RESUMEN
Myofibroblastic tumor (MIT) is characterized by the infiltration of different organs, most commonly the lungs, with nodular lesions composed of myofibroblasts and inflammatory cells, which can be identified by specific patterns in the immunohistochemical studies. When it involves the peritoneum it is difficult to eradicate, tends to relapse and it has an invasive behavior, requiring its differentiation from peritoneal carcinomatosis. Treatment may be surgical excision, the use of non-steroidal anti-inflammatory drugs (NSAIDs) and glucocorticoids. We report a 30 years old female with an unremarkable medical history, presenting with abdominal pain and progressive abdominal distention. A CT scan revealed multiple peritoneal nodular lesions. A surgical biopsy was reported as a myofibroblast and inflammatory cell infiltrate. Immunohistochemical staining was consistent with MIT. Given the extensive involvement of the peritoneum surgical therapy was not considered appropriate and treatment with NSAID and glucocorticoids was started. No response was observed after 6 months, therefore infliximab therapy was started. After 10 months of follow-up the patient is well, returned to normal life, ascites improved and resolved and CT scan showed partial regression or stabilization of the lesions.