Don’t forget mediastinal masses

O’Carroll et al highlight some of the important issues in childhood asthma unresponsive to simple treatment in primary care.¹ However, they omit malignancy from their differential diagnoses, missing an essential learning point—that chest radiography is advised in children failing to respond to simple standard asthma treatment and certainly before starting oral steroids. Chest radiography should also be performed if the diagnosis is uncertain or if asthma symptoms change.²

Rarely, childhood leukaemia or lymphoma presents with symptoms of asthma—progressive airway obstruction secondary to external lymph node compression causes wheeze and shortness of breath. At worst, this proceeds to critical airway compression and respiratory arrest.² Standard asthma treatment (steps 1 or 2 of the British Thoracic Society’s asthma guidelines)³ may provide a partial clinical response, but deterioration will ensue. At this point, chest radiography, if performed, will show a mediastinal mass.

The National Institute for Health and Clinical Excellence guidelines for referral for suspected cancer clearly state that “shortness of breath is a symptom that can indicate chest involvement but may be confused with conditions such as asthma.”⁴ Clinicians should always be aware that malignancy can present with respiratory symptoms.

Giving oral steroids to a child with undiagnosed leukaemia or lymphoma is risky. Tumour lysis syndrome may be precipitated and these patients may present to hospital in renal failure. Moreover, such pretreatment may make subtype diagnosis and disease staging difficult to perform, further compromising the ability to provide these patients with the best treatment. Most worryingly, pretreatment with oral steroids in childhood malignancy is associated with adverse outcome.⁵