Pseudomyxoma extraperitonei: a rare presentation of a rare tumour

Abstract

Pseudomyxoma extraperitonei is rare lesion resulting from the rupture of an appendiceal mucocele into the extraperitoneal tissues. We report a case of an 80-year-old woman with a medical history for a left hemicolectomy and a laparoscopic cholecystectomy 11 and 6 years, respectively, referred to our hospital for abdominal pain of increasing severity localised to the right hemiabdomen. The abdominal examination revealed a mobile mass a multidetector CT was performed; the patient was taken to surgery which was performed with no complications. Histopathological analysis of the tumour reported a pseudomyxoma associated to a moderately differentiated adenocarcinoma. The patient remains asymptomatic at a 1-year follow-up.

Background

A rare presentation of a rare tumour.

Case presentation

An 80-year-old female patient was referred to our hospital with a 3-year history of abdominal pain of increasing severity localised to the right hemiabdomen. Her medical history was relevant for a left hemicolectomy for colonic poliposis and a laparoscopic cholecystectomy for gallstone disease 11 and 6 years, respectively, prior to her admission.

Investigations

On physical examination, she did not appear to be in acute distress. The abdominal examination revealed a mobile mass located to the right of the midline that extended from just below the costal border to the right iliac crest that was painful to palpation. There were no cervical, axillary or inguinal lymphadenopathies and there was not ascites. The rest of her exam was irrelevant. A multidetector CT (MDCT) was performed that showed a well-circumscribed mass anterior the right rectus muscle that measured 251×92 mm. The appendix and ovaries were not visible (figures 1 and 2).

Figure 1.

A multidetector CT showing an extraperitoneal mass.

Figure 2.

A multidetector CT showing an extraperitoneal mass.

Treatment

The patient was taken to operation where an extraperitoneal encapsulated mass was found without any involvement of neighbouring structures or intra-abdominal organs. It was completely resected without breaking the capsule or entering the abdominal cavity. Histopathological analysis reported a pseudomyxoma associated to a moderately differentiated adenocarcinoma. Immunohistochemistry was positive for CK20 and CDX2 and negative for CK7 and calretinin (intestinal origin) (figure 3).

Figure 3.

(A) Neoplastic epithelium with complex architecture, also appreciate abundant mucin (H&E, ×5). (B) Note cytological atypia and loss in nuclear polarity (haematoxylin and eosin, ×40). (C) CK20 and (D) CDX2 positive in neoplastic epithelium.

Outcome and follow-up

The patient was discharged 2 days after the surgery without any complications and continues to do well after 1-year follow-up.

Discussion

Pseudomyxoma peritonei was first described by Werth¹ in 1884 as a rare condition consisting of mucinous ascites. In 1948, Bonann² reported a pseudomyxoma involving only the retroperitoneum and it was first described by Coppii in 1950.³ Twenty years later, Early⁴ described a retroperitoneal mucocele of the appendix which contained 10 litres of mucus that had not ruptured and a complete curative excision was possible; this was termed by Moran⁵ as pseudomyxoma extraperitonei (PE) in 1988. Shelton et al⁶ later named it pseudomyxoma retroperitonei. Pseudomyxoma extraperitonei is a rare condition resulting from the rupture of an appendiceal mucocele into the extraperitoneal tissues. It can also arise from implantation of mucosal cells of the primary site accompanied of modified glandular cells with the ability to behave in an invasive tumour-like manner. Tumours of the appendix are very rare, with mucinous adenocarcinomas constituting 8% of all malignant neoplasms of the appendix with an estimated incidence of 0.2/100 000 population/year.⁷ Mucinous implants in the peritoneal cavity are almost always of appendiceal or ovarian origin.⁴ In a recent report, van Ruth et al⁸ suggest that the appendix is the primary source of most pseudomyxoma peritonei, which may then spread to sites like the ovaries. Unusual sources of mucinous adenocarcinoma causing pseudomyxoma peritonei have included colon, uterus, common bile duct, pancreas and the stomach. There are over 44 cases of PE or retroperitonei reported in the literature, most commonly presented as an extraperitoneal abdominal mass (table 1).

