Rostral mandibulectomy to manage an oral papillary squamous cell carcinoma in a labrador

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rostral mandibulectomy
In this post-operative photo following the rostral mandibulectomy, the shorter appearance of Fluffy’s jaw is to be expected.

Subedited by Dr Phil Tucak

Fluffy is a 10-year-old female spayed labrador who was referred to the dentistry service at Queensland Veterinary Specialist (QVS) North Lakes in October 2020. Fluffy presented with a recurrent oral mass that was previously excised and biopsied by the primary veterinarian in May 2020. 

The oral mass was associated with the missing mandibular first incisors—which had been extracted by the primary veterinarian on the biopsy day, and the histopathology revealed a ‘fibrous epulis’ that represented a benign hyperplasia rather than a neoplastic process. At the time, no further treatment was performed by the primary veterinarian based on the reported histopathology result. 

During the oral exam of Fluffy at QVS, the recurred oral mass appeared to be mildly ulcerated and inflamed with proliferative tissues on the surface. The mass was associated with the buccal aspect of the left mandibular third incisor extending to the buccal and mesial aspect of the right mandibular second incisor. 

Another biopsy and histopathology were recommended as the recurred oral mass did not appear or behave as a benign fibrous hyperplasia.

On the day of the biopsy, Fluffy was anaesthetised, right and left inferior alveolar nerve blocks were performed with 0.5% bupivacaine at 1mg/kg (dose was divided by four quadrants) along with regional dental radiograph of the mandibular incisor region. 

rostral mandibulectomy

The dental radiographs revealed no to minimal changes on the surrounding alveolar bone. The oral mass was measured approximately 20mm in length, 15mm in height, and 9mm in width (Fig 1). 

It had a pedunculated attachment to the underlying gingiva at its base. An incisional biopsy was performed using a scalpel blade no.15 without compromising the adjacent structure and the cut was done at the base of the mass. A simple interrupted suture was placed on the incisional biopsy site using a 4-0 Monocryl suture material. 

The sample was placed in a 10% formalin jar and sent to a pathology lab for further histopathology diagnosis. The patient received an injection of non-steroidal anti-inflammatory after the procedure and was prescribed with two-day course of non-steroidal anti-inflammatory.

The second histopathology results revealed an oral papillary squamous cell carcinoma. The results and treatment options were discussed with Fluffy’s owner. Oral papillary squamous cell carcinoma in dogs is a rare and locally invasive neoplasm. Its oncogenesis is poorly understood and there have been numerous debates as to whether it is a histologic variant of squamous cell carcinoma, analogous verrucous carcinoma, a distinct entity, or related to papillomavirus. 

Unlike the squamous cell carcinoma, the papillary squamous cell carcinoma is reported to be rarely metastasised. Due to the locally aggressive nature of this neoplasia, a CT scan of the skull was recommended to evaluate the regional lymph nodes and any potential bony invasion on the region that the previous dental radiographs could not detect.  

In addition, a rostral mandibulectomy with a minimum of 1cm margin was recommended to prevent recurrence.

The CT scan and rostral mandibulectomy were performed three weeks following the discussion with the owner. The CT scan did not reveal any enlargement of the regional lymph nodes (mandibular and retropharyngeal) and there was a mild alveolar bone lysis on the area of missing right and left mandibular first incisors which was suspected due to the previous extraction site and not associated with the concurrent oral papillary squamous cell carcinoma. 

The biopsy site has healed without suture material, inflammation, or ulceration. The right and left inferior nerve block were performed using 0.5% bupivacaine. 

Fluffy was positioned in dorsal recumbency, the ventral rostral mandible was clipped and aseptically prepared for the rostral mandibulectomy. A 1cm clean surgical margin was aimed for the rostral mandibulectomy and a surgical marker pen was used to mark the 1cm margin peripherally surrounding the original lesion. 

The 1cm margin incorporated the right and left mandibular canines to the excision. The mandibulectomy was performed using a combination of dental burs (Lindemann, 701L, and round cutting burs), a surgical chisel, and a mallet. 

The retained roots of right and left mandibular canines were also surgically extracted prior to the reconstruction of the lower lip following the mandibulectomy (Fig 2-4). The lower lip was reconstructed and surgically closed without any tension to minimise the risk of wound dehiscence during recovery (Fig 5-7). 

A Fentanyl transdermal 50mcg was placed postoperatively and the patient also received a subcutaneous injection of non-steroidal anti-inflammatory. The patient was hospitalised overnight for close monitoring and pain management with Fentanyl CRI for at least 12 hours while waiting for the Fentanyl transdermal to be active. Fluffy was discharged to her owner the next day with a five-day course of broad-spectrum antibiotic and non-steroidal anti-inflammatory. 

It is unknown whether the initial diagnosis of ‘fibrous epulis’ was a true representation of the lesion that potentially had transformed to a different entity five months after the initial biopsy or whether it was originally a papillary squamous cell carcinoma not detected on the first histopathological analysis. 

This case study highlights the importance of good communication between the clinician and pathologist upon submitting and analysis of a biopsy sample. A good lesion description, history, and providing clinical photographs are also always recommended.

Moreover, further discussion with the veterinary pathologist is advised if the initial histopathology result does not fit the clinical picture.


rostral mandibulectomy

Dr Williana Basuki BVSc (Hons) MS MANZCVS DAVDC

Board Certified in Veterinary Dentistry (Registered Specialist)

Queensland Veterinary Specialists

Dr Basuki was born and grew up in Jakarta, Indonesia. She earned her veterinary degree at the University of Queensland in 2010. 

Following veterinary school, Dr Basuki worked as a small animal veterinarian before entering a year of rotating internship followed by a year of surgery internship at Queensland Veterinary Specialists (QVS). 

She pursued her dream to become a specialist in veterinary dentistry and undertook a three-year residency in Dentistry and Oral Surgery along with a master’s degree at Colorado State University, USA. Following her residency, Dr Basuki became a Diplomate of the American Veterinary Dental College by examination and worked as a full-time veterinary dentist at Tufts Veterinary Emergency & Specialties in Massachusetts (USA). 

During her time at Tufts University, Dr Basuki was also heavily involved in teaching veterinary dentistry to veterinary students and held an Adjunct Associate Professor position. She also delivered numerous lectures and was involved in multiple continuing education programs at different conferences.

Dr Basuki returned to Australia in 2020 and joined QVS as the first and only registered specialist in veterinary dentistry (small animal) in Queensland. 

There she offers her expertise in routine and advanced dental and oral surgery cases such as periodontal therapy, full mouth extractions, root canal therapy, crown height reduction, vital pulpotomy, oral biopsy and diagnostic imaging, mandibulectomy, and other dental procedures. 

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