Malignant uveal melanoma and simulating lesions: MR imaging evaluation

Twenty-one patients with intraocular disease were studied by magnetic resonance (MR) imaging and computed tomography (CT). In 13 cases, malignant uveal melanoma was considered the likely diagnosis. Both imaging methods were accurate in determining the location and size of uveal melanomas. MR imaging was superior for the assessment of possible associated retinal detachment, for assessment of vitreous change, and for differentiating uveal melanoma from choroidal hemangioma and choroidal detachment. A case of retinal gliosis could not be differentiated from uveal melanoma by either technique. Uveal melanomas appeared as hyperintense lesions on T1-weighted images and as hypointense lesions on T2-weighted images. High signal intensity of the vitreous was observed in patients with vitritis and in those who were thought to have protein leaking into the vitreous as a result of impairment of the retinal-blood barrier.     

Acute renal rejection versus acute tubular necrosis in a canine model: MR evaluation

Findings of magnetic resonance (MR) imaging in acute renal rejection and acute tubular necrosis (ATN) were studied in dogs. On T1-weighted images, corticomedullary differentiation was absent in kidneys undergoing acute rejection. The loss of corticomedullary differentiation in these kidneys was secondary to a decrease in the relative signal intensity of the cortex, indicating prolongation of the T1 relaxation time of the cortex. In contrast, corticomedullary differentiation was preserved on T1-weighted images of autotransplanted kidneys and kidneys with ATN. MR imaging findings correlated with changes in water content in these three groups of kidneys. Kidneys undergoing acute rejection showed a marked increase in water content compared with kidneys in the other two groups. No change in fat content was found in any group.     

Acute demyelinating sensorimotor polyneuropathy in B‐cell lymphoma with IGM autoantibodies against glycolipid GD1B

A 20‐year‐old man developed weakness without sensory complaints ten days after rubella. Examination showed limb weakness and brisk tendon reflexes but no sensory abnormalities. Laboratory investigations revealed IgG and IgM anti‐Rubella and increased CSF protein content (0,8 g/L). Electrophysiological examination showed partial motor conduction blocks in eight nerves and normal sensory conductions even across the sites of CB. Brain and spinal cord MRI and SEPs were normal. The patient was treated with four plasmaphereses and fully recovered in six months. Conduction blocks gradually improved with increasing duration and abnormal temporal dispersion in proximal CMAPs. GBS has been rarely reported after rubella. Anti‐myelin basic protein antibodies have been found in a patient with a relapsing motor neuropathy following rubella vaccination. As antibodies cross‐reacted with a viral protein, molecular mimicry has been proposed as a pathophysiological mechanism. In our patient we did not find anti‐MBP antibodies and antibodies to‐glycolipids (GM1, GM2, GA1, GD1a, GD1b, GQ1b, sulfatides, galactocerebroside) were also negative. Indirect immunofluorescence after incubation of patient's serum on rabbit sciatic nerve and human sural nerve and roots was negative. Our patient confirms the occurrence of GBS following Rubella and shows some uncommon features: 1) hyperactive deep tendon reflexes; 2) demyelination selectively involving motor fibres; and 3) widespread early conduction blocks in intermediate nerve segments.