Synovial plicae are normal anatomic structures of the knee that sometimes become symptomatic. Magnetic resonance (MR) imaging and MR arthrography are useful tools in the evaluation of synovial plicae and allow differentiation of these entities from other causes of knee pain. At MR imaging, synovial plicae appear as bands of low signal intensity within the high-signal-intensity joint fluid. Gradient-echo T2-weighted and fat-suppressed T2-weighted or proton density-weighted MR images are optimal for the evaluation of plicae. Plica syndrome, the painful impairment of knee function in which the only finding that helps explain the symptoms is the presence of a thickened and fibrotic plica, should be included in the differential diagnosis of internal derangement of the knee. A diffusely thickened synovial plica, perhaps associated with synovitis or erosion of the articular cartilage of the patella or femoral condyle, in a patient with no other significant MR imaging findings suggests the diagnosis of plica syndrome. Once the diagnosis has been made, nonsurgical treatment is preferable initially. Failure of the patient to improve with conservative treatment leaves arthroscopic excision of the pathologic plica as the treatment of choice.

The os centrale carpi is one of the accessory ossicles that have been described in the carpus. We report on the imaging findings of a rare case of unilateral osteonecrosis in a patient with bilateral os centrale carpi. The differential diagnosis of this entity and the suggested etiology for the development of osteonecrosis are discussed.

The authors report a case of cystic choroid plexus papilloma that originated in the posterior fossa. No connection with the ventricular system was found intraoperatively. Magnetic resonance (MR) and computerized tomography imaging did not furnish a diagnosis, but findings of pathological examinations were consistent with those of choroid plexus papilloma. The authors describe the different appearances of the tumor on MR images and discuss the differential diagnosis with other tumors of the posterior fossa.

Primary signet-ring cell adenocarcinoma of the cervix is very rare and less common than metastatic signet-ring cell adenocarcinoma. To the best of the authors' knowledge only one genuine case has been reported to date. Tvvo cases of primary signetring cell adenocarcinoma of the uterine cervix in patients aged 68 and 74 years are presented. The tumors were in stage IB. The light microscopic findings were confirmed by histochemical and immunohistochemical study. DNA nuclear analysis by flow cytometry of the neoplasms revealed an aneuploid (tetraploid) pattern. The patients had no evidence of recurrent or metastatic disease 35 and 25 months after a radical hysterectomy with bilateral salpingo-oophorectomy and lymph node dissection respectively. Primary signet-ring cell adenocarcinoma of the cervix should be differentiated from metastatic adenocarcinoma, endocervical involvement by signetring cell carcinoma of the endometrium, benign mucin-filled signet-ring cell aggregates that may accumulate in mucosal folds, microglandular hyperplasia, mucicarminophilic histiocytosis, and other malignant neoplasms that may have signet ring-like cells and deserve consideration such as squamous cell carcinoma, malignant lymphoma, myeloma, and malignant melanoma. Although very rare, signetring cell adenocarcinoma of the cervix can exist as a primary tumor. Distinction between a primary neoplasm and a metastasis to the cervix is decisive for treatment and prognosis. Int J Surg Pathol 5(3/4): [95][96][97][98][99][100] 1997 Adenocarcinomas of the uterine cervix at present account for from 10% to 20% of invasive carcinomas of the cervix in developed countries [1,2]. This apparent increased frequency of adenocarcinomas results from a decrease in the incidence of the invasive squamous cell carcinoma and a real absolute increment of the glandular tumors [3]. Although less common than squamous cell carcinomas, adenocarcinomas are far more difficult to diagnose in the

Magnetic resonance urography (MRU) can be performed on the basis of two different imaging strategies: static-fluid MRU, based on heavily T2 weighted turbo spin echo (TSE) sequences, and gadolinium-enhanced excretory MRU. Both MR urographic techniques in combination with standard MRI permit a comprehensive examination of the entire urinary tract. This pictorial review illustrates the MRU features of the a wide spectrum of pathological conditions affecting the urinary tract.