Four patients with right middle lobe hypoplasia complicated by primary lung cancer

Abstract

[Introduction] Lung hypoplasia causes respiratory disturbances during the neonatal period; however, in rare cases, it may be detected during adulthood and can accompany malignant tumors. [Cases] We encountered four patients with right middle lobe hypoplasia complicated by lung cancer. They were three men and one woman, and all were in their sixties. CT volumetry revealed that the average rate of the middle lobe volume to whole lung one was 0.24%. Based on histological analyses, the diagnoses were typical carcinoid in three patients and small cell lung cancer in one patient. All four patients underwent right middle lobe resection. [Discussion] Although lung hypoplasia is typically secondary to a congenital abnormality, the four patients reported here had primary pulmonary hypoplasia with no complications, and the lesions were exclusively found in the right middle lobe. This may be the reason why the patients had not experienced any respiratory disturbances until adulthood. Although all patients had neuroendocrine tumors, the causal relationship between lung hypoplasia and neuroendocrine tumors is unknown. [Conclusion] We treated four patients with right middle lobe hypoplasia complicated by lung cancer.