Pleural malignant lymphocytic effusion in a feline: case report

Abstract

Pleural effusion, defined as the abnormal accumulation of fluid in the thoracic cavity, is a common condition in feline clinical practice. In most cases, it represents an emergency due to respiratory compromise, characterized by clinical signs such as orthopneic posture, dyspnea, and cyanotic mucous membranes. Various conditions can lead to this alteration, such as feline infectious peritonitis, mediastinal neoplasia, and congestive heart failure. Therefore, laboratory analysis of the drained fluid provides crucial information for diagnostic purposes. The laboratory analysis of pleural effusion includes physical, chemical, and cytological evaluations, categorizing it as pure transudate, modified transudate, or exudate. The fluid can also be classified as septic exudate, chylous effusion, hemorrhagic, bilious, or neoplastic. This study describes the cytological findings of a pleural effusion with marked cellularity, composed of lymphocytes exhibiting various malignant criteria, identified as malignant lymphocytic effusion. The effusion was collected via thoracentesis from an eight-year-old domestic mixed-breed cat.