The entheses: histology, pathology, and pathophysiology.

The entheses are the sites of attachment of ligaments, tendons, and joint capsules to bone. Their ubiquitous distribution throughout the body explains the considerable clinical and radiological polymorphism of entheseal diseases. In addition to aging and mechanical factors, many disorders related to a vast array of pathophysiological mechanisms can produce entheseal disease. The spondyloarthropathies provide the most striking examples of entheseal involvement in inflammatory joint disease. Over the last few decades, major advances have shed light on the biochemical composition of the entheses, their histological features, their mechanical role, and their evaluation by ultrasonography and magnetic resonance imaging. These new insights have generated valuable hypotheses about the pathogenesis of spondyloarthropathies.

Aberrant axon neurofilaments in schwannomas associated with phacomatoses.

Neurofibromas and schwannomas express S100 protein, while axon filaments are not commonly found in schwannomas. Histopathological distinction between neurofibromas and schwannomas is usually easy, except for some variants. To assess the reliability of immunohistochemistry results for the differential diagnosis of the latter, 46 neural tumors of the skin were studied: 31 schwannomas [12 schwannomatosis, 7 neurofibromatosis type 2 (NF2)-associated, 12 solitary] and 15 plexiform neurofibromas associated with neurofibromatosis type 1. All tumors were subjected to immunohistochemical-labeling studies with antibodies to S100 protein and axon-specific neurofilament proteins. All tumors were positive with anti-S100 protein antibody. Schwannomas were strongly and diffusely positive while neurofibromas displayed more varied and limited S100 protein reactivity. Axon filaments were detected in 15 of 15 plexiform neurofibromas and 7 of 19 schwannomas associated with NF2/schwannomatosis. None of the 12 solitary schwannomas reacted with anti-axon neurofilament antibodies. Aberrant axons were observed in the schwannomas associated with NF2/schwannomatosis but not in the solitary schwannomas. Therefore, when there are multiple neural tumors, immunohistochemical visualization of axons may be misleading if it is not related to the clinical context and the standard histological features.

Colic metastases of alveolar soft-part sarcoma: a case report and review of the literature.

Alveolar soft-part sarcoma is a rare soft tissue malignant tumor that commonly arises in skeletal muscles or musculofascial planes in children and young adults. Metastases of lung, brain, and bone are often present at the time of diagnosis or appear late in the course of disease. We present the first case, to our knowledge, of colic metastases in a 43-year-old woman who had a leg primary tumor more than 15 years ago and multiple lung and brain metastases. The treatment of these two caecal metastases, revealed by an anemia, consisted in laparoscopic right colectomy.

Magnetic resonance imaging for the diagnosis of stress fractures in a horse.

In humans, magnetic resonance (MR) imaging is the method of choice for the diagnosis of stress fractures. In this paper, bilateral stress fracture of the lateral condyle of the third metacarpal bone in a French trotter is described. Results of the radiographic, MR imaging, and histologic examinations are presented, with a focus on the MR signal abnormalities found. Based on this patient, the potential use of MR imaging for the diagnosis of stress fractures in horses is discussed.