Presentation
Presented with respiratory distress and a right axillary mass.
Patient Data
There is a severe narrowing of the thoracic trachea and carina. The cranial and caudal mainstem bronchi on the right side are markedly narrowed on the DV projection. The pulmonary vasculature is within normal limits. The cardiac silhouette is normal. There is increased opacity dorsal to the heart on the right lateral projection which is not confirmed on the other projections. On the DV view there is an increased soft tissue opacity associated with gas opacity in the caudal mediastinum. Pleural fissure lines are identified on the DV view. In the viewable abdomen the liver is mildly enlarged.
Tracheal and bronchial collapse, may be degenerative, due to severe inflammation, or hemorrhage. The soft tissue opacity visible in the caudal thorax is suggestive of transient hiatal hernia, however alveolar pattern in the accessory lung lobe is possible.
Case Discussion
Airway collapse was confirmed on bronchoscopy and no organisms were cultured on bronchoalveolar lavage.
Biopsy of the axillary mass found intralesional oval yeast and hyphal form fungal organisms with budding and nondichotomous branching, diagnosed as hyalohyphomycosis. The disseminated fungal infection was present in the right axilla, thoracic lymph nodes, liver and spleen. Talaromyces helicus was cultured from the lymph node. This was likely an opportunistic infection.
The conformation of the dog, with a typical widened mediastinum and increased body condition, masked the sternal and tracheobronchial lymphadenopathy seen on necropsy. Radiographs are not sensitive for lymph node enlargement in the mediastinum, and a CT could have provided more information if the patient were stable. The tracheal collapse was a complicating factor in the dog's presentation and led to mechanical ventilation before euthanasia. While each problem (airway collapse, fungal infection, and anemia) were treatable, together they indicated a poor prognosis and euthanasia was elected.
Multifocal lymph node and enlargement is consistent with a disseminated disease, which was suspected to be infectious based on the lymph node cytology of granulomatous inflammation. The lungs were not directly involved on necropsy examination, however the respiratory tract is a common site of entry for fungal infections.
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