Teaching Case

A 70-year-old male with a seven-year history of pseudomyxoma peritonei (PMP) was referred for gastroenterological evaluation because of a mid-abdominal chronic cutaneous ulcer producing a mixture of clear, gelatinous and light brown, foul-smelling output (Figure 1). The cutaneous ulcer had been present for three years.

The patient was referred to fluoroscopy as an abdominal fistula was suspected. Fluoroscopy images obtained after injection of 100 ml iohexol contrast through a 14CH Foley catheter in the cutaneous fistula showed contrast passing into the closed-off descending colon, through an entero-colic fistula. The fluoroscopy also revealed contrast in the upper left quadrant, above the left colonic flexure (Figure 2).

The fluoroscopy was followed by an abdominal CT without additional contrast injections, as the purpose of the CT was to better assess the distribution of the contrast agent administered during the fluoroscopy (Figure/video 7). In addition to a large quantity of lobulated ascites, it revealed a cutaneous fistula in the abdominal midline communicating with the small intestine, which in turn communicated with the large intestine (Figures 3a and 3b). From the left colonic flexure, another fistula crossed the diaphragm into the pleural space of the left costophrenic recess (Figures 4a and 4b). From the pleural space, the contrast continued further up through the lower branches of the left lower lobe bronchi (Figure 5). Two months later, a CT with intravenous contrast still showed mucinous intra-pleural masses (Figure 6 and Figure/video 8).

Background

Pseudomyxoma peritonei is a rare condition (annual incidence of 0.2 to 2:1,000,000) where mucin-producing adenomas or adenocarcinomas—most often from the appendix—rupture and mucin-producing endothelial cells implant on the peritoneal surfaces [1]. The large masses of gelatinous mucin produced by the PMP cells give rise to intraabdominal complications such as bowel obstruction. Other complications include fistulas and nutritional impairment. PMP is not considered an invasive disease, and in most cases, it does not spread outside the peritoneal cavity [1]. Rare cases of intrathoracic spread have been reported, usually due to iatrogenic perforation of the diaphragm during combination of complete cytoreduction surgery and hyperthermic intraperitoneal chemotherapy (HIPEC) [2,3].

Imaging Perspective

The “classic” signs of PMP on abdominal CT are large amounts of intraperitoneal low attenuation ascites, as the mucin has a similar density as water. “Scalloping” around the liver and spleen can distinguish PMP from regular intraperitoneal fluid ascites. Differentiating PMP from peritoneal mesothelioma and peritoneal carcinosis can be challenging, but the presence of soft tissue intraperitoneal nodules is more likely in carcinosis and mesothelioma. Furthermore,  a clinical history of asbestos exposure or pleural plaques could help differentiate mesothelioma from PMP. Internal fistulas in PMP are best visualised on CT with oral contrast, while cutaneous fistula is best visualised with direct injection of contrast into the fistula, followed by either fluoroscopy or CT. In patients showing clinical signs of fistulating PMP, the clinician and radiologist should discuss the optimal imaging technique to best identify the fistulas, including a combination of fluoroscopy and CT.

Outcome

In our case, the patient was diagnosed with PMP seven years earlier, where complete cytoreduction surgery, including appendectomy and splenectomy, was performed, followed by HIPEC. The diagnosis of pseudomyxoma peritonei was confirmed after multiple biopsies of the removed tissues, concluding with a low-grade mucinous tumour originating from the appendix. It was not classified further. He was free from symptoms for two years after initial surgery, but then developed ileus of the colon due to large PMP masses, resulting in an ileostomy. The cutaneous wound developed four years after the initial surgery, initially with clear mucinous output. After two years, the output changed to mixed mucin and faecal matter. Although the patient was treated for several pneumonias during the last five years, and was prone to coughing resulting in a foul taste in his mouth, no one suspected pleural involvement of PMP.

Fistula development is a rare complication of PMP. Cutaneous fistulas should be suspected if patients develop chronic abdominal wounds. Intra-abdominal fistulas can present as sudden faecal output in patients with ileostomy, or, in our case, as sudden faecal output in a pre-existing cutaneous fistula. Pleural fistulas should be suspected in PMP patients with recurrent pneumoniae, even years after surgery.

The treatment possibilities in patients with fistulating PMP are sparse. In our case, the patient was offered parenteral nutrition in an attempt to dry out the intraabdominal and cutaneous fistulas. Due to extensive disease progression, there were no treatment options for the pleural involvement. In other cases, intra-pleural HIPEC could be a possible treatment option [4,5].

Take Home Message

Although the development of fistulas in PMP is a rare complication, it should be suspected in patients with recurring pneumonia, chronic cutaneous ulcers, malnutrition or unexplained faecal output after stoma surgery. A combination of imaging techniques might be required, and diagnosis and treatment should be performed in highly specialised centres.

Written informed patient consent for publication has been obtained.