infection<\/a> should always be confirmed by immunohistochemical staining, ultrastructural examination, or viral isolation.
\nCytomegalovirus
\nCytomegalovirus occurs at the extremes of age, or as a result of immunosuppression, and it is a common infection in HIV\/acquired immunodeficiency syndrome (AIDS). The number of cells showing cytopathic changes can vary considerably and\u00a0parallels the severity of infection. Cytomegalovirus (CMV) primarily targets pulmonary macrophages and endothelial cells,\u00a0but virtually any cell can show cytopathic features. The most common distribution is blood-borne miliary disease but bronchiolitis and DAD also occur. The diagnostic features of infection are cytomegaly, intranuclear\u00a0inclusions with characteristic Cowdry Type B inclusions, ill-defined amphophilic intracytoplasmic inclusions that are seen with hematoxylin and eosin (H&E), PAS, and GMS stains. In patients receiving\u00a0prophylactic treatment with antivirals, CMV infection may fail to exhibit cytopathic changes. However, immunostains and\u00a0in situ hybridization will continue to identify intracellular CMV antigens.\u00a0CMV is a frequent copathogen in the immunosuppressed patient and a cause of immunosuppression in its own right.\u00a0CMV infection can be seen together with other viral infections,\u00a0Pneumocystis jirovecii, or opportunistic fungal infections<\/p>\nHerpesvirus
\nHerpesvirus types 1 and 2 both infect the lung. The incidence of herpesvirus infection increases with immunosuppression and when mucosal barrier defenses have been breached, herpesvirus characteristically elicits a prominent\u00a0neutrophilic response that mimics pyogenic bacterial infection, and foci of necrosis, cell karyorrhexis, and piled up viral\u00a0infected cells with amphophilic nuclei confirm the diagnosis. Cytopathic diagnosis includes type A or type B\u00a0Cowdry nuclear inclusions showing molding of adjacent cells with multikaryon formation. Immunosuppressed patients with herpesvirus viremia develop miliary foci of hemorrhagic necrosis with prominent fibrinous exudates.
\nHerpesvirus pulmonary infections also develop in patients with structural abnormalities of the airways or as complications of primary infections of the oropharynx and esophagus. Intubated patients receiving chronic ventilatory support and\u00a0are at increased risk due to local barotrauma from inflated endotracheal tubes. The respiratory mucosa is the primary target. At times, extensive necrosis of an ulcerated airway suggests the diagnosis but immunostaining for herpes viral\u00a0antigen can demonstrate high background staining obscuring the diagnosis. When this is the case, examining paraffinembedded tissues by electron microscopy can reveal diagnostic virions.<\/p>\n
Varicella Zoster
\nVaricella zoster pneumonia is a rare complication of the childhood chickenpox and it is more commonly encountered as\u00a0the consequence of reactivated virus in the immunocompromised host. Following nonlethal pulmonary infections in\u00a0childhood, the lung shows multiple calcified miliary lesions. Cases coming to biopsy or autopsy show miliary nodules of\u00a0hemorrhagic necrosis in lung and pleura or DAD. Infected cells with primarily Cowdry type A inclusions may\u00a0be seen at the edges of the lesion but they are harder to identify than in herpesvirus pneumonia.<\/p>\n
Hantavirus
\nThis virus produced an epidemic in the four corners region of the southwestern United States in 1993. The infection is a\u00a0zoonosis transmitted by infected rodent feces. The most common radiographic presentation is diffuse pulmonary edema\u00a0with pleural effusions mimicking congestive heart failure. Histologically, the lung shows pulmonary edema with scant\u00a0poorly formed hyaline membranes with atypical lymphocytes circulating within the pulmonary vasculature. Confirmation of the diagnosis requires specific immunohistochemistry, serological evidence of hantavirusspecific IgM and PCR or ultrastructural identification of the causative virions.<\/p>\n","protected":false},"excerpt":{"rendered":"
DNA VIRUSES Adenovirus Adenovirus primarily affects the immunosuppressed host but can produce outbreaks in healthy subjects living at close\u00a0quarters, e.g., military recruits. Adenovirus typically produces ulcerative bronchiolitis with karyorrhexis, neutrophilic […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[147],"tags":[345,343,348,346],"_links":{"self":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/565"}],"collection":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/comments?post=565"}],"version-history":[{"count":1,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/565\/revisions"}],"predecessor-version":[{"id":566,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/posts\/565\/revisions\/566"}],"wp:attachment":[{"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/media?parent=565"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/categories?post=565"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bocsci.com\/blog\/wp-json\/wp\/v2\/tags?post=565"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}