Pericardial effusion secondary to epicardial undifferentiated pleomorphic sarcoma in a young cat

Our plain-English summary of Pericardial effusion secondary to epicardial undifferentiated pleomorphic sarcoma in a young cat, by M.D. Stone, R.K. Davies, H.A. Kridel (JFMS Open Reports, 2023).

The study

• Authors: M.D. Stone, R.K. Davies, H.A. Kridel
• Journal: JFMS Open Reports
• Published: 2023;9(1):20551169231162484
• Type of article: Case report
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Case Summary: A 6.4 kg 3-year-old male neutered indoor-outdoor domestic shorthair cat was referred for further evaluation of non-resolving lethargy and hyporexia of 4 days' duration. Physical examination identified tachypnea with mild respiratory effort and muffled lung sounds bilaterally. Point-of-care ultrasound revealed a large volume of pleural and pericardial effusion (PCE), which was confirmed by thoracic radiography. Echocardiogram indicated normal cardiac function but revealed a mass-like structure along the left epicardium within the pericardial space. After 72 hours in hospital, re-evaluation via echocardiogram showed the epicardial mass lesion to have doubled in size and with apparent extension to involve the pericardium. The patient was hospitalized for 72 h of supportive care and intervention, including therapeutic pericardiocentesis, bilateral thoracocentesis, thoracic and cardiac imaging and infectious disease testing. On the third day of hospitalization, the patient developed cardiac tamponade. Further workup was discussed, including CT and subtotal pericardiectomy with biopsy, but the cat was euthanized due to clinical decline and rapid re-accumulation of effusion. Post-mortem histopathologic evaluation diagnosed an epicardial pleomorphic sarcoma, exclusive of mesothelioma or histiocytic sarcoma on immunohistochemistry (IHC).

Relevance And Novel Information: This report describes a case of epicardial undifferentiated pleomorphic sarcoma (UPS) in a young cat presenting with pleural and PCE. Pleomorphic sarcoma is a rarely reported mesenchymal neoplasia in the feline patient and has thus far primarily been identified in peripheral soft tissue structures. IHC is key to the correct histopathologic diagnosis. To our knowledge, epicardial UPS has not been previously reported in a cat.

© The Author(s) 2023.

In plain English

This case report described one cat: a 6.4 kg, 3-year-old male neutered indoor–outdoor domestic shorthair that had 4 days of lethargy and poor appetite. Fluid was found around the lungs and in the sac around the heart (pericardial effusion). Doctors drained 90 ml from around the heart and 145 ml from the chest. A heart ultrasound showed normal pumping function but a 4 cm mass in the left pericardial space. Over the next two days the mass nearly doubled in size and became attached to the heart surface and the pericardium. Large-volume fluid with cardiac tamponade, meaning fluid compressing the heart, then developed. Because the owners had concerns about treatment and prognosis, the cat was euthanized. Tissue examination after death found a pleomorphic sarcoma with mild invasion of the heart muscle. Special staining excluded mesothelioma and histiocytic tumors, so the tumor was called a pleomorphic sarcoma of unspecified origin. Tests also showed Bartonella infection, which the authors presumed was unrelated to the sarcoma. The authors concluded that this tumor on the heart surface was a novel manifestation of the disease in cats. The article does not mention asbestos.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Case report (veterinary, single cat)
• Who was studied: One 6.4 kg, 3-year-old male neutered indoor–outdoor domestic shorthair cat with lethargy and hyporexia of 4 days' duration; place and dates of care not stated
• Exposure: None. The article does not mention asbestos or any other exposure studied as a cause of the tumor. Infectious disease testing was done because the clinicians were concerned about infection of the heart.
• Main results:
  • Pericardiocentesis (draining the sac around the heart) yielded 90 ml of serosanguineous fluid, and draining the chest removed an additional 145 ml
  • Echocardiogram showed a 4 cm mass lesion in the left pericardial space
  • On a later echocardiogram the mass had nearly doubled in size, was newly adhered to the epicardium and pericardium, and large-volume pericardial effusion with new cardiac tamponade was present
  • The cat was euthanized because of the owners' concerns regarding treatment and prognosis
  • Histopathology of heart muscle and pericardial tissue showed pleomorphic neoplasia with mild myocardial invasion. Immunohistochemistry was negative for cytokeratin and ionized calcium-binding adapter molecule-1, excluding mesothelioma and histiocytic neoplasia, so the tumor was described as a pleomorphic sarcoma of unspecified origin
  • The infectious disease panel, returned after death, showed positive Bartonella henselae PCR and elevated titers: 1:128 for Bartonella vinsonii, 1:512 for Bartonella henselae and 1:1024 for Bartonella koehlerae
• The authors' conclusion: The authors concluded that the case provides a new differential for pericardial effusion in cats, and that finding this neoplasm in the epicardium is a novel manifestation of the disease in cats
• Limitations the authors state:
  • Because the owners chose euthanasia instead of surgery, the authors could not comment on treatment responsiveness or outcome
  • Blood and tissue cultures were not performed
  • The contribution of the Bartonella infection to the cat's clinical course is unknown

Topics

Medical terms in this study, explained in our Lexicon: Pericardial Effusion, Pleomorphic, Sarcoma, Ultrasound, Echocardiogram, Pericardial, Pericardium, Pericardiocentesis.

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