26-year-old male referred to General Surgery after being diagnosed accidentally after an imaging test by the Digestive Service of a mass in the left diaphragmatic crura following admission due to a flare-up of IBD. Personal history: extrinsic bronchial asthma, Schonleich-Henoch purpura in childhood, ileal Crohn's disease diagnosed in 2004 and smoker. Physical examination revealed abdominal pain on palpation in the right flank related to his IBD process and no masses or megaliths were palpable. Computed tomography (CT) identified terminal ileum with thickened walls and signs of vascular proliferation in relation to Crohn's disease, in addition to a lesion measuring 7.6 x 4.4 cm with well-defined borders and low density with septate areas with greater enhancement in the left diaphragmatic crura. A CT-guided percutaneous puncture was performed and the anatomopathological result was reported as abundant necrotic material with numerous polymorphonucleated leukocytes and frequent histiocytes with negativity for malignant cells.
Mid laparotomy and access to the left infradiaphragmatic retroperitoneal cavity was performed with removal of the mass that was intimately attached to the adrenal gland, upper pole of the kidney and left diaphragm with excision of part of it and direct suture of the latter. The postoperative period evolved favourably and the patient was discharged on the 7th postoperative day without immediate complications.
The definitive anatomopathological report was of an irregular bronchogenic cyst of elastic consistency measuring 8 x 4 x 4 x 4 cm, cavitated and with a purulent appearance. The microscopic description was reported as cystic formation with lumina lined by simple pseudostratified columnar epithelium and ciliated cells. Scarce goblet cells. Isolated smooth muscle bundles. No evidence of malignancy.

