Severe Fournier’s gangrene in a patient with rectal cancer: case report and literature review

Background Fournier’s gangrene in the setting of rectal cancer is rare. Treatment for Fournier’s gangrene associated with rectal cancer is more complex than other cases of Fournier’s gangrene. We report on a patient with severe Fournier’s gangrene in the setting of locally advanced rectal cancer who was treated with a combined modality therapy. Case presentation A 65-year-old man presented with general fatigue and anal pain. The medical and surgical histories were unremarkable. A black spot on the perineal skin surrounded by erythema was found on physical examination, suspicious for Fournier’s gangrene. Computed tomography scan showed a rectal tumor invading into the bladder (clinically T4bN2M0) and abscess formation with emphysema around the rectum. He was thus diagnosed with locally advanced rectal cancer and Fournier’s gangrene with a severity index score of 12 points. We created a diverting loop colostomy of the transverse colon and performed extensive debridement of the perineum and perianal area. Fifty days later, the patient underwent radical total pelvic exenteration with sacrectomy. In addition, reconstruction of the soft tissue defect was performed using the rectus muscle, the gluteus maximus muscle, and the femoral muscle. Histopathological findings of the specimen were as follows: the tumor was a moderately adenocarcinoma with invasion to the bladder and the prostate (T4b), metastases to four resected lymph nodes (N2), and lymphovascular invasion. There were no major postoperative complications, and the patient was discharged 108 days postoperatively. Conclusions We report a rare case of locally invasive rectal cancer associated with Fournier’s gangrene. This case highlights a usual cause of Fournier’s gangrene. Physicians should be cognizant not only of the more common condition but also of the rare presentations including those associated with rectal cancer.


Background
Fournier's gangrene (FG) is necrotizing fasciitis and commonly begins without trauma or urinary tract disease. FG in the setting of rectal cancer is rare. A specific risk factor is rectal cancer perforation. Treatment includes extensive debridement of the areas of necrosis and the administration of broad-spectrum intravenous antibiotics. In the setting of rectal cancer, the causative rectal tumor should be removed, but the timing of this is a complex clinical decision.
We report on a patient with severe FG in the setting of locally advanced rectal cancer who was treated with a combined modality therapy.

Case presentation
A 65-year-old man was brought to our outpatient hospital in an ambulance complaining of general fatigue and anal pain. The medical and surgical histories were unremarkable. His initial body temperature was 95.7°F, blood pressure was 125/58 mmHg, heart rate was 92 beats/min, and oxygen saturation was 98 % on room air. On physical examination, a black spot on the perineal skin surrounded by erythema was found. Due to a clinical suspicion for FG, a computed tomography (CT) scan and blood tests were obtained urgently (Fig. 1). CT scan showed abscess formation with emphysema around the rectum, as well as a tumor invading the bladder (cT4b) with some lymph node metastases in the mesorectum (cN2); there was no evidence of distant metastasis (M0) (Fig. 2). Blood tests were remarkable for a hemoglobin of 3.2 g/dl and a leukocytosis of 63,200/μl. The patient was thus diagnosed with locally advanced rectal cancer and FG with a severity index score of 12 points [1]. Urgent diverting colostomy of the transverse colon and extensive debridement of the perineal area were performed (Fig. 3). Biopsies taken previously revealed a moderately differentiated adenocarcinoma.
The patient received nutritional support after surgery. Follow-up CT scan after the surgery showed no new lesions, so we performed a radical total pelvic exenteration (TPE) with sacrectomy 50 days after the initial surgery. For the urinary diversion, Bricker's operation was performed (Fig. 4). In addition, reconstruction of the soft tissue defect was performed using the rectus muscle, the gluteus maximus muscle, and the femoral muscle (Fig. 5). Histopathological findings of the specimen were as follows: the tumor was a moderate adenocarcinoma with invasion to the bladder and the prostate (T4b), metastases to four resected lymph nodes (N2), and lymphovascular invasion. There were no major postoperative complications, and the patient was discharged on postoperative day 108.

Discussion
Although perforation of rectal cancer after treatment with bevacizumab or radiation therapy has been well documented, reports of spontaneous perforation of rectal cancer presenting as FG are rare. There were 23 cases evaluated in a review by Bruketa et al. [2]; in Japan, 17 cases including the present case have been reported ( Table 1). The median age in the Japanese group was 58 (range, 30-80) years with a male to female ratio of 15:2. Six (35 %) of 17 patients had diabetes mellitus (DM) as a comorbidity. DM was considered a risk factor for FG in the Japanese group as well. Colostomy was created in 9 of 17 patients. Treatment for rectal cancer with FG was abdominoperineal resection (APR) for six patients, TPE for three patients, and chemotherapy alone for three patients. Four patients were followed conservatively without treatment. Regarding long-term prognosis of the patients, survival of 4 years and 7 months was obtained in one patient who underwent APR, and the survival of the other 16 patients was not given. In this patient, we performed TPE with sacrectomy to obtain a negative resection margin, resulting in a good oncological outcome. In addition, reconstruction was performed using the rectus muscle, the gluteus maximus muscles, and the femoral muscle. There were no major postoperative complications, and the patient was discharged on postoperative day 108.
The mortality of FG is high, frequently due to a delay in the diagnosis and management. The interesting report Fig. 1 The appearance of the patient's perineum. A black spot and emphysema were found in the perineal skin about the metabolic evaluation of FG was reported by Surucu et al. [3]. They showed the significance of 18 F-fluorodeoxyglucose positron emission tomography for FG in metabolic levels before the visual changes occurred. The mortality of FG in the setting of rectal cancer is not clear. The most common causes of death in FG are sepsis and multiple organ failure. Prognostic predictions can be based on Fournier's gangrene severity index (FGSI), comprised of the following: body temperature, heart rate, respiratory rate, and serum level of sodium, potassium, creatinine, and bicarbonate, as well as hematocrit value and leukocyte count [1]. Laor et al. [1] stated that a score of >9 was associated with a 75 % mortality, while a score   of ≤9 corresponded to a 78 % probability of survival. While our patient presented with an FGSI score of 12 points, we managed to treat the patient without a major complication. Recently, hyperbaric oxygen (HBO) has been recommended as an additional therapy for patients with FG because HBO inhibits the growth of anaerobic bacteria in the affected tissues, prevents further extension of tissue necrosis, and reduces systemic toxicity [4,5]. Actually, for this patient creating colostomy as an initial procedure, early radical debridement of necrotic tissues, drainage, and antibiotic therapy were effective to manage severe FG in the setting of rectal cancer. Although TPE with sacrectomy was required to obtain a negative resection margin, we could get a good outcome. Although adjuvant therapy was required because of locally advanced rectal cancer of pathologically T4b N2 M0, the patient was followed up at the outpatient section of our institution without adjuvant therapy until all wound had healed completely. Unfortunately, we suspected that local recurrence developed in the perineal wound because of an abdominal 18 F-fluorodeoxyglucose positron emission tomography in 5 months after curative TPE (Fig. 6). The patient died of primary disease 1 year after prior surgery.

Conclusions
Aggressive debridement, broad-spectrum antibiotics, and intensive supportive care are critical for the management of FG. Although colorectal cancer has previously been reported as a cause of FG, it remains an extremely rare phenomenon.