Primary tonsillar histiocytic sarcoma in two dogs

10 Sep 2020

Llanos, C., Lara, A., Elliott, J.

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An eight-year-old, female-spayed Golden Retriever was presented with a tonsillar mass, which was diagnosed as histiocytic sarcoma (HS), following tonsillectomy. Clinical staging revealed no regional lymph node or distant metastasis. Following adjuvant lomustine treatment, the patient remains alive with no evidence of tumour recurrence 18 months after diagnosis. Additionally, a five-year-old, male-entire Golden Retriever presented with an enlarged retropharyngeal lymph node was also diagnosed with HS. A primary tonsillar mass, extensive regional lymph node involvement and suspected early pulmonary metastasis were discovered following clinical staging. After a cytoreductive surgery and no adjuvant chemotherapy, the dog was euthanased two months following diagnosis with progressive distant metastasis. To the authors’ knowledge, this is the first report documenting primary tonsillar HS in the dog. This case report illustrates an excellent outcome of a dog with localised HS following surgery and adjuvant chemotherapy. However, prognosis remains guarded for dogs with disseminated disease, especially when chemotherapy is not used.