Radiographic and computed tomographic features of a suspected congenital pulmonary airway malformation (CPAM) of the right middle lung lobe and secondary pneumonia in a dog

A 2‐year‐old Beagle presented for progressive tachypnoea, mild dyspnoea, vomiting and diarrhoea. Computed tomography (CT) and radiography of the thorax revealed a bilateral pneumothorax, a consolidated, mispositioned right middle lung lobe that had extensive, variably sized gas and fluid cavitations, and otherwise complete parenchymal consolidation with minimal parenchymal contrast enhancement. Possible CT diagnoses included a chronic lung lobe torsion or necrotising emphysematous pneumonia. Surgical excision confirmed an abnormal right middle lung lobe, encapsulated with thickened pleura, intact perfusion and some aeration of the largest bullae without definitive torsion. The submitted lung lobe was beige to grey and severely distorted. Histopathological analysis diagnosed lobar consolidation with numerous multi‐loculated cystic cavitations and surrounding oedema, fibrosis and inflammation, consistent with a suspected congenital pulmonary airway malformation (CPAM) and secondary pneumonia. Various forms of CPAM are recognised in people, but minimal information is available on the radiographic and CT appearance in the veterinary literature.