Bicavitary eosinophilic effusion in a dog with coccidioidomycosis

Eosinophilic pericardial effusion and pericarditis in a cat

Case summary

A 10-year-old domestic shorthair cat presented for lethargy, anorexia and labored breathing. Significant pleural and pericardial effusions prompted thoracocentesis and pericardiocentesis. Cytologic evaluation of the pericardial effusion revealed a highly cellular hemorrhagic, eosinophilic (12%) effusion, with many markedly atypical suspected mesothelial cells, interpreted as concerning for neoplasia. Thoracoscopic subtotal pericardiectomy and histology of the pericardium revealed predominantly eosinophilic inflammation with multifocal mesothelial hypertrophy and ulceration. A peripheral eosinophilia was not present on serial complete blood counts. Initial infectious disease testing was mostly negative. Toxoplasma gondii titers were most consistent with prior exposure, although reactivation could not be excluded. The owner's medical history included a prior diagnosis of bartonellosis. Owing to the challenges of definitive Bartonella species exclusion, the cat was treated empirically with pradofloxacin and doxycycline, and a subtotal pericardectomy. There was improvement at first but pleural effusion recurred approximately 3 months after discharge. The cat was euthanized and a necropsy was not performed. Subsequent pericardial effusion Piroplasma/Bartonella/Borrelia droplet digital PCR detected DNA of Bartonella vinsonii subspecies berkhoffii, and peripheral blood culture and sequencing revealed a rare apicomplexan organism (90% homology with Colpodella species) of unknown clinical significance. Testing for filamentous bacteria and fungal pathogens was not performed.

Relevance and novel information

This case offers several unique entities - eosinophilic pericardial effusion and eosinophilic pericarditis of unknown etiology - and illustrates the well-known marked atypia that may occur in reactive and hyperplastic mesothelial cells, particularly of infrequently sampled and cytologically described feline pericardial effusion, supporting a cautious interpretation of this cytology finding.

Bicavitary eosinophilic effusion in a dog with coccidioidomycosis

This is a case of coccidioidomycosis in a dog, examined for vomiting and labored breathing. Physical examination and thoracic and abdominal imaging revealed pleural and peritoneal effusions, both of which exhibited neutrophilic inflammation with a substantial eosinophilic component. The dog had positive IgM and IgG coccidioidomycosis titers at initial evaluation. The eosinophilic component of the inflammation was attributed to coccidioidomycosis. The dog underwent approximately 6 months of fluconazole treatment, with both effusions and clinical signs improving after 6 weeks. Three months after cessation of antifungal treatment, the dog developed a mid‐diaphyseal lytic and proliferative lesion in the left radius caused by Coccidioides spp. This case illustrates the importance of consideration of coccidioidomycosis when an eosinophilic cavitary effusion is present in dogs that live in or have traveled to endemic regions.