Fournier’s gangrene (FG) is a very rare necrotizing fasciitis. Predisposing factors associated with FG include diabetes, alcoholism, immunosuppression, cytotoxic drugs, chronic use of steroids, smoking, lymphoproliferative diseases, malnutrition, and human immunodeficiency virus [1,2]. Its etiologies are determined in 75% to 100% of patients. The colon is the cause in 13% to 50% of patients and the genitourinary system in 17% to 87% of patients [3,4]. Other causes include skin infections and localized trauma. Colorectal causes include perianal abscesses, insertion of rectal instruments, perforation of the colon due to colorectal cancer, diverticulitis, hemorrhoids, and anal sex in homosexuals [5-7].

There is no clear algorithm for the treatment of FG-induced rectal cancer. However, early aggressive extensive debridement and surgery are recommended to remove the underlying rectal cancer. If the patient is elderly, septic, or hemodynamically unstable, it may be appropriate to perform an initial diversion procedure, followed by abdominoperineal resection (APR). We present a rare case in which FG was diagnosed on physical examination of a patient who came to the emergency department with generalized weakness and was diagnosed with rectal cancer subsequently during the etiologic differentiation of FG.

A 58-year-old male came to the emergency department with symptoms suggestive of weakness. He had a medical history of hypertension and diabetes mellitus, for which he was currently receiving treatment, and had no surgical history. In the previous month, the patient had been confined to bed, consumed minimal food, and experienced weight loss. The patient also reported constipation and anal pain. His blood pressure was recorded at 92/62 mmHg, heart rate at 93 beats per minutes, body temperature at 36.8℃, and respiratory rate at 18 breaths per min upon admission. Physical examination revealed ecchymosis around the perianal region, extending to the buttocks. The pelvic bone was palpated, and an anal opening was observed at 7 o’clock position, which exposed the protruding mass (Fig. 1). A digital rectal examination revealed a nodular mass that was palpated 12 cm from the anal version. Laboratory results indicated an elevated white blood cell count of 18,750/μL, hemoglobin level of 8.1 g/dl, CRP level of 18.97 mg/L, procalcitonin level of 1.24 ng/ml, CEA level of 13.5 ng/ml, and increased PIVKII level of 604.6. Computed tomography (CT) of the abdomen and pelvis showed an irregular thickening of the segmental rectal wall, which extensively invaded the perirectal area and prostate (T4b) (Fig. 2A). A perforation was observed in a part of the perirectal wall and a perineal air bubble was observed (Fig. 2B). Furthermore, subtle low attenuation lesions measuring < 2 cm were observed in both liver lobes (M1a) (Fig. 2C).

Figure 1. This figure illustrates the clinical presentation of a perianal lesion, including skin redness and spontaneous bleeding extending from the perianal region to the buttocks. An anal opening is visible at the 7 o’clock position, revealing a protruding mass.

Figure 2. (A) Computed tomography of the abdomen and pelvis showed an irregular thickening of the segmental rectal wall, which extensively invaded the perirectal area and prostate (T4b). (B) Presence of wall perforation, accompanied by the occurrence of perirectal and perineal air-bubbles. (C) Low-attenuated lesions measuring less than 2 cm, detected in both liver lobes. These findings suggest the presence of liver metastases (M1a).

We diagnosed a case of rectal cancer with distant metastasis to the liver, along with FG resulting from cancer perforation. Based on clinical evaluation, we decided to prioritize FG control before starting cancer treatment. The surgeons performed a laparoscopic diverting loop ileostomy to prevent stool contamination of the FG lesion through the fistula. We discussed with the plastic surgeon the possibility of extensive debridement of necrotic tissue from the FG, but ultimately decided against debridement instead of managing the wound with a betadine-soaked dressing and prescribing antibiotics. During hospitalization, there were several changes to the antibiotic regimen. Starting on March 19, 2022, after being diagnosed with FG, the patient was treated with vancomycin and meropenem. Following wound culture results that identified an ESBL-negative organism, the antibiotic treatment was switched on April 2 to ciprofloxacin 400 mg twice daily. Due to symptoms of fever on April 9, tazobactam/piperacillin combination 4.5 g three times daily was added to her regimen. On April 22, a consult was made with the department of infectious diseases, leading to a step-down in her antibiotic treatment to ampicillin/sulbactam combination 3 g three times daily. With wound dressing and antibiotics, FG lesions improved from the first time (Fig. 3).

Figure 3. The wound associated with Fournier’s gangrene showed signs of improvement after the application of betadine soaking dressing and antibiotics, as compared to its initial state.

