Progressive respiratory distress caused by a laryngeal histiocytic sarcoma in a European rabbit (Oryctolagus cuniculus)

Abstract

Histiocytic sarcoma (HS) represents a rare type of malignant disease, characterized by neoplastic proliferation of interstitial dendritic cells (iDCs). In rabbits, there are only two previous reports of HS with pulmonary and cutaneous primary localizations. A 2-year-old, male, European rabbit (Oryctolagus cuniculus) with a clinical history of chronic respiratory distress and progressive weight loss was necropsied. Postmortem examination revealed a gray-white, well-demarcated ovoid mass that deformed the ventral region of the larynx. Similar nodules were identified in both lungs. Histologically, the laryngeal mass and pulmonary nodules were composed of dense sheets of neoplastic histiocytes with marked atypia and multinucleated neoplastic cells. Immunohistochemically, the neoplastic cells were intensely positive for Iba1, CD1a, and vimentin, occasionally for E-cadherin, and negative for multi-cytokeratin. A diagnosis of laryngeal HS with multiple pulmonary metastases was made. To the authors' knowledge, laryngeal histiocytic tumor has not been previously reported in rabbits.