Spontaneous tumour regression is a well-recognised phenomenon in infantile favourable-biology neuroblastoma. An ‘expectant-observation’ strategy avoids chemotherapy or surgery associated risks but has mostly been limited to small tumours (diameter < 5 cm) and discontinued if significant tumour growth or increasing catecholamine levels. Here we report the successful use of an observation-only strategy in an infant with unresectable neuroblastoma > 5 cm at diagnosis which initially tripled in size with a 10-fold increase in urinary catecholamines. We highlight the need for consensus evidence-based criteria to define the subgroup where a ‘wait-and-see’ approach is appropriate and criteria to begin active treatment.

Congenital pulmonary airway malformation (CPAM), previously known as congenital cystic adenomatoid malformation (CCAM), is a rare developmental lung abnormality with the potential for malignant transformation. Bronchioloalveolar carcinoma (BAC), pleuropulmonary blastoma (PPB), rhabdomyomatous dysplasia/rhabdomyosarcoma (RMS) have been associated with CPAM. We report an unusual case of a 1-day-old male newborn who underwent lobectomy for a cystic lung lesion, which was found to be a mucinous BAC with K-ras mutation in a type 1 CPAM. The case supports the relationship between type 1 CPAM and BAC/KRAS mutant, and highlights that the malignant transformation can occur in very early stage of the infancy.