Clinical Characterization of Canine Acanthomatous Ameloblastoma (CAA) in 263 dogs and the Influence of Postsurgical Histopathological Margin on Local Recurrence

Abstract

Canine acanthomatous ameloblastoma (CAA) has been reported to be the most common odontogenic tumor in dogs. This retrospective study evaluated 263 dogs with histopathologically confirmed CAA. Within this data set, CAA presents most commonly in the rostral mandible in adult large breed dogs, with golden retriever dogs being overrepresented. Patients with appropriate follow-up after curative intent surgery were evaluated to assess the effect of histopathological margin on local tumor recurrence. No local recurrence was noted in any patient. This study raises questions about what the recommended surgical margin should be for treatment of CAA. It also serves as a stimulus for discussion as to whether further treatment for CAA is required when inadequate surgical margins are obtained, or if medical surveillance would be an appropriate management recommendation. Prospective studies are necessary to answer these questions.

Histologic margins and the residual tumour classification scheme: Is it time to use a validated scheme in human oncology to standardise margin assessment in veterinary oncology?

“…This term is rarely used in human oncology and the use of this term is not recommended according to a consensus paper by the American College of Veterinary Pathologists Oncology Committee on the evaluation and reporting of histologic margins in veterinary oncology . Furthermore, there is no consensus on what constitutes a close margin and this has not been clinically validated; 1 mm, 2 mm, 3 mm, 5 mm and 10 mm have been variably used in published veterinary studies, and 4 mm was preferred according to an online poll of veterinary pathologists . In some studies, close histologic excisions have been combined with incomplete histologic excisions, but there is no supporting literature to consider these two groups as equivalent because their outcomes have not been assessed separately .…”

Ultra‐frequent HRAS p.Q61R somatic mutation in canine acanthomatous ameloblastoma reveals pathogenic similarities with human ameloblastoma

“…Ameloblastoma is an odontogenic tumour that is rare in humans but is relatively common in dogs, particularly in golden retrievers, cocker spaniels, Akitas, Shetland sheepdogs and mixed breed dogs . As in humans, ameloblastomas in dogs are more common in the mandible than in the maxilla, and are typically locally aggressive (Figure ) .…”

“…The standard of care for ameloblastomas has traditionally been wide surgical excision of the affected area of the mandible or maxilla . However, surgery is highly invasive and may result in significant disfigurement and dysfunction . Novel therapeutic approaches based on molecular oncogenic mechanisms are expected to replace or complement current surgical solutions and thus help minimize patient morbidity while improving possible outcomes …”

“…Sample collection and experimental procedures were approved by Cornell University's Institutional Animal Care and Use Committee. All tumours were independently confirmed by histological assessment of routine haematoxylin and eosin (H&E) stained formalin‐fixed and paraffin‐embedded tumour sample by a board‐certified veterinary pathologist (GED), in accordance with previously described diagnostic criteria (Figure ). The estimated tumour content based on histological assessment was >90%.…”

“…To confirm that the HRAS p.Q61R mutation was found at high frequency specifically in CAA cases, we performed Sanger sequencing on eight independent gingival OSCC and four normal gingival samples collected from healthy dogs. Oral squamous cell carcinoma was used for comparison because this tumour type represents the most common oral malignancy of epithelial origin in dogs, and shares some histological features with CAA . All OSCC samples had wild‐type HRAS alleles, except case No.…”