rhesus cytomegalovirus (macacine herpesvirus 3)-associated facial neuritis in simian immunodeficiency virus-infected rhesus macaques (Macaca mulatta).

Peripheral neuropathies are common sequelae to human immunodeficiency virus (HIV) infection in humans and are due to a variety of mechanisms, including direct antiretroviral toxicity, HIV-mediated damage, immune-mediated disorders, and opportunistic viral infections. Rhesus macaques (Macaca mulatta) infected with simian immunodeficiency virus (SIV) remain the most consistent animal model for unraveling the pathogenesis of lentiviral-associated disease and its associated opportunistic infections. Rhesus cytomegalovirus (RhCMV) is the most common opportunistic viral infection in rhesus macaques infected with SIV and causes multiorgan pathology; however, its role in peripheral nerve pathology has not been explored. We have identified 115 coinfected cases with SIV and RhCMV, of which 10 cases of RhCMV-associated facial neuritis were found (8.7% prevalence). Histologic lesions were consistent in all cases and ranged from partial to complete obliteration of the nerves of the tongue, lacrimal gland, and other facial tissues with a mixed inflammatory population of neutrophils and macrophages, of which the latter commonly contained intranuclear inclusion bodies. Luxol fast blue staining and myelin basic protein immunohistochemistry confirmed the progressive myelin loss in the peripheral nerves. Bielschowsky silver stain revealed progressive loss of axons directly related to the severity of inflammation. Double immunohistochemistry with spectral imaging analysis revealed RhCMV-infected macrophages directly associated with the neuritis, and there was no evidence to support RhCMV infection of Schwann cells. These results suggest that peripheral nerve damage is a bystander effect secondary to inflammation rather than a direct infection of Schwann cells and warrants further investigations into the pathogenesis of RhCMV-induced peripheral neuropathy.

Pleural endometriosis in an aged rhesus macaque (Macaca mulatta): a histopathologic and immunohistochemical study.

Endometriosis is defined as the presence of endometrial tissue outside the uterine cavity and is one of the most common reproductive abnormalities encountered in women as well as Old World primates. The majority of endometriosis cases in Old World primates occur within the abdominal cavity, with spread to extraabdominal sites considered to be a rare event. A 19-year-old multiparous female rhesus macaque (Macaca mulatta) presented to necropsy for difficulty breathing and weight loss. Grossly, the animal had marked abdominal endometriosis and severe hemoabdomen and hemothorax, the latter of which was accompanied by marked pleural fibrosis. Histologic examination confirmed the abdominal endometriosis and also revealed numerous uterine glands and stroma embedded within the pleural fibrosis. Rafts of endometrial tissue were present within pulmonary lymphatics and the tracheobronchial lymph nodes. Immunohistochemically, all ectopic endometrial tissue had varying degrees of positive immunoreactivity to cytokeratin, vimentin, progesterone and estrogen receptors, and calretinin but was negative for desmin and carcinoembryonic antigen. Pleural endometriosis is an extremely rare manifestation of endometriosis in nonhuman primates. This case report emphasizes lymphatic spread as a likely mechanism for extrauterine endometriosis.

Meeting report: Spontaneous lesions and diseases in wild, captive-bred, and zoo-housed nonhuman primates and in nonhuman primate species used in drug safety studies.

The combination of loss of habitat, human population encroachment, and increased demand of select nonhuman primates for biomedical research has significantly affected populations. There remains a need for knowledge and expertise in understanding background findings as related to the age, source, strain, and disease status of nonhuman primates. In particular, for safety/biomedical studies, a broader understanding and documentation of lesions would help clarify background from drug-related findings. A workshop and a minisymposium on spontaneous lesions and diseases in nonhuman primates were sponsored by the concurrent Annual Meetings of the American College of Veterinary Pathologists and the American Society for Veterinary Clinical Pathology held December 3-4, 2011, in Nashville, Tennessee. The first session had presentations from Drs Lowenstine and Montali, pathologists with extensive experience in wild and zoo populations of nonhuman primates, which was followed by presentations of 20 unique case reports of rare or newly observed spontaneous lesions in nonhuman primates (see online files for access to digital whole-slide images corresponding to each case report at http://www.scanscope.com/ACVP%20Slide%20Seminars/2011/Primate%20Pathology/view.apml). The minisymposium was composed of 5 nonhuman-primate researchers (Drs Bradley, Cline, Sasseville, Miller, Hutto) who concentrated on background and spontaneous lesions in nonhuman primates used in drug safety studies. Cynomolgus and rhesus macaques were emphasized, with some material presented on common marmosets. Congenital, acquired, inflammatory, and neoplastic changes were highlighed with a focus on clinical, macroscopic, and histopathologic findings that could confound the interpretation of drug safety studies.