CT Findings of Primary Thy roid Lymphoma: Report of Two Cases

We describe two cases of primary thyroid lymphoma, involving 64-and 74-year-old women who presented with arapidly growing palpable mass in the anterior neck. In both patients, plain radiographs of this region re-vealedtracheal displacement and soft tissue mass, and CT scans demonstrated the presence of a large soft tis-sue masswith homogeneously low attenuation, predominantly located in the unilateral lobe of the thyroid g-land. Within themasses there was no calcification, necrosis, or hemorrhage, though in one patient the trachea was involvedposteriorly by the mass Both masses appeared as cold nodules on RI scan, and in both patients, the final diagnosiswas diffuse large cell type non-Hodgkin's lymphoma with a background of Hashimoto's thyroiditis.

Bone Signal Abnormality, as seen on Knee Joint MRI: Relationship between Its Location and Associated Injury

PURPOSE: The purpose of the study was to evaluate the relationship between the location of bone signalabnormality and associated injury, as seen on MR, in patients with acute knee joint injury. MATERIALS AND METHODS: Thirty-six patients with acute knee injury and bone signal abnormalities on MR were included in this study. Thefemur and tibia were each divided into six compartments, namely the anteromedial, medial, posteromedial,anterolateral, lateral, and posterolateral ; these were obtained in each knee joint. We evaluated the location ofbone signal abnormality and the corresponding arthroscopic or operative findings of injury to ligaments andmenisci. Cases with signal abnormalities involving more than three compartments were excluded. RESULT: Bonesignal abnormalities were demonstrated in 51 compartments. Most(84%, 43/51) were noted in the lateral half of theknee joint, the most common location being the tibio- posterolateral compartment(13/51). The femoro-lateral(11/51) and tibio- anterolateral compartment(8/51) were the next most common locations. All cases(13/13)with bone signal abnormality in the tibio- posterolateral compartment had tears at the anterior cruciate ligament,while 9 of 11 cases(81%) with abnormality in the femoro- lateral compartment had tears at the anterior cruciateligament. Six of eight cases(75%) with signal abnormality in the tibio- anterolateral compartment had tears at theposterior cruciate ligament ; 31 of 43 cases (72%) with abnormality in the lateral half of the knee joint hadtears at the medial collateral ligament. Six of eight cases(75%) with signal abnormality in the medial half of theknee joint had tears at the medial meniscus, but no lateral meniscal tear was found. Among patients with signalabnormality in the lateral half of the knee joint, the tear was lateral meniscal in nine of 43 cases(21%) andmedial meniscal in six of 43(14%). CONCLUSION: The location of bone signal abnormality, as seen on knee MR, inpatients with acute knee joint injury could be an important finding suggesting associated injury.

MRI Findings of Hemangioblastomas

PURPOSE: The purpose of this study is to evaluate the findings of magnetic resonance imaging(MRI) of posterior fossa hemangioblastoma and usefulness of contrast enhancement with Gd-DTPA. MATERIALS AND METHODS: Seven patients with posterior fossa hemangioblastoma were studied with both pre- and post-enhanced MRI. The MR images were reviewed regarding the location, size, signal intensities of cysts and mural nodules, and their contrast enhancement pattern. RESULTS: Five tumors were located in cerebellar hemisphere, one in vermis, and one in posterior part of medulla. One patient with von HippeI-Lindau disease had a medullary hemangioblastoma with multiple pancreatic cysts. In 6 cases, the major portion of the tumor was cysts and had small mulkal nodules. The solid portion was relatiely lange in one case, cemprising half of the tumor Cysts were oval shaped and their sizes were 3--6.7cm in diameter. In five cases(71%), septations were noted within the cysts. Cysts were isointense or slightly hyperintense on Tl-weighted image and hyperintense on T2-weighted image compared with cerebrospinal fluid. Mural nodules were oval or rounded appearance in five cases and flattened appearance in two, and their size was 0.5--2.5cm in diameter. Mural nodules were isointense to gray matter. They were detected in five cases on Tl-weighted images and one case on T2-weighted images. In two cases, vascular signal void area was noted in mural nodules. On contrast-enhanced Tl-weighted images, all mural nodules were intensely enhanced. CONCLUSION: MRI proved to be a good diagnostic method to detect and characterize posterior fossa hemangioblastoma. The most common finding is Cystic posterior fossa lesion with enhancing mural nodule. Contrast enhancement is essential for specific diagnosis.