Tumour lysis syndrome and oncologic emergencies: SAQ

This boy with the Burkitt lymphoma sits at the very top of the tumour lysis risk, and the first decision is to put the prophylaxis in place before the first dose of the chemotherapy, and to prepare the supportive care for the clinical syndrome if it declares. The framework that organises the answer is the risk stratification, the Cairo-Bishop definition, and the airway-first and the steroid-first principles for the structural emergencies. [3]

Question 1 (10 marks)

Outline your assessment of this boy's tumour lysis risk and the prophylaxis you would put in place before the first dose of chemotherapy, and then discuss how you would recognise and manage the tumour lysis syndrome if it declares. [1]

A full-mark answer reproduces the risk assessment, the prophylaxis by the risk group, the Cairo-Bishop definition, and the stepwise management of the declared syndrome. [3]

Risk assessment (2 marks). The Burkitt lymphoma carries the very highest tumour lysis risk, because of its rapid doubling time of around twenty-four hours and its large mass. The high lactate dehydrogenase and the large abdominal mass confirm the high tumour burden, and the host features of the pre-existing renal function, the hydration, and the urine output refine the risk further. This boy is high risk by the Cairo stratification. [3]

Prophylaxis before the first dose (4 marks). The foundation is the hyperhydration with an isotonic fluid that contains no potassium, run at two to three litres per square metre per day to maintain a urine output above two millilitres per kilogram per hour. The fluid is potassium-free because the child is at risk of the hyperkalaemia. The rasburicase, a recombinant urate oxidase that converts the existing uric acid into the soluble allantoin, is given at zero point one five to zero point two milligrams per kilogram as a single dose or daily for up to five days, and the glucose-six-phosphate-dehydrogenase status is checked first because the rasburicase is contraindicated in the deficiency. The biochemistry is monitored every four to six hours for the first twenty-four to forty-eight hours. [1][4]

Recognition by the Cairo-Bishop definition (2 marks). The laboratory tumour lysis syndrome is two or more of the urate over four hundred and seventy-six micromoles per litre, the potassium over six millimoles per litre, the phosphate over two point one millimoles per litre in the child, and the corrected calcium under one point seven five millimoles per litre, within three days before to seven days after the cytotoxic therapy. The clinical form adds the acute kidney injury, the cardiac arrhythmia or sudden death, or the seizure. [2]

Management if it declares (2 marks). The hyperkalaemia is the immediate killer, and the calcium gluconate is given the moment the ECG shows the severe changes, followed by the insulin with the glucose and the salbutamol to shift the potassium into the cell. The asymptomatic hypocalcaemia is not corrected in the high-phosphate state, because the correction drives the calcium-phosphate deposition and worsens the kidney injury. The refractory hyperkalaemia, the oliguria, and the volume overload are the indications for the renal replacement therapy. [5]

Question 2 (10 marks)

Discuss how your management of his airway and his neurological status would differ if his presentation instead included a large anterior mediastinal mass with the facial swelling, or a progressive leg weakness with the bowel and bladder change. [5]

A full-mark answer reproduces the airway-first no-sedation principle for the mediastinal mass and the urgent imaging and steroid principle for the cord compression. [7]

The anterior mediastinal mass and the superior vena cava syndrome (5 marks). A large anterior mediastinal mass with the facial swelling and the raised jugular venous pressure is an anaesthetic catastrophe waiting to happen, because the loss of the muscular tone under the sedation or the anaesthesia can collapse the trachea against the tumour within seconds. The child is kept upright, the supplemental oxygen is given, and the sedation is avoided until the airway is secured in a controlled setting. The tissue diagnosis is made by the least-invasive route, the peripheral flow cytometry, the effusion cytology, the bone marrow, or the superficial node biopsy under the local anaesthetic. The steroids or the emergency radiotherapy are given first if the airway obstruction is critical, accepting that they may obscure the diagnosis, because the airway is the priority. [5]

The spinal cord compression (4 marks). The back pain with the leg weakness and the bowel or bladder dysfunction is a malignant cord compression until the magnetic resonance imaging proves otherwise, and the ambulation at the presentation is the strongest predictor of the ambulation at the outcome. The intravenous dexamethasone is started early to reduce the cord oedema, the urgent whole-spine magnetic resonance imaging defines the level and the cause, and the definitive management is the emergency decompression, the radiotherapy, or the chemotherapy depending on the tumour type and the response. The window to preserve the ambulation is twenty-four to forty-eight hours. [7]

Synthesis (1 mark). The fellow who holds the prevention of the tumour lysis, the airway-first principle for the mediastinal mass, and the steroid-first principle for the cord compression has the framework that organises the whole family of the paediatric oncologic emergencies. [3]