A case of appendiceal mucinous cystadenoma which presented as painless purulent umbilical discharge

Abstract

A 57-year-old obese, diabetic woman, presented with 1 day history of purulent umbilical discharge. She was vitally stable and afebrile. Abdominal examination revealed a full abdomen with purulent discharge from the umbilicus, swelling with erythema and induration surrounding the umbilicus. Lab tests were normal. Initial impression was abdominal wall abscess. Ultrasound showed subcutaneous fluid collection. Non-contrast CT showed collection and abdominal wall defect at the umbilicus. On exploration of the abscess cavity, there were two defects (umbilical and supraumbilical) with appendix protruding through the umbilical defect and a part of a small bowel and omentum adherent to the other defect. Wash was given, bowel and omentum were released and appendectomy was performed. Histopathology showed mucinous cystadenoma with periappendicitis. We would like to highlight the rare occurrence of an appendiceal mucinous cystadenoma in such a clinical presentation.

Background

One of the rare conditions of the appendix is mucinous cystadenoma which is associated with marked distension of the appendiceal lumen with mucin. This rare condition is found in 0.2%–0.3% of appendectomy specimens in Europe and the USA.^{1 2} The most frequent symptom that patients with appendiceal mucinous cystadenoma present with is right iliac fossa pain, similar to an acute appendicitis; however, around 25% of patients are asymptomatic and found incidentally on imaging or during surgery.^{3 4} They typically occur in middle age or older people, more often in women than in men.⁵ Reported complications of this condition include pseudomyxoma peritonei, intestinal intussusception, intestinal obstruction, extrinsic compression of the ureter and other pelvic structures and gastrointestinal bleeding. The worse among these complications is pseudomyxoma peritonei which occur as a result of either spontaneous or iatrogenic perforation of the appendix with subsequent spread of the neoplastic cells and mucin into the peritoneal cavity.⁶

In this case report, we are presenting a case of perforated mucinous cystadenoma within an umbilical hernia presented as painless purulent umbilical discharge. While several cases of appendiceal mucinous cystadenoma has been reported in the literature,^{7 8} with some with perforation,⁹ to our best of knowledge, no case with a similar presentation has been reported.

In this article, we would like to emphasise the importance of adequate preoperative imaging in patients presenting with abdominal wall abscess to exclude the involvement of intra-abdominal structures and would suggest that blind interventions for abdominal wall abscess should be avoided. Our aim here is to highlight the rare occurrence of an appendiceal mucinous cystadenoma in such clinical presentation.

Case presentation

A 57-year-old woman, known case of diabetes mellitus presented with 1 day history of foul smelling purulent umbilical discharge. There was no history of fever, abdominal pain, change in bowel habit, urinary symptoms or recent travelling. Patient had a history of upper respiratory tract infection 2 weeks prior to the presentation for which she completed a 5-day course of antibiotics. There was no history of any previous surgeries apart from lower segment caesarean section 19 years ago.

On physical examination, patient was obese, generally well and not in distress. Vitals were as follow: temperature 37.5°C, peripheral capillary oxygene saturation (SPO₂) 99%, blood pressure 170/80 mm Hg, heart rate 86 beats/min, respiratory rate 20 breaths/min and blood glucose 17.1 mmol/L. Examination of the abdomen revealed a distended abdomen with purulent discharge from the umbilicus, swelling with significant erythema and induration around the umbilicus, mainly in the superior region. Abdomen was soft, lax and non-tender. Other systemic examinations were unremarkable. The initial impression was a deep abdominal wall abscess and a decision to drain the abscess under general anaesthesia was taken.

Investigations

Laboratory investigation showed a white cell count of 8.1 (x10⁹/L), haemoglobin 11.4 g/L and platelet count 501 (x10⁹/L). Both urea/electrolytes and liver function test were within normal ranges.

Examination of the umbilical and periumbilical areas by using curvilinear and linear ultrasound probes showed a loculated turbid collection seated in the subcutaneous periumbilcal fat, roughly measuring 5×8×10 cm in dimensions (about 200 cc volume) surrounded by inflammatory changes in the form of subcutaneous fat aggregation and oedema (figure 1). However, the depth of the inflammatory changes could not be assessed adequately because the patient was obese; hence, a limited non-contrast CT was done including the area of concern which revealed presence of periumbilical anterior abdominal wall inflammatory changes with fat stranding and significant fluid collection.

Figure 1.

Axial ultrasound done using the curvilinear probe showed subcutaneous fluid in the periumblical region.

Extension of the inflammatory changes intraperitoneal with regional peritoneal fat stranding and adherence of small bowel segments to the regional posterior aspect of the abdominal wall (figure 2).

Figure 2.

subcutaneous fluid collection in the periumblical region (white arrow).

Pus culture was positive for Escherichia coli and Klebsiella pneumoniae (sensitive to the antibiotics she was on).

