Low-grade intraosseous osteosarcoma with prominent lymphoid infiltrate.

Low-grade intraosseous osteosarcoma is an uncommon and well-differentiated osteosarcoma with a good prognosis. We report a proximal tibial low-grade intraosseous osteosarcoma with a prominent intratumoral lymphoid infiltrate, which led to an initial diagnosis of probable malignant lymphoma. The importance of this infiltrate, which exhibited reactive features on flow cytometric studies, is not known.

Malignant chondroblastoma presenting as a recurrent pelvic tumor with DNA aneuploidy and p53 mutation as supportive evidence of malignancy.

We report a rare case of malignant chondroblastoma, which presented in a 47-year-old man as a recurrent tumor, 18 years following wide excision of a typical pelvic chondroblastoma. Radiologic studies of the recurrent tumor showed a large, lytic, destructive lesion of the right pelvic bones and femur, with a pathologic fracture of the latter, a large pelvic soft tissue mass, and multiple pulmonary metastases. Biopsy tissue showed typical features of chondroblastoma, but also increased nuclear atypia, hyperchromasia, and pleomorphism, compared to the original tumor, and, most significantly, abnormal mitotic figures.

Lesions of the bones of the hands and feet.

Neoplasms and their simulators in the bones of the hands and feet include the majority of those found in other skeletal sites, and a disproportionate number of some. We examined the clinical, radiologic, and pathologic features of 240 lesions of the hand and foot bones. Benign tumors and lesions including reactive and reparative conditions comprised 203 cases.

Effect of erionite on the pleural mesothelium of the Fischer 344 rat.

Objective: This study sought to assess the fibrogenic and carcinogenic potential of erionite (a fibrous zeolite) on the pleural mesothelium of the Fischer 344 rat (n = 24).

Design: The study was designed to examine rat pleural mesothelial changes by three independent observers at timed intervals, ranging from 1 to 480 days postinoculation using erionite from the Pine Valley, Nevada (USA) area. The mean length and width of the erionite fibers were 2.

Effect of fibrous glass on rat pleural mesothelium. Histopathologic observations.

Female Fisher 344 rats (n = 25) were inoculated intrapleurally with a single 20-mg dose of (JM-100) fibrous glass. The mean length (2.2 microns) and width (0.