Atypical Presentation of Retroperitoneal Fibrosis Causing Colonic Obstruction: A Case Report.

Retroperitoneal fibrosis (RPF), also referred to as Ormond's disease, is a rare fibroinflammatory condition characterized by abnormal fibrous tissue deposition in the retroperitoneal space, which traditionally presents with ureteral obstruction. Nonetheless, our case report showcases an exceptional instance involving a 70-year-old female patient who presented with symptoms suggestive of colonic obstruction, an unusual presentation that is not commonly associated with RPF. Although RPF has established associations with autoimmune conditions such as immunoglobulin G4-related disease and systemic lupus erythematosus, its connection to colonic obstruction remains undocumented in the medical literature. Our patient is a 70-year-old female who presented with constipation, anemia, and fecal occult blood. Her past medical history included a hysterectomy due to fibroids, right breast lumpectomy, type 2 diabetes mellitus, subclinical hyperthyroidism, hypertension, and obesity. Upon physical examination, the patient's abdomen appeared protuberant but was non-tender to palpation. Bowel sounds were normal, and there was no distension. Notably, there was no tenderness in the right or left costovertebral angles, nor was there any guarding. Workup with colonoscopy could not be completed due to the inability to pass a colonoscope beyond the rectosigmoid junction. Further workup with barium enema confirmed an apple core lesion seen in the rectosigmoid concerning for a neoplastic or inflammatory process. Finally, a computed tomography scan of the abdomen and pelvis showed a 7.1 cm right pelvic mass attached to the bladder and cecum, moderate right hydroureteronephrosis, and a 5.2 cm left adnexal mass with soft tissue changes narrowing the sigmoid colon. The next step was to take the patient for an exploratory laparotomy. During exploratory laparotomy, extensive adhesions and desmoplastic reactions were observed in the pelvic region, involving the sigmoid colon, bladder, cecum, and appendix. Two firm masses were identified in the retroperitoneum, one located in the left lower quadrant (LLQ) adherent to the posterior wall of the sigmoid colon and one in the right lower quadrant (RLQ) adherent to the posterior wall of the cecum. Three specimens were sent to pathology for further examination: a portion of the sigmoid colon, a resection from the RLQ mass, and a resection from the LLQ mass. Pathology reported dense fibrotic masses with abscess-like formation, reactive in nature and of unclear etiology, and negative for malignancy. They were negative for fibromatosis (β-catenin negative), and IgG4+/IgG+ was approximately 5%. Interestingly, the LLQ mass also contained remnants of the fallopian tube and ovary and benign cystic changes. This case report presents a unique and atypical presentation of RPF, deviating from the conventional presentation of ureteral obstruction. The patient's initial symptoms suggested colonic obstruction, a clinical scenario rarely linked to RPF. This case underscores the significance of considering diverse clinical presentations when diagnosing RPF, thereby expanding our comprehension of the condition's clinical spectrum and ultimately refining patient care and management.