Histopathology of the resected appendix showed macroscopic features of size of appendix 5x1x1 CM surrounded by thick fat. Microscopic features of mucinous cystadenoma with low grade dysplasia (figure 3). Moderate mural fibrosis and heavy periappendiceal acute inflammatory cell infiltrate with abscess formation. Glandular epithelium seen in serosal surface with no invasive malignancy. Impression was mucinous cystadenoma with periappendicitis and abscess (Peritoneal Surface Oncology Group International (PSOGI) non-invasive neoplasms—low-grade appendiceal mucinous neoplasm (LAMN) and as per new American Joint Committe on Cancer (AJCC) classification—T4a)

Figure 3.

Low-power view (the left image) of the appendicular mass showing mucinous cystadenoma in the centre projecting towards the serosal surface (H&E stain). High-power microscopic view (the right image) of the tumour at the surface serosa showing glandular mucin-producing epithelium surrounded by mixed inflammatory cell infiltrate (H&E stain).

Differential diagnosis

Our first diagnosis was deep abdominal wall abscess given the clinical presentation and obvious pus discharge coming from the umbilicus. Other differential diagnosis could have been infected sebaceous cyst of the umbilicus but what went against it is the abscess was deep seated and there was no history of umbilical swelling suggesting sebaceous cyst. Another condition which could have led to umbilical discharge is pilonidal sinus of the umbilicus; however, there was no chronic history of discharge and there was no presence of any hairy bodies. Presence of foreign body and embryonal anomalies, such as patent urachus/vitelline duct were also differential diagnosis; however, they were ruled out by the CT scan.

Treatment

Patient was planned for surgery for incision and drainage and further exploration under general anaesthesia. An incision was made over the supraumbilical swelling and massive amount of foul smelling pus drained. During the exploration of the extra abdominal abscess cavity, there were two small abdominal wall defects (umbilical and supraumbilical) each around 1.5 cm in size with small bridge between them. Part of the appendix was protruding through the umbilical defect and an intact part of a small bowel and omentum were adherent to the other defect forming part of the abscess cavity (figure 4). The two defects were opened together. The appendix was found perforated. Small bowel and omentum were washed, released from the abscess cavity and appendectomy was performed from the hernia sac itself.

Figure 4.

Part of the appendix was protruded through the umbilical defect.

Abdominal wall defects were closed with Prolene. The abscess cavity was irrigated, packed and dressed daily with betadine pack.

Postoperation patient was kept on intravenous cefuroxime and metronidazole.

Outcome and follow-up

Hospital stay was uneventful and the patient was discharged on the fourth postoperative day on oral antibiotics, analgesia and daily dressing.

Patient was followed up weekly in the surgical clinic for wound care and the wound had completely healed by the fifth week.

Discussion

Sometimes abdominal wall swelling and abscess can be a manifestation of various intra-abdominal pathologies.^10–16 Appediceal perforation is one of these pathologies and its well described in the literature,^17–19 with some being reported being perforated within an inguinal hernia.²⁰

Appendiceal mucocele is a rare condition and it is classified into four histological types: (1) retention cysts, (2) mucosal hyperplasia, (3) mucinous cystadenoma and (4) mucinous cystadenocarcinoma.^{21 22} All of these changes lead to the formation of a mucocele, which can be defined as a dilation of the appendix resulting from excessive mucinous production. Mucinous cystadenoma is a rare cystic neoplasm of the vermiform appendix, characterised by villous adenomatous changes of the appendiceal epithelium that are associated with marked distension of the appendiceal lumen with mucin.²³

According to PSOGI,²⁴ the diagnostic terminology for primary appendiceal neoplasms is divided into two categories, non-invasive (low-grade appendiceal neoplasm, high-grade appendiceal mucinous neoplasm, serrated polyp with or without dysplasia and conventional adenoma resembling colorectal type) and invasive neoplasm (mucinous adenocarcinoma, signet ring cell carcinoma and non-mucinous adenocarcinoma).

LAMN is a mucinous neoplasm with low-grade cytology and any of the following: (1) loss of muscularis mucosae, (2) fibrosis of submucosa, (3) undulating or flattened epithelial growth, (4) ‘pushing invasion’ (expansile or diverticulum like growth), (5) dissection of acellular mucin in the wall and (6) mucin and/or neoplastic cells outside of the appendix. In our patient, the histological features is of LAMN.²⁴

The clinical presentation of patients with appendiceal mucinous cystadenoma may include right lower quadrant pain, change in bowel habits, per rectal bleeding or a palpable mass. Around 23%–50% of patients are asymptomatic and being discovered incidentally during surgery, radiological evaluations endoscopic procedure or during operations.^{25 26} Rarer manifestations include enterocutaneous fistula, Nawal et al reported a case of 65-year-old woman with 15 days history of pus discharge from inguinal wound, surgery revealed retroperitoneal appendix with mucoid material. Histopathology showed mucinous cystadenoma of the appendix with pseudomyxoma.²⁷ Other rare manifestations include deep venous thrombosis of the lower limb secondary to external iliac vein compression and intussusception.^{28 29} Cases of appendiceal mucinous cystadenoma presenting as an umbilical hernia has also been reported. Ren et al ³⁰ presented a case of a 66-year-old woman with 6 months history of umbilical mass diagnosed as umbilical hernia but on surgery they found appendix wrapped with mucous and calcification. Histopathology showed appendicular mucinous cystadenoma with malignant potential.³⁰ Our case is unique in term of clinical presentation and surgical findings. A thorough search of the literature revealed no similar cases published yet.