Table 1.

Pseudomyxoma extraperitonei reported cases

Age	Sex	Presentation	Primary tumour	Treatment	Outcome	Reference
74	M	Abdominal pain and mass	Appendiceal mucinous adenocarcinoma	Debulking right hemicolectomy chemotherapy	Recurrence 6 months, fistula year	Ioannidis14
68	F	Lumbar pain and mass	Appendiceal mucinous adenocarcinoma	Debulking right hemicolectomy chemotherapy	Disease free at 3 years.	Ioannidis14
48	F	Abdominal pain and mass	Ovary	Debulking right oophorectomy and chemotherapy	Recurrence at 4 years	Chamisa15
51	F	Right flank purulent and mucinous discharge, palpable mass.	Appendiceal mucinous adenocarcinoma	En block resection with a portion of iliac bone appendectomy, systemic chemotherapy and radiotherapy	NA	Cakmak16
80	F	Lower abdominal mass	Appendiceal mucinous adenocarcinoma	Resection of mucous and ileum, cecum both ovaries and uterus	NA	Niwa17
57	M	Lower abdominal pain and mass	NA	Excision of cyst radiotherapy chemotherapy	Alive and disease free at years	Solkar18
55	F	Right lower abdominal pain and mass, retroperitoneal abscess	Ascending solon cancer	Right hemicolectomy oophorectomy, mucous removal. Systematic chemotherapy	Alive, no recurrence 5 months	Hirokawa19
78	F	Right abdominal tumour and pain	Appendiceal cystadenocarcinoma	Right hemicolectomy	NA	Kojima20
NA	M	NA	Mucinous paraenteric cyst	NA	NA	Angelescu21
68	F	NA	Appendiceal mucinous adenocarcinoma	Appendectomy debulking of mucous, intraoperative chemotherapy, systemic chemotherapy	Recurrence at 5 month, disease free at 3 and a half years	Liu22
58	F	Abdominal pain, retroperitoneal mass	Mucinous cystadenoma (primary or secondary)	NA	NA	Matsuoka23
46	M	Skin fistula, abdominal pain and mass	Appendiceal mucinous adenocarcinoma	Right hemicolectomy	Recurrence at 3 months	Koizumi24
53	F	Retroperitoneal abscess	Appendiceal mucinous adenocarcinoma	Right hemicolectomy and debulking systemic chemotherapy	Alive at 1 year	Edrees25
NA	NA	NA	NA	NA	NA	Fujimura26
69	M	Abdominal mass and pain, weight loss	Appendiceal mucinous adenoma	Debulking	NA	Tsai27
NA	NA	NA	NA	NA	NA	Hemet28
NA	NA	NA	NA	NA	NA	Oyama29
56	M	Appendiceal abscess	Appendiceal mucinous adenocarcinoma	Drainage, radiotherapy	Recurrence, Death 39 months	Stevens30
65	M	Abdominal mass	Appendiceal cystadenocarcinoma	Debulking and appendectomy	NA	Mor31
39	NA	Right back pain and right lower abdominal mass	Appendiceal mucinous adenocarcinoma	Right hemicolectomy, resection of right iliopsoas muscle, partial peritonectomy	NA	Tamai32
NA	NA	NA	NA	NA	NA	Nobusawa33
NA	NA	Polyuria and back pain	Appendiceal mucinous cystadenoma	NA	NA	Baba34
81	M	Abdominal mass	Appendiceal mucinous cystadenoma	Debulking and appendectomy	Persistent discharge	Shelton6
47	M	Retroperitoneal mass with anterior thigh extension	NA	Excision	Disease free at 3 years	Fann et al35
NA	NA	NA	NA	NA	NA	Koyama36
NA	NA	NA	Appendix	NA	NA	Vladimirtseva37
58	M	Right loin pain and abdominal mass	NA	Drainage, appendectomy and repeat drainage. Chemotherapy, radiotherapy mucolytic agents, radiofrequency hyperthermia	Recurrence at 3 weeks, recurrence at 5 years with sinus formation. Alive at 10 years	Moran5
67	M	Flank pain and mass	Appendix	Surgical debulking retroperitoneal chemotherapy	Recurrence at 2 years. Recurrence at 5 years	Brady38
NA	NA	NA	NA	NA	NA	Shimabukuro39
NA	NA	NA	NA	NA	NA	Torgunakov40
NA	NA	NA	NA	NA	NA	Kayser41
NA	NA	NA	Appendix	NA	NA	Chetchueva42
NA	NA	NA	Appendiceal cyst	NA	NA	Chekharina43
NA	NA	NA	Probable appendicular	NA	NA	Coppini3
37	M	Tender abdominal mass	Mucocele of appendix	Evacuation of cyst in 2 stage procedure	NA	Bonnan2
57	M	Abdominal mass	Mucocele of appendix	Debulking of tumour	Alive at 2 years	Early4
50	F	Total uterine prolapse	Appendix	Excision, omentectomy, total hysterectomy and oophorectomy	No evidence of disease 2 years	Snyder and Vandivort.44
63	M	Retroperitoneal mass	Appendix	Excision	No evidence of disease	Early et al4
41	M	Pleural mass	Appendix	Chemotherapy	Death of disease 2.5 years	Radosavljevic et al45
65	M	Inguino labial hernia	Appendix	Excision	Alive with disease 9 years	Ben-Hur et al46
33	M	Scrotal mass	Rectum	Debulking, omentectomy	No evidence of disease at 9 months	Baker et al47
38	M	Pleural mass	Appendix	Excision, chemotherapy	Alive with disease at 2.5 years	Peek and Beets48
53	M	Retroperitoneal mass with skin fistula	Appendix	NA	NA	Koizumi and Noiguchi49
75	M	Scrotal mass	Appendix	Chemotherapy	Dead of disease	Al-Bozom9

