W015

Something to chew on: a rare cause of hypercalcaemia

M Abdel-Malek¹, M Phylactou¹, P C Eng¹, H Katifi¹, E Mthunzi¹, A Karra¹, D Neal²,

D Taylor², A Newland³, C Kerawala⁴, S Mehta¹

¹ Department of Diabetes, Ealing Hospital, London North West Healthcare Trust

²Ealing SDU Older People’s Services, West London Mental Health NHS Trust

³Department of Radiology, Ealing Hospital, London North West Healthcare Trust

⁴Department of Head and Neck Surgery, The Royal Marsden NHS Trust

A 71 year old gentleman with a background of ameloblastoma of the mandible, primary hypothyroidism, bipolar affective disorder and chronic kidney disease was referred from the psychiatry team with a corrected calcium of 3.09 mmol/L (normal range 2.20-2.60). He reported a three week history of constipation and loss of appetite along with unintentional weight loss over the preceding few months. He was on Levothyroxine 100micrograms daily and had previously been treated with Lithium carbonate for his bipolar affective disorder, which was stopped many years prior to admission. He was diagnosed with mandibular ameloblastoma in 2009 following a left sided mandibular biopsy but declined surgery at the time.

Further investigation of his hypercalcaemia revealed an appropriately suppressed level of Parathyroid hormone (PTH) at 0.9 pmol/L (normal range 1.6-6.9) and slightly low Vitamin D of 44nmol/L (51-163). He was biochemically euthyroid with a TSH of 2 mIU/L (normal range 0.27-4.20) and free T4 17.26 pmol/L (normal range 12-22). His 9 am Cortisol was satisfactory at 406 nmol/L and his serum angiotensin converting enzyme was also normal at 27 U/L (normal range 8-52). There was no evidence of myeloma as evidenced by normal serum immunoglobulins and urine electrophoresis. The result of his serum PTH-related peptide level is awaited.

A scan of the patient’s chest, abdomen and pelvis revealed the already known lesion on the left mandible, mediastinal lymph nodes, adenomatous adrenals and small calculi within the bladder; but no evidence of a solid malignancy.  Subsequent imaging of the neck further characterised the left mandibular lesion as partly solid and partly cystic, measuring 7.2cm by 6 by 4.6 cm, with evidence of mass effect. In addition there was a 1.5cm lytic lesion on the right mandible, associated with the root of the molar. In light of the above the case was discussed at the Head and Neck MDT at the Royal Marsden Hospital who advised intervention with a left hemimandibulectomy and simultaneous encapsulation of the right lytic lesion, which was likely to be a radicular cyst of the lower right sixth tooth.

Ameloblastoma is a very rare, benign tumour that develops most often in the jaw near the molars.  It can be very aggressive, growing into the jawbone and causing swelling and pain. Malignant transformation is rare as are metastases, but they do occur, and both may be associated with hypercalcaemia. Here we present a case of hypercalcaemia in a gentleman with known ameloblastoma of the mandible, in whom all the common causes of hypercalcaemia have been excluded, raising the possibility that the new hypercalcaemia signifies malignant transformation of his previously benign ameloblastoma.