Inflammatory Myofibroblastic Tumor Arising in the Cul-De-Sac, Mimicking Ectopic Decidua

Extra-ovarian neoplasms incidentally discovered during cesarean section are very rare. Here we report a case of inflammatory myofibroblastic tumor found during cesarean section of a 30-year-old, full-term woman, forming a mass in her cul-de-sac. Histology revealed an extensively decidualized spindle cell process, positive for anaplastic large cell lymphoma kinase (ALK) through immunohistochemistry and fluorescent in situ hybridization (FISH). To the best of our knowledge, this is the first presentation of inflammatory myofibroblastic tumor in this location without concurrent intrauterine component, that additionally demonstrates this degree of decidualization, mimicking ectopic decidua.