A delayed and difficult diagnosis of oral squamous cell carcinoma: a case report

Case report

A 47-year-old fit and well male patient, who was also a non-smoker, was initially referred on a two-week wait referral pathway after his GDP noted an unusual pattern of severe recession of the gingivae around his lower left third molar, which was grade II mobile. This was diagnosed as a periodontally involved mandibular third molar, despite there being no evidence of periodontitis in the patient's remaining dentition. The patient was removed from the two-week wait pathway, and a routine appointment was made for the extraction of the tooth, with no follow up.

Following a failure to heal of the extraction socket, the patient presented to a number of dentists working in both primary and secondary care. He was treated for a suspected retained root, dry socket and infected socket. No further investigations were undertaken at this point. Three months after the extraction of the mandibular third molar, with still no improvement of the patient's condition, the patient was referred to the oral and maxillofacial unit. The patient complained of a of severe, debilitating pain from the area. Clinically, the socket had still not healed, and there was a tender, firm swelling on the lingual aspect of his mandible.

Initial investigations

Initially, an OPG was taken that showed no abnormalities in the area of the lower left third molar, which was extracted (Figure 1). Superficial biopsies were taken from the socket and reported as hyperplastic squamous epithelium and chronically inflamed fibromuscular tissue, no neoplasia was identified. Superficial biopsies were initially taken owing to the close proximity of the affected area with the lingual nerve. Despite administering local anaesthetic, the patient was still experiencing severe pain. At this point, an MRI was taken, which showed a significant area of inflammation affecting the left lingual alveolar and floor of mouth, but with no evidence of anything sinister. The initial diagnosis was that of an inflammatory mass on the left side of mandible, and the patient was started on long-term co-amoxiclav.

Further investigations

At a review appointment 6 weeks later, the patient's condition had still not improved. On examination, the socket had now healed, but the lingual swelling was still present. The patient then underwent a CT mandible that raised suspicions owing to an area of erosion on the inner cortex of the mandibular ramus (Figure 2). This led to the area being formally explored under general anaesthetic. A lingual flap was raised that revealed dense, thickened periosteum and a significant bony defect on the lingual aspect of the mandible extending posteriorly from the tooth socket. Granulation tissue from the tooth socket, tissue from the bony defect lingually and the mucosa overlying the extraction socket were all sent for histopathology. Histopathological analysis confirmed an invasive well to moderately differentiated squamous cell carcinoma (Figure 3). A further MRI of the neck was carried out that showed progression since the previous CT. A final diagnosis of pT4aN0M0, moderately differentiated, non-cohesive squamous cell carcinoma of the left mandibular alveolus was established. The tumour reached an overall size of 32 x 22 x 21 mm and invaded submucosa, bone, floor of mouth lymph node and submandibular gland causing a bony defect measuring 22 x 21 mm.

Management

The patient underwent a left mandibular resection, left neck dissection and deep circumflex iliac artery (DCIA) reconstruction (Figure 4) followed by a 6-week course of post-operative radiotherapy. The primary resection histopathology report indicated clear margins, albeit close in the posterior aspect along with perineural invasion but no vascular invasion. The neck was also clear of any metastases. Radiotherapy was offered on the basis of perineural and bony invasion as per our current standards for post-operative treatment to reduce the risk of local regional relapse. On a further review, there was no sign of recurrence and the patient was making a good recovery.

Discussion

SCCs affecting the alveolar ridge, such in this case, are thought to account for 9% of oral SCC cases, and due to their rarity, there is limited published work on SCCs affecting the alveolar ridge and their varied presentations.⁸ SCCs of the alveolar ridge commonly occur in the molar and premolar regions. In the case of dentate patients, this type of cancer may invade the periodontal ligament space of teeth, which can cause mobility or gingival bleeding, both of which may be misdiagnosed as periodontal disease. This cancer may also present as proliferative tissue at the gingival margins or as superficial gingival ulceration. In edentulous patients, the patient may complain of a sudden difficulty in wearing dentures they have had for many years. Malignant tumours, such as in this case, that arise from the oral mucosa may also prevent a socket from healing following exodontia. This is thought to be due to tissue necrosis occurring, which may act similarly to a foreign body in a socket, or these tumours can also cause ischaemia that can prevent healing.⁹

Dentists are fundamental in identifying oral SCCs early and this case highlights the importance of being able to recognize varied and less common presentations of SCCs. For all patients, it is imperative to obtain a full history, conduct a detailed physical and full radiographical examination to aid diagnosis. A mobile isolated tooth or localized gingival or mucosal lesions in an otherwise healthy mouth should be regarded as something more sinister.³ A full history will also allow other risk factors for SCC to be identified, such as tobacco smoking or alcohol consumption, which may make the practitioner more suspicious of a malignant rather than odontogenic cause. Although useful, practitioners should not rely on the presence of risk factors to guide a differential diagnosis of a malignant cause because oral SCCs may present in patients who are non-smokers and who have limited alcohol intake, such as in this case.

As well as mobility of teeth, a delay or failure to heal of an extraction socket is also an extremely common presentation in both primary and secondary care. When presented with a non-healing socket, a number of considerations should be taken into account. Common diagnoses should be ruled out first, such as alveolar osteitis or infection due to foreign bodies. A number of systemic patient factors should also be considered when there is a delay in healing, such as the patient's age, past medical history and metabolic status.¹ Suspicion should be raised when these have been ruled out and there is still no response to initial therapies.¹⁰ This warrants the need for further investigations and possible referral onto secondary care. For any cases where there is a doubt about the diagnosis, regular review in either primary or secondary care should be undertaken to ensure a diagnosis is established and to maintain the patient's confidence in the profession.

The initial investigations were a diagnostically challenging aspect of this case. The initial MRI showed only a significant area of inflammation affecting the lingual alveolus and floor of mouth, but no evidence of anything sinister. There was also some difficulty in obtaining the initial biopsy from the extraction site due to the severity of pain the patient was experiencing despite the area being anaesthetized. Histopathological analysis of samples from a non-healing socket should still be obtained to aid diagnosis, alongside radiographic investigations. In this case, the CT mandible was undertaken because there had been no improvement of the patient's condition. This led to formal exploration of the area under GA and a definitive diagnosis being established. Despite MRI and CT being comparable in the literature in terms of sensitivity and specificity for cancer detection, an MRI has been reported to be better for the detection of tumours, demonstrating perineural spread and identifying any bony invasion of the mandible.¹¹ Further imaging should therefore be considered if there is still no definitive diagnosis after initial imaging, and no improvement on the patient's condition.

Conclusion

We have presented a diagnostically challenging case of a well to moderately differentiated squamous cell carcinoma of the lingual alveolus that initially presented as an isolated mobile mandibular third molar and a subsequent non-healing socket. We encourage practitioners to conduct a thorough history, clinical and radiographic examination even when the diagnosis may appear obvious. Malignant causes should be considered, even if the patient is considered ‘low risk’ for oral SCC. This case demonstrates the delays in diagnosis that can occur, and the need for these patients to be seen in a timely manner for further investigations. Timely referral ensures prompt treatment, which can lead to increased survival probability and quality of life for the patient following treatment. Further to this, it demonstrates the importance of imaging techniques and histopathological analysis when the diagnosis remains uncertain and there is a failure to respond to initial treatment.