EML4-ALK-positive non-small cell lung cancer in a patient treated with azathioprine for ulcerative colitis.

EML4-ALK-positive lung cancer is a novel cancer entity associated with light or never smoking, younger age, and adenocarcinoma with acinar or signet-ring cell type histology. Another mutation of ALK with NPM, resulting in NPM-ALK fusion mutation, was described in patients with anaplastic large cell lymphoma (ALCL). It was subsequently reported in organ transplant recipients and patiens undergoing immunosuppressive therapy. We describe a case of lung cancer in a 36-year-old nonsmoking woman with ulcerative colitis treated with azathioprine, who was diagnosed with EML4-ALK-positive, metastatic lung cancer two months postpartum. Crizotinib 300 mg/day has been effective in maintaining response after chemotherapy failed. The resemblance of this case to ALK-positive ALCL in organ transplant recipients suggests that similar mechanisms may be responsible for the development of both ALK-positive lung cancer and ALCL in patients receiving immunosuppressive therapy.