Acute Exacerbation of Dermatomyositis-Associated Interstitial Pneumonia after Resection of the Descending Colon Cancer Requiring Differential Diagnosis from Anastomotic Leakage

A 65-year-old man presented with muscle pain and finger swelling, and was given a diagnosis of anti-MDA5 antibody-positive dermatomyositis and interstitial pneumonia. Colonoscopy, as a detailed examination for malignancy detected descending colon cancer (cStage IIIa), and laparoscopic left hemicolectomy was performed. On postoperative day 4, hypoxemia developed and acute exacerbation of the interstitial pneumonia was diagnosed. We started steroid pulse therapy with cyclosporin A and cyclophosphamide. On postoperative day 7, he developed abdominal pain. CT revealed retroperitoneal and intra-abdominal gas. We considered the possibility of anastomotic leakage, nevertheless, there was no tenderness or change in vital signs. We diagnosed this as intra-abdominal gas spreading from mediastinal emphysema and gave conservative treatment with antibiotics. The clinical course was uneventful and the patient was discharged on postoperative day 41. Anti-MDA5 antibody-positive dermatomyositis is often associated with rapidly progressive interstitial lung disease. Surgical cases for malignancy with this disease should be carefully treated.