Myxoid liposarcoma of the retropatellar fat pad.

Soft-tissue sarcomas are rare lesions, and they are occasionally seen by the orthopedic surgeon. We describe the clinical history of a patient with a myxoid liposarcoma that arose from the retropatellar fat pad of the knee. The differential diagnosis of knee masses and the magnetic resonance image characteristics of myxoid liposarcoma are discussed. There are no previous reports of liposarcomas originating from the retropatellar fat pad. Given the consequences of inappropriate biopsy and surgery of suspected benign lesions, it is fundamentally important to adhere to the principles of musculoskeletal oncology in the evaluation of any soft-tissue mass that could be malignant.

In vitro effects of Nd:YAG laser radiation on blood: a quantitative and morphologic analysis.

Use of the Neodymium: yttrium -aluminum -garnet (Nd:YAG) laser to recanalize stenosed arteries may require delivery of the beam through blood. To assess the degree of hemolysis and debris formation, 54 samples of citrated whole blood were exposed to Nd:YAG laser radiation of varying powers (10, 20 and 30 watts) and duration (1, 2.5 and 5 seconds). Compared to control samples which were not subjected to laser light, there was no significant decrease in hematocrit (41 to 40.5 +/- 5%), hemoglobin concentration (13.8 to 13.8 +/- .06 g/1OO ml), or increase in "free" hemoglobin concentration. Debris weight (from .45 +/- .002 to .45 +/- .002 mg), as well as the white blood cell count, was also not significantly changed (from 5,400 to 5,200 +/- 240 WBC/cm). Light microscopy examination of debris from samples of whole blood, washed erythrocytes, and platelet-rich plasma subjected to the laser at 30 watts for five seconds failed to demonstrate the presence of membrane denaturation of blood elements, as compared with the morphologic changes observed in whole blood samples exposed to a "hot tip" rather than Nd:YAG laser radiation. Nd:YAG laser can be used intravascularly without fear of hemolysis or debris "micro-embolization" up to a power of 30 watts for five seconds.

A hitherto undescribed cause of prosthetic mitral valve obstruction.

A case is described in which severe prosthetic mitral valve obstruction was produced by entanglement of sutures across the central axis of the prosthesis on its ventricular side. The entangled sutures prevented the tilting disc occluder from falling into the left ventricular cavity during ventricular diastole.