Reactive Nodular Fibrous Pseudotumor: Case Report and Review of the Literature

We will describe a case of a patient diagnosed with a rare identity of a benign lesion, “reactive nodular fibrous pseudotumor” (RNFP). It is a tumor which preoperatively can present as a malignant tumor and is only reported in 19 cases. According to the very limited amount of information on this tumor in the literature it is mostly seen after trauma or intraperitoneal inflammation. Our case is the second one of RNFP associated with endometriosis, which is a frequently seen intraperitoneal inflammation process in women. Knowledge that these large pseudotumoral lesions can occur is important to direct the management of these patients. 1. Introduction A multitude of tumors can occur in the peritoneal cavity. Correct diagnosis is of paramount importance for proper treatment. We recently observed a patient with an intra-abdominal mass, diagnosed histopathologically as “reactive nodular fibrous pseudotumor” (RNFP). This is a benign lesion, often mimicking a malignant tumor preoperatively. The pathogenesis might be related to intraperitoneal “trauma” such as endometriosis. It is previously reported in only 19 cases. 2. A Case Report A 45-year-old woman was hospitalized in another hospital, because of intractable menometrorrhagia, pain, and gradual abdominal swelling. A vaginal hysterectomy was planned and performed but shortly had to be stopped because of bleeding. During the procedure intraperitoneal lesions were seen and biopsied. Pathology shows no signs of malignancy. Afterwards the patient was sent to our hospital for further diagnosis. Her medical history mentioned no other abdominal surgery, migraine headaches, or other major incidents. Her obstetrical history recorded an uncomplicated vaginal delivery. Clinical examination showed no particularities. Biochemically we found no abnormalities and serum CA125 levels were normal. Gynecological ultrasound (Figure 1) demonstrated not only diffuse uterine adenomyosis and myomas, but also multiple solid masses in the Douglas pouch, attached to the left ovary and rectosigmoid but without invasion of its muscular wall. MRI (Figures 2, 3, and 4) and CT (Figure 5) confirmed the presence of solid and strongly hypovascular masses in the pouch of Douglas. A similar smaller lesion was present at the caudal border of the transverse colon. The very low signal intensity on T1- and T2-weighted MR images was very suggestive for fibrotic tissue. On imaging the diagnosis of disseminated intraperitoneal leiomyomatosis was suggested, but other fibrous tumoral lesions or malignancy could not be excluded. Figure 1: Ultrasound: