Mucinous Cystadenoma of the Mesorectum
By Goodman, Martin D | |
Proquest LLC |
Mucinous cystadenoma is a rare cystic lesion that has been well described in the ovaries. Other extraovarian sites of uncertain etiology have also been reported. Very rarely these tumors are isolated to the mesentery. This is the first report to describe a mucinous cystadenoma of the mesorectum.We provide a case report and overview of the literature addressing the proposed origin of mesenteric mucinous cystadenoma and the clinical, histologic, and surgical factors associated with the diagnosis and management of this cystic lesion.
A 50-year-old G6P3 premenopausal woman presented to the surgical clinic after she was found to have an elevated carcinoembryonic antigen (CEA) level on laboratory screening for an insurance physical. Her medical history was significant for Type II diabetes mellitus, depression, hemorrhoids, irregular menses, three vaginal deliveries, and three miscarriages in the first trimester. Her surgical history included a laparoscopic cholecystectomy, tonsillectomy, and cesarean delivery. Review of systems was pertinent for chronic diarrhea and menorrhagia. Physical examination revealed an obese patient (body mass index 41 kg/m2) without appreciable lymphadenopathy. Her abdomen was obese with well-healed surgical incisions but otherwise unremarkable. Bimanual examination demonstrated a large, firm, nonmobile mass in the rectovaginal space, which pushed the uterus anteriorly preventing palpation of the adnexa.
Laboratory evaluation revealed normal renal and hepatic functioning. Complete blood count and basic chemistries were normal. Her CA-125 level was within normal limits (7.9 U/mL; reference range, 0 to 35 U/ mL); however, her carcinoembryonic antigen (CEA) was 13.4 ng/mL (reference range, 0 to 2.5 ng/mL).
Diagnostic workup included colonoscopy (seven benign polyps), Papanicolaou smear (normal), and mammogram (normal). Transvaginal ultrasound showed a large complex adnexal mass and a small right ovarian mass. Computed tomography of the abdomen and pelvis demonstrated a 10-cm complex solid cystic mass in the presacral region of the lower pelvis. The relationship of the mass to the rectal wall could not be fully delineated radiographically.
The patient was taken to the operating room for exploratory laparotomy. Gross inspection of the abdomen revealed no other pathology. The leftcolon was mobilized down to the peritoneal reflection and on anterior displacement of the rectum, an approximately 10-cm mass was encountered in the retrorectal space. It did not adhere to the presacral fascia but was noted to be intimately involved with the mesorectum. The mass did not appear to involve the rectal wall, coccyx, uterus, or ovaries. A low anterior resection with stapled colorectal anastomosis was performed. The patient had an uneventful recovery and was discharged to home on postoperative day 5.
Pathologic examination demonstrated a 10.5 . 9 . 8.5-cm smooth multiloculated, thick-walled cyst containing abundant mucin. The mass arose in the mesentery and was attached to-but not invading-the rectal wall. Microscopically there were tall mucin-containing cuboidal cells. The mucinous epithelial component demonstrated features ranging from borderline atypia to mucinous carcinoma in situ. There was one focus of superficial invasion to a depth of 1 mm. The tumor was therefore classified as a mucinous cystadenoma of borderline malignancy. Endodermal and mesodermal derivatives, including dermal adnexal structures, were absent. No ovarian tissue was identified in the specimen. Thirteen lymph nodes were evaluated from the perirectal softtissue and deemed negative for malignancy.
Mucinous cystadenoma is an epithelial tumor most often found in the ovaries.1 They also infrequently occur in extraovarian sites. Mucinous cystadