Clinicopathologic, immunohistochemical, and ultrastructural features of histiocytic sarcoma in a chinchilla (Chinchilla lanigera)

Abstract

A 9-year-old intact female chinchilla (Chinchilla lanigera) was presented to a referring veterinarian due to small, multiple cervical nodules that had been rapidly increasing in size and number. Cytology of the nodules revealed sheets of pleomorphic round cells that were morphologically most compatible with histiocytic sarcoma. Histologically, the nodules were fairly demarcated, partially infiltrative, densely cellular neoplasm, and was composed of pleomorphic large round cells arranged in sheets. Special stains for bacteria (Gram stain and Ziehl-Neelsen stain) and fungi (periodic acid-Schiff stain) were all negative. On immunohistochemistry, the neoplastic cells showed strong cytoplasmic positivity for Iba-1 and CD204, but were negative for CD3 and CD20. Transmission electron microscopy failed to detect Birbeck's granules in the cytoplasm of the neoplastic histiocytes. The chinchilla received chemotherapy with lomustine but died spontaneously on day 62 despite treatment. Autopsy with histopathologic examination revealed disseminated histiocytic sarcoma involving the bone marrow, bronchial lymph nodes, nasal cavity, lung, heart, stomach, pancreas, pancreatic lymph nodes, liver, spleen, and kidney. To the best of our knowledge, this is the first report of disseminated histiocytic sarcoma in chinchillas.

Disseminated histiocytic sarcoma in a degu (<i>Octodon degus</i>)

“…Histiocytic sarcoma has been reported in various mammalian, avian, and reptilian species [ 1 , 2 , 3 , 4 , 7 , 8 , 9 , 10 , 12 , 13 ]. The histological appearances of histiocytic sarcomas are variable and generally classified into two phenotypic subtypes: spindle cell type and round-polygonal cell type [ 1 , 8 ].…”

“…The histological appearances of histiocytic sarcomas are variable and generally classified into two phenotypic subtypes: spindle cell type and round-polygonal cell type [ 1 , 8 ]. In hystricomorph rodents, histiocytic sarcoma has been reported in a chinchilla, but not in guinea pigs [ 2 ]. The disseminated histiocytic sarcoma of the chinchilla involved multiple organs, and the histological findings were similar to those of the present case [ 2 ].…”

“…In hystricomorph rodents, histiocytic sarcoma has been reported in a chinchilla, but not in guinea pigs [ 2 ]. The disseminated histiocytic sarcoma of the chinchilla involved multiple organs, and the histological findings were similar to those of the present case [ 2 ]. In histiocytic sarcoma of mice, intracytoplasmic eosinophilic hyaline granules of the proximal renal tubules, which were positive for lysozyme, were observed in 42 out of 58 mice [ 4 ].…”

“…To differentiate histiocytic sarcoma from these tumors, immunohistochemical staining using histiocytic markers such as Iba-1, CD204, HLA-DR, and CD163 is helpful [ 9 , 10 ]. Similarly in exotic pet medicine, the immunohistochemical markers have been used to diagnose histiocytic sarcomas in four-toed hedgehogs, a chinchilla, a central bearded dragon [ 2 , 3 , 8 ]. Poorly differentiated sarcoma and anaplastic sarcoma with giant cells in degus were immunonegative for Iba-1 [ 12 ].…”