCs caused mild, non-specific abdominal symptoms, including diffuse abdominal pain and discomfort. In the other two cases, in a 60-year-old woman and a 25-year-old man, the clinical presentation was implicative of an infectious hepatic process reminiscent of cholangitis and liver abscesses respectively. In each case the diagnosis was based on magnetic resonance imaging and magnetic resonance cholangiopancreatography findings showing multiple hyper-intense cystic nodules not communicating with the biliary tree. Physicians should be aware of the entire clinical spectrum of VMCs and its unique radiologic features in order to differentiate VMCs from other cystic liver lesions.

Reversible brain atrophy and subcortical high signal on MRI in a patient with anorexia nervosa.

Anorexia nervosa (AN), usually seen in young girls, is characterised by severe emaciation induced by self-imposed starvation. Enlargement of the ventricular system and sulci has been reported, as has high signal on T2-weighted images. We present a case with atrophic changes and high signal on T2-weighted images, which resolved completely following weight gain.

MRI findings of extramedullary haemopoiesis.

Extramedullary haemopoiesis (EH) is a compensatory process associated with chronic haemolytic anaemia. It is rare, however, for such an abnormality to cause spinal cord compression. We present two patients with known beta-thalassaemia intermedia who developed spinal cord compression due to masses of extramedullary haematopoietic tissue in the epidural space of the thoracic spine. The EH masses were diagnosed by MRI as an isointense epidural lesion on both T1- and T2-weighted images, compressing severely the spinal cord. After administration of a paramagnetic agent, an intermediate enhancement of the masses was evident. All the vertebral bodies had low to intermediate signal intensity as a result of displacement of fatty marrow by haematopoietic marrow. Expansion of thoracic ribs with bilateral paravertebral masses were characteristic. A small dose of radiotherapy was given and marked improvement in neurological symptoms was evident. An MRI examination established shrinkage of the mass and decompression of spinal cord. The role of MRI in diagnosis of EH masses is essential and radiation therapy is a very effective treatment for this rare complication.