Did you know that Sonopath has a branch in North Carolina? Our branch is called Carolina Veterinary Mobile Ultrasound; this case of the month highlights our Carolina Mobile sonographer Dr. Kathleen Byrnes and her ability to capture high end diagnostic views. The case was interpreted by both Dr. Eric Lindquist (DMV, DABVP, Cert IVUSS ) for the abdomen and Dr. Sara Brethel, DVM, DACVIM (Cardiology) for the cardiac images. Many thanks to Stewart’s Mountain View Animal Hospital and Dr. Lusk for their referral and trust in us! Read more to find out how a heart base mass ends up being fungal disease posing as neoplasia!
History:
The patient presented on 2/21/24 for gagging, anorexia, and low energy. The patient was found to be tachycardic at 140. However, no murmur was auscultated.
Diagnostics:
Radiographs show enlargement of cardiac silhouette.
CBC: HCT 30.1 (5.6-8.87%), WBC 24.32 (5-16.7K/uL), Neu 19 (2.9-11.6K/uL)
Chemistry: ALB 2.2 (2.3-4), ALP 1385 (23-212), Lipase 127 (200-1800)
Ultrasonographic Abdominal Findings:
- Uniformly swollen liver with hepatic lymphadenopathy and passive congestion pattern
- Pancreatic edema
Ultrasonographic Cardiac Findings:
- Concern for heart base mass affecting the pulmonary artery and associated branches, likely causing obstruction, creating the pulmonary hypertension present
- Mild mitral regurgitation which may be secondary to abnormal wall motion from increased right sided pressures. However, valvular disease cannot be definitively ruled out.
Cardiac Presentation:
The concurrent electrocardiogram shows evidence of potential right axis shift and possibly first-degree AV block.
The mitral valve leaflets are of normal thickness, and there is mild mitral regurgitation present. There is no prolapse of the mitral valve leaflets. The left atrial size is normal. Left ventricular internal dimensions during diastole suggest mild left ventricular underloading and left ventricular systolic function measures within normal limits. There is no evidence of left ventricular pseudohypertrophy. The right atrium is moderately to severely enlarged with moderate to severe tricuspid regurgitation along the free wall. Based upon tricuspid regurgitant velocities, there is moderate to severe pulmonary hypertension present. The pulmonary artery and associated branches are significantly dilated. A large intracardiac mass is present at the base that appears intertwined with the pulmonary artery branches. When color Doppler is applied, there is decreased flow over the area of the mass, but continuous flow is evident.
Discussion and Case Outcome:
Because of the fungal granuloma lodged in the bifurcation of the pulmonary artery, severe pulmonary hypertension resulted causing right heart enlargement with potential for right heart failure. Hepatic lymph node enlargement was also a concern here, and ultrasound-guided FNA of the larger node was recommended to ensure a separate comorbidity was not an issue. Due to a poor prognosis, the patient was humanely euthanized and an excisional heart biopsy submitted for histopathology.
Histopathology Findings:
- Granulomatous and suppurative inflammation characterized as severe, chronic, generalized.
- PAS stain: Intralesional fungal yeast are noted measuring approx. 13-15 microns in diameter with 1 micron wall and central basophilic body. Broad based budding is noted.
- Intralesional fungal yeast consistent with Blastomyces spp are noted.
What is Blastomyces?
Blastomycosis is a fungal disease caused by Blastomyces dermatitidis. This fungus most commonly infects humans and animals through inhalation or contamination of open wounds with spores found in the environment. Following inhalation, Blastomycosis spreads via the bloodstream throughout the body and to tissue which can include skin, subcutaneous, ocular, cardiac, bones, lymph nodes, liver, mammary chain, and vulva. Direct transmission from the nasal route into the CNS can also occur. Most affected are young, large breed male dogs mainly due to an increased chance of exposure.
In this case, a fungal granuloma was noted in the pulmonary artery. In addition to this presentation, blastomycosis has caused valvular endocarditis, myocarditis, and conduction disturbances. Diagnosis can be made by detection of Blastomyces antigen in urine. Treatment requires either amphotericin B, ketoconazole, itraconazole, or fluconazole until the patient is cleared of detectable blastomycosis for four weeks. However, up to 25% of dogs will relapse.
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