Opioid toxicity with underlying tumour lysis syndrome in a patient with CMML: a diagnostic and therapeutic challenge.

Use of strong opioids like morphine as analgesics for painful conditions in haematological malignancies is a challenging task. We report a unique case of chronic myelomonocytic leukaemia presenting with opioid toxicity overlapping with tumour lysis syndrome. The patient was on hydroxyurea-based chemotherapy for the primary disease. She was receiving oral morphine for abdominal pain due to splenomegaly. She was brought to the emergency in unresponsive state with pinpoint pupils. Opioid overdose leading to unconsciousness was suspected as the first diagnosis. Further workup revealed a final diagnosis of tumour lysis syndrome overlapping with opioid overdose. The patient was ventilated and started on naloxone infusion, and supportive measures for managing tumour lysis were added. The patient gradually improved and was extubated on the fifth day of ventilation. This case presents several learning points for the treating physician. Haematological malignancies have a dynamic course of disease with waxing and waning tumour burden during the course of chemotherapy. This fact should be kept in mind when prescribing strong opioids like morphine on outpatient basis to these patients. Massive tumour cell lysis during the course of chemotherapy may precipitate tumour lysis syndrome and may lead to renal dysfunction which makes the patient susceptible to morphine-related adverse effects. Pain physician should keep a watch for therapy-related adverse effects to avoid diagnostic and therapeutic dilemma associated with coexisting features of these two fatal conditions.