S2104 Rectal Adenocarcinoma Presenting as a Perirectal Abscess

Introduction: Colorectal cancer (CRC) is the third leading cause of cancer-related mortality. Despite excellent screening efforts resulting in the decrease of the overall incidence and mortality rate of CRC, the incidence is rising among younger adults. Rectal cancer (RC), specifically, disproportionately affects this younger population. Classic symptoms of RC such as hematochezia, tenesmus, rectal pain, and bowel habit changes are well known but can be non-specific and misdiagnosed. Rare presentations in combination with these conventional symptoms can occur warranting a higher degree of clinical suspicion. Here we report a case of rectal adenocarcinoma (RA) presenting as a perirectal abscess. Case Description/Methods: A 52-year-old male with uncontrolled type 2 diabetes presented with a 5-day history of fatigue, subjective fever as well as swelling and cramping pain around the left buttocks. In addition to weight loss, he reported a 2-2.5 year and 2-month history of rectal bleeding and changes in bowel habits, respectively, which were attributed to other conditions including hemorrhoids and IBS. He had never undergone a colonoscopy. On exam, the patient was afebrile (36.1°C), tachycardic (110 bpm), hypotensive (83/55 mmHg), and tachypneic (20 breaths/min). His left buttock was swollen, indurated, and tender on palpation but there was no gross fluctuance or crepitus. WBC count (33.6 × 109/L), and lactate (4.2 mmol/L) were elevated suggesting severe sepsis. CT abdomen/pelvis and examination in the OR for suspected, and subsequently confirmed, Fournier’s gangrene and perirectal abscess led to the discovery of a RA (final: pT4N0M0, stage IIB/C). Management included surgical debridements, antibiotic therapy, neoadjuvant chemoradiation, and abdominoperineal resection. He remains in remission with a stable CEA level and unremarkable follow-up colonoscopies. Discussion: While uncommon, RC disproportionately affects younger patients where the annual incidence has increased by 2.1% in this group. The conventional presentation of RC may be attributed to a different condition, especially in younger patients, delaying diagnostic colonoscopy and treatment. In the literature, 4 cases of RA presenting as perirectal abscess in adults have been described where 2 patients were 45 years old or younger. In all cases, the perirectal abscess was diagnosed before or concurrently with the RA. Taken together, perirectal abscess, especially if present in conjunction with classic RC symptomology, may necessitate the workup of RC.