Prevalence of pulmonary sequestration accounts for up to 6.4% of all congenital pulmonary malformations. We report on a 40-year-old woman who underwent excision of an aberrant solid retroperitoneal mass in the left subdiaphragmatic area. The mass was identified to be an extralobar pulmonary sequestration. The diagnosis could be made without surgery by percutaneous tissue biopsy and imaging. We encourage keeping in mind pulmonary sequestration anomaly presenting as an aberrant retroperitoneal mass. The aim of this case report is to increase awareness about the condition and review the criteria for its definitive diagnosis and treatment.