Case 170505-1

Nine-year-old, male castrated domestic medium hair cat

The patient had a history of lymphoplasmacytic rhinitis and pharyngitis for the past 18 months. It also had a mass in the nasopharynx, which was subsequently diagnosed as B-cell lymphoma, which was treated three times with radiation. The patient was most recently presented to the clinic due to nasal mucopurulent discharge, decreased appetite and chronic anorexia. A complete blood count revealed a moderate anemia, and a mild regenerative left shift. Chemistry analysis revealed a mild hyponatremia, hypochloridemia, low BUN, mild hyperglycemia, and a mild hypomagnesemia. The patient was placed on IV-fluid therapy due to marked dehydration, and an esophageal tube was placed for nutritional support. The patient developed subcutaneous emphysema and increased respiratory effort within 24 hrs after placement of the esophageal tube. Radiographs revealed pneumomediastinum and pneumoretroperitoneum. The patient was placed in an O2 cage but progressively deteriorated. Humane euthaniza was elected due to the poor prognosis. The patient was not vaccinated and had an upper respiratory infection as a kitten.

The animal examined is a 6.5 kg, 9-year-old, male, castrated domestic medium hair cat The superficial skin overlying the esophagostomy site is slightly red and dry. The subcutaneous tissue and superficial muscles of the head, neck and trunk are crepitant and are distended with air (emphysema).

The epiglottis, glottis and associated ligaments are bright red and diffusely wet and swollen. The left caudoventral aspect of the larynx has a 1.0-cm-long, superficial tear at the level of the posterior cricoarytenoid muscle. The tear does not seem to communicate with the tracheal lumen. The mediastinum and adjacent tissues are expanded by approximately 10 ml of red, watery fluid and pockets of air (pneumomediastinum). The lungs are diffusely red, and are collapsed against the mediastinum (presumed pneumothorax). The trachea has an 11-cm-long, 0.5-cm-wide rent is noted along the dorsal midline and the dorsal tracheal ligament is not evident in this region. Pockets of air in the muscle and adventitia surrounding this region extend to the esophagostomy site.

Other lesions are insignificant or have no bearing on the clinical presentation of this cat.

This slide has one complete and one partial transverse section through the larynx including mucosa, arytenoid and thyroid cartilage, and the beginning of the esophagus, in which there is marked, multifocal to coalescing mucosal necrosis. Approximately 80% of the laryngeal mucosa is necrotic, characterized by vacuolated, eosinophilic, fibrinous and cellular debris admixed with lymphocytes, plasma cells and neutrophils as well as smaller regions of hemorrhage and fibrin. The submucosa deep to the necrotic tissue is expanded by moderate amounts of rarefied (edematous) mucinous stroma. A small number of remnant necrotic cells have chromatin that is peripheralized by a glassy, eosinophilic inclusion body. The adjacent, inner surface of the arytenoid cartilage is mildly eroded with scalloped edges and fragmented cartilaginous debris associated with chondrocytes that have shrunken eosinophilic nuclei. Inflammation and necrosis extend beyond the arytenoid cartilage into the underlying skeletal muscle with lymphocytes, plasma cells and fewer neutrophils that dissect between myocytes causing occasional single cell myodegeneration and necrosis with irregular, wavy, distorted myofibers. Approximately fifteen percent of the esophagus has similar epithelial necrosis, inflammation and edema, principally affecting those regions adjacent to the larynx.

Immnumohistochemistry was performed for feline herpervirus-1 on sections of larynx and esophagus. Multifocal clusters of cells with intracytoplasmic and intranuclear viral antigen were detected in epithelial cells adjacent to laryngeal and esophageal ulcers.

Larynx and esophagus: Severe, acute, multifocal to coalescing, necrotizing lymphoplasmacytic, neutrophilic, and histiocytic laryngitis and esophagitis with occasional intranuclear inclusions

The laryngeal and tracheal lesions were likely caused by feline herpesvirus-1, Necrosis around the edges of the tracheal cartilage at the level where the tracheal cartilage joins with the dorsal tracheal ligament may have contributed to the destruction of the dorsal tracheal membrane, which resulted in the segmental rent noted at necropsy. The generalized emphysema pneumothorax and pneumoperitoneum were likely secondary to the rent along the dorsal tracheal membrane.

Attendees to the conference discussed the likelihood that this patient may have had a latent herpesviral infection that was reactivated by stress associated with the lymphoma and clinical.

Histopathology of the nasopharynx confirmed the presence of B-cell lymphoma, but immunohistochemical staining did not identify herpesviral antigen in areas infiltrated by the lymphoma. There was no indication of lymphoma in the slide illustrated here.

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