The pathogenesis for extraperitoneal pseydomyxoma peritonei in most cases is explained by one of the following reasons: (1) a communication through hernial sac; (2) increased intra-abdominal pressure (cases of uterovaginal prolapse) or (3) a leak through the peritoneum (retroperitoneal presentation associated with intraperitoneal pseudomyxoma). In the absence of peritoneal pseudomyxoma, a variant of the anatomy of the appendix (retroperitoneal location) may be the explanation; however, it is still speculative.⁹ In the present case, we could not demonstrate a communication with the abdominal cavity. The port sites used for the laparoscopic cholecystectomy did not appear to be the source of access to the preperitoneum. Preoperative diagnosis is very rare; symptoms like fatigue, decreased appetite and slowly progressing pain are common. Ultrasound and MDCT may contribute to the diagnosis, typical findings of pseudomyxoma peritonei are ascites, localised fluid collection throughout the abdomen and pelvis, omental thickening and deformity of the liver surface may be absent in PE.^{10 11} Several treatments have been used. Sugarbaker et al¹² advocate radical surgery together with preoperative intraperitoneal and systemic chemotherapy. The reported 5-year survival of patients with Pseudomyxoma peritonei varies from 11% to 75% (mean 50%).¹³ The role of adjuvant treatment in Pseudomyxoma extraperitonei and survival rates are not well known owing to the scarcity of reported cases. However, the disease is benign and the prognosis is likely to be better than Pseudomyxoma peritonei as the vital abdominal structures are not involved.⁵

Learning points.

• Preoperative diagnosis is very rare.

• The disease is benign and the prognosis is likely to be better than Pseudomyxoma peritonei as the vital abdominal structures are not involved.

• The rarity of pseudomyxoma extraperitonei makes outcomes difficult to predict.