Concurrent pulmonary hypoplasia and congenital lobar emphysema in a young dog with tension pneumothorax: a rare congenital pulmonary anomaly

BACKGROUND: Pulmonary hypoplasia (PH) and congenital lobar emphysema (CLE) are very rare congenital pulmonary anomalies in veterinary medicine. PH refers to the incomplete pulmonary development due to embryologic imbalance of bronchial development between the lung buds, while CLE is defined as alveolar hyperinflation due to bronchial collapse during expiration caused by bronchial cartilage dysplasia, external bronchial compression, and idiopathic etiology. CLE may develop into pulmonary blebs or bullae that may rupture and induce a spontaneous pneumothorax. There are no reports on concurrent PH and CLE in animals. CASE PRESENTATION: A 7-month-old castrated male Italian Greyhound weighing 5.5 kg presented with vomiting and acute onset of severe dyspnea without any previous history of disease. After emergency treatment including oxygen supplementation and thoracocentesis, plain radiology and computed tomography scanning were performed and lobar emphysema with multiple bullae in the left cranial lung lobe associated with tension pneumothorax was identified. Since the pneumothorax was not resolved despite continuous suction of intrathoracic air for 3 days, a complete lobectomy of the left cranial lung lobe was performed. The excised lobe was not grossly divided into cranial and caudal parts, but a tissue mass less than 1 cm in size was present at the hilum and cranial to the excised lobe. Postoperatively, the dog recovered rapidly without air retention in the thoracic cavity. Histopathologically, the mass was identified as a hypoplastic lung tissue with collapsed alveoli, bronchial dysplasia, and pulmonary arterial hypertrophy. Additionally, the excised lung lobe presented CLE with marked ectasia of alveoli, various blebs and bullae, and general bronchial cartilage dysplasia. According to gross and histopathologic findings, the dog was diagnosed with concurrent PH and CLE in the left cranial lung lobe. During 16 months of follow-up, the dog was well and without any respiratory problems. CONCLUSIONS: This case report confirmed the clinical and histologic features of two different types of rare congenital pulmonary anomalies, PH and CLE, which occurred concurrently in a single lung lobe of a young dog. The condition was successfully managed with lobectomy.