Sir, we write to inform you of a recent case of interest. A 54-year-old gentleman was referred to the oral and maxillofacial surgery clinic by his general dentist with a lower second molar tooth becoming mobile and intraoral radiographs revealing resorption of the roots. The tooth had been becoming increasingly loose over a six-week period with no associated discharge, swelling or paraesthesia in the region. The patient reported no unexplained weight loss, loss of appetite, voice changes, increasing malaise or family history of cancer or haematological malignancy.

He was normally fit and well, taking no regular medications, drinking five units of alcohol per week and had never smoked.

On examination, the patient had no cervical lymphadenopathy, axillary lymphadenopathy or hepatosplenomegaly and cardio-respiratory examination was also unremarkable (Fig. 1).

Figure 1: Orthopantomogram radiograph showing the left mandibular second molar and associated well-defined periradicular radiolucency extending to the superior border of the inferior dental canal.
figure 1

Note: bilateral tonsilloliths giving the appearance of multifocal radiopaque punctate areas

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The mobile tooth was removed and curettage content of the extraction socket was sent for histopathology, given the atypical presentation of what was thought to be a dental-related pathology. A possible differential diagnosis was primary intraosseous carcinoma. The initial pathology report showed features of a dense lymphoid infiltrate highly suspicious of B-cell lymphoma. Wider excision by means of an alveolectomy provided adequate tissue that confirmed diffuse large B-cell lymphoma (stage 1E).

The patient experienced no 'B symptoms' such as night sweats, fever, persistent skin itching, persistent cough or breathlessness. Blood tests taken as part of the diagnostic work-up were normal and the PET CT scan showed the disease was confined to the left mandible only (Fig. 2).

Figure 2
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Coronal view from the CT scan showing tumour invasion of the cancellous bone in the left body of mandible

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The patient received chemotherapy with rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone, known as R-CHOP. Lymphomas represent 3.5% of all intra-oral malignancies in the head and neck, lymphoma being the second most common neoplasm after squamous cell carcinoma. We note stage 1 median survival time for stage 1E non-Hogkin's lymphoma (NHL) is ten years.1 After six cycles of R-CHOP chemotherapy with adjuvant involved field radiotherapy completed, the patient is in remission and was last reviewed on clinic in March 2017.

More than 12,000 people are diagnosed with non-Hodgkin's lymphoma in the UK every year, with the average age of diagnosis being 50–55 years.2 NHL usually presents with a painless swelling in a lymph node in the neck, armpit or groin,2 although 24% of cases affect extra-nodal locations.3 Diffuse large B-Cell lymphoma is the most common subtype of non-Hodgkin's lymphoma in the head and neck. The commonest site of NHL in the oro-facial region is Waldeyer's lymphatic ring.4

There are few other case reports documenting the mandibular presentation of B-Cell lymphoma. A. Bugshan et al. (2015)1 described a patient presenting with swelling of the cheek and unilateral numbness of the lower lip. R. Kini et al.3 (2009) talk of a firm, insidious swelling of the right mandible without any loss of sensation.

The learning point from this case is the unusual presentation of the disease and without the appropriate index of suspicion in a case which could have been easily dismissed as periodontal disease, there was a real risk of misdiagnosis and adverse sequelae. It is a rare, uncommon case with only 0.6% of isolated malignant non-Hodgkin's affecting the mandible5,6 but we feel that this rare presentation should be considered as a reminder that haematological malignancies such as lymphoma can present in the extranodal areas of the head and neck. The most common presenting symptoms in the head and neck region are painless swellings (most commonly in the maxilla), unexplained tooth mobility or bone pain and discomfort. Radiographs may reveal tooth root resorption and a unilocular radiolucency mimicking dental pathology.