Malignant collision tumors in two dogs

Abstract

CASE DESCRIPTION A 13-year-old Labrador Retriever with a 4-cm-diameter ulcerated perianal mass and a 12-year-old Golden Retriever with a 5-cm-diameter ulcerated caudolateral abdominal mass were brought to a referral oncology practice for evaluation of the dermal masses. Both masses were resected with wide margins without reported postoperative complications. For both dogs, a diagnosis of collision tumor was made. The database of the Veterinary Diagnostic Laboratories at Colorado State University was searched for other examples of collision tumors in dogs. CLINICAL FINDINGS Histologic assessment of the masses revealed collision tumors in both patients. The perianal mass was diagnosed as a perianal gland carcinoma with adjacent hemangiosarcoma. The flank mass was diagnosed as a fibrosarcoma with an adjacent mast cell tumor. The university database search of sample submissions in 2008 through 2014 for the keywords collision, admixed, or adjacent yielded 37 additional cases of dogs with malignant nontesticular collision tumors. TREATMENT AND OUTCOME Both dogs were treated with surgery alone and received no adjunctive treatments. Both tumors were completely excised. There was no evidence of either local tumor recurrence or metastasis in the Labrador Retriever and the Golden Retriever at 1,009 and 433 days after surgery, respectively. CLINICAL RELEVANCE Collision tumors are rare, and there is minimal information regarding treatment recommendations and outcome for animals with collision tumors. On the basis of the 2 cases described in this report, the outcome associated with treatment of collision tumors may be similar to the expected outcome for treatment of any of the individual tumor types in dogs.

Clinicopathological Diversity of Canine Mammary Gland Tumors in Sri Lanka: A One-Year Survey on Cases Presented to Two Veterinary Practices

“…Therefore, apart from being classified as a mammary carcinoma, it was identified as a collision tumor referring to the mixed presentation. Collision tumors are a type of a mixed tumor with 2 foci of neoplasia which develop adjacent to one another, yet remain separate [ 28 ]. These tumors are rare, and there is minimal information regarding treatment recommendations and outcome for animals [ 28 ].…”

Mast Cell Tumour and Mammary Gland Carcinoma Collision Tumour. Case report and literature review.

“…Various etiopathogenetic hypotheses explain the developing mechanisms of CTs. Random development in the same venue of two different primary tumours; simultaneous development under the influence of the same carcinogenic factor (i.e., radiation) of two morphologically distinct neoplasms; alteration or interaction of the microenvironment induced by the presence of a primary tumour which produces epidermal or stromal changes that allow the development of a second independent neoplasm through paracrine effects (Bulte et al, 2020;Mancebo et al, 2015;Scott et al, 2017).…”

“…CTs, at the clinical and macroscopical examination, resemble a single tumour. Histological and immunohistochemical analysis reveals two phenotypically distinct cell populations that maintain sharp, distinct boundaries and can be composed of two benign tumours, a benign and a malignant tumour, or two malignant tumours (Bulte et al, 2020;Mancebo et al, 2015;Pallatto & Bechtold, 2018;Rodríguez et al, 2016;Scott et al, 2017).…”

“…In veterinary medicine, the literature on CTs is limited to very few case reports. In dogs have been described collisions of gingival squamous cell carcinoma and melanoma (Rodríguez et al, 2016); cutaneous melanoma and anaplastic sarcoma in the upper lip (Jakab & Balka, 2012); canine hepatoid gland carcinoma and perianal hemangiosarcoma (Andras et al, 2010,); a case of mast cell tumour and fibrosarcoma in the skin (Scott et al, 2017); mast cell and plasma cell collision tumour in the spleen (Pallatto & Bechtold, 2018) and a case of collision tumour of two nodal metastases of apocrine gland adenocarcinoma and vulvar mast cell tumour (Gibson et al, 2020). Veterinary literature reports are resumed in Table 1.…”

Collision tumour of two nodal metastases (adenocarcinoma and mast cell tumour) in a dog

“…According to most sources examined, collision tumours occur when two independently coexisting, histologically and genetically distinct tumours are closely associated but microscopically separate within a single macroscopic mass. [1][2][3] A collision tumour should be differentiated from a composite or mixed tumour that is defined as a tumour arising from one cell type or clone (eg, partly differentiated stem cell) that differentiates into two or more phenotypically diverse cell lines 1 4 (eg, a mixed canine mammary carcinoma). Microscopically, a mixed or composite tumour will have admixing of the cell types, whereas in a collision tumour, both cell types are present but separate.…”