Ultrasound and CT are useful radiological imaging in the diagnosis and assessment of intra-abdomial and abdominal wall collections.^31–33 In cases with enterocutanous fistula or sinus formation, fistulogram and sinogram may be useful.³⁴

We would like to emphasise on radiological imaging in such cases. Several findings may be detected through radiological imaging. Abdominal X-ray may reveal arcuate calcifications at the location of the appendix which present in half of the cases.³⁵ Ultrasonography shows a distended appendix with a cystic, anechoic content or in some cases may contain a finely echogenic sediment in layers moving with position change.³⁶ Associated mucoid effusion may be seen and in women, an ovarian mass should be looked for (an associated mucinous tumour of the ovary). The most useful imaging examination is CT scan. It shows a formation of liquid density connected to the ceacum, with its walls sometimes finely calcified and enhanced by the contrast, and more or less regular depending on the aetiology.³⁶ CT scan also allows complications to be diagnosed: inflammation, torsion, invagination, ureteric compression and finally, the most to be feared, pseudomyxoma which is the peritoneal or retroperitoneal accumulation of gelatinous substance secondary to the rupture of a mucinous appendiceal lesion.^{36 37} The definitive diagnosis is through histopathological examination of the resected specimen.

The treatment of appendiceal mucoceles is surgical because of their malignant potential and the possibility of rupture in 5%–15% of the cases with the risk of dissemination and peritoneal pseudomyxoma.³⁸

Preoperative imaging is an important part of diagnosis in such cases where the actual symptoms are masked. The diagnosis for our patient was challenging due to her clinical presentation. Furthermore, our patient was obese and we were not able to reach a proper diagnosis through ultrasonography. Hence, an abdominopelvic CT was performed. Although sonography and CT sonogram can be far superior and faster to diagnose the same, we should not forget the the fact that the ultrasound is an operator-dependent procedure and CT sinogram may not be available in all centres as an emergency tool.

What we have learnt from this case, is that any patient presenting with abscess cavity around an abdominal hernial defect, the complications of its content should always be considered. In addition, possibility of herniated appendix should not be neglected. If, during an operation, herniated appendix is found, precaution should be taken during incision and drainage especially in elderly individuals due to the possibility of perforated mucinous cystadenoma which can lead to pseudomyxoma peritonei if the cells spill into the peritoneal cavity spontaneously or iatrogenically.

Always consider rare abdominal pathologies which can present with signs and symptoms mimicking more common diseases which make the diagnosis difficult and these rare pathologies should also be thought of during diagnosis. Also, benign looking tumours with or without malignant potential, should be included as a differential diagnosis.

Patient’s perspective.

I came to the hospital in the emergency department with a lot of smelly pus coming out from the abdomen. As soon as I reached, I was then examined by the surgical doctor who explained to me that even though my problem looked like a simple infection, it could be a deeper problem. The doctor assured me that I will not have to wait or suffer with the problem anymore. I was taken for CT scan and ultrasound after which the team of doctors told me that the problem did appear deeper as expected. They took my consent for the surgery and they explained to me that the plan was to remove all the pus and also examine my intestines for infection at the same time. After the operation, I had a smooth recovery and good after care. I felt relief from the stress I was facing all this while about not knowing the cause of the pus and was happy that the problem had now resolved. I was able to walk the next day and I had daily dressings for my wounds. I was then discharged from the hospital. I had weekly appointments with the doctor till my wounds healed and the doctor assured me that all was fine now. Now I feel a lot healthier and I am able to carry out my daily activities without any help or assistance. I immensely thank the entire surgical team for the timely action and for taking care of me and helping me lead a healthy and happy life.

Learning points.

• The importance of adequate preoperative imaging in patients presenting with deep abdominal wall abscess to exclude the involvement of intra-abdominal structures.

• In obese patient, ultrasound may not provide adequate diagnosis and CT would be more superior.

• Any patient presenting with abscess cavity around an abdominal hernial defect, the complications of its content should always be considered.

• Possibility of herniated appendix should not be neglected.

• Blind interventions for deep abdominal wall abscess should be avoided especially when there a suspicion.

• Possibility of rare appendicular pathologies/presentations should kept in mind in similar cases.

• Rare abdominal pathologies can present with signs and symptoms mimicking more common diseases which can make the diagnosis difficult. Hence, these rare pathologies should also be thought of during diagnosis.

• Benign looking tumours with or without malignant potential should always be included as a differential diagnosis when one encounters such cases.