Histological examination of the extruding mass revealed a moderately differentiated adenocarcinoma with positive EGFR expression. No mutations were detected in KRAS, NRAS or BRAF, which were all found to be wild-type. Given the T4bNxM1a stage of the rectal cancer, initiation of systemic chemotherapy was considered. However, due to the patient’s severe comorbidities and poor performance status, which is Eastern Cooperative Oncology Group performance status 4, the treatment was expected to be difficult to tolerate. Consequently, the therapeutic approach has changed to palliative care. The primary treatment was definitive radiotherapy with a total dose of 60 Gy in 24 fractions to reduce the size of the tumor. After radiotherapy, the patient had CT scans for follow-up. Rectal cancer, which was targeted by radiotherapy, showed a partial response, but liver metastases continued to progress (Fig. 4A, 4B). As the patient’s infection condition stabilized and his overall physical condition showed signs of improvement, systemic chemotherapy was deemed appropriate. Bevacizumab-FOLFOX treatment was initiated, given the potential for skin toxicity associated with cetuximab. Fortunately, the patient responded positively to systemic chemotherapy and received 13 cycles of anticancer therapy. Follow-up CT scans consistently showed a partial response to treatment (Fig. 5).

Figure 4. (A) The size of the target lesion, representing rectal cancer, exhibited a decrease on the abdominal pelvic computed tomography follow-up conducted post-radiotherapy. (B) Metastatic lesions in the liver exhibited a progression state.

Figure 5. The sequential abdominal pelvic computed tomography scans conducted after the 3rd, 6th, 10th, and 12th cycles of chemotherapy consistently demonstrated partial response of the cancer, indicating a favorable therapeutic outcome.

FG is a very rare condition, with an estimated incidence of 1.6 per 100,000 in males [8]. Although there are no precise statistical data on the incidence of FG induced by rectal cancer, an analysis of 23 patients diagnosed with FG between 1988 and 2014 found that rectal cancer accounted for 1.47% to 16.6% of all cases of FG [9]. There are several reasonable explanations for the rarity of FG induced by rectal cancer. One of these is improved access to healthcare as the social and economic environment improves.

Early symptoms of FG include fever, swelling, and erythema. These nonspecific symptoms can be mistaken for cellulitis or abscesses, which can delay an accurate diagnosis. CT is widely considered the most effective diagnostic tool to identify gangrene, localize the source of infection, and estimate the spread of the disease [10]. In patients with FG, CT scans typically reveal soft tissue thickening, inflammation, and subcutaneous emphysema.

Paty and Smith [11] stated that the mortality rate of FG can be effectively reduced through a combination of intensive care, appropriate antibiotic therapy, and surgical intervention, emphasizing the necessity of a multidisciplinary approach in managing the condition. Treatment of patients with FG-induced rectal cancer is complicated. Clinicians make treatment decisions based on the social and economic circumstances of patients, as well as the wishes of the patient and their caregivers, which inevitably involves clinician subjectivity. The patient had rectal cancer with liver metastases and was treated with systemic chemotherapy. However, we decided that this was a palliative care indication, given the patient’s poor performance status and comorbidities of infection due to FG [12]. We decided first to try radiotherapy to reduce tumor burden and then systemic chemotherapy if the patient’s comorbidities improved.

Histological examination revealed adenocarcinoma without KRAS, NRAS, and BRAF mutations. In this case, cetuximab could have been considered a systemic chemotherapy regimen [13]. However, we started primary chemotherapy with the bevacizumab-FOLFOX regimen due to the skin toxicity that can occur with cetuximab treatment. Skin toxicity may occur in more than 10% of patients treated with cetuximab and is particularly common in patients with good response. The most common adverse reaction is an acne-like rash, and other side effects may include dry skin, fissures, anaphylactic infusion reactions, telangiectasias, hyperpigmentation, and hair changes [14-18].

Fortunately, the patient responded positively to chemotherapy and had a partial response. However, the patient’s systemic infection is still uncontrolled, and pus continues to drain from the dead space of the FG wound. Treatment of the wound and the administration of antibiotics are insufficient because wound infections originate from rectal cancer. Surgical intervention to remove cancer, such as APR, is essential for the treatment of FG secondary to rectal cancer infiltration. We discussed this issue with the surgical team, and it was decided that surgery would be considered after an improvement in the systemic infection following antibiotic treatment. Mortality from all causes of FG is approximately 21% (ranging from 7% to 75%), which is similar to mortality of 22% before the use of antibiotics [19]. This suggests that antibiotic therapy is not the main treatment for FG and that prompt and aggressive surgical treatment is more important.

In summary, we report a case of FG induced by perforation of rectal cancer diagnosed at the first visit. This condition is rare and has a poor prognosis. We emphasize the importance of early diagnosis of FG as a complication and prompt surgical intervention.

None.

No potential conflict of interest relevant to this article was reported.

Conceptualization: Jong Yoon Lee, Hye Ryeon Kim. Data curation: Chi Hyeon Choi. Formal Analysis: Chi Hyeon Choi. Project administration: Chi Hyeon Choi, Jong Yoon Lee, Hye Ryeon Kim. Supervision: Jong Yoon Lee. Validation: Jong Yoon Lee. Writing – original draft: Chi Hyeon Choi. Writing – review & editing: Chi Hyeon Choi, Dong Wook Kim, Jong Yoon Lee, Jong Hoon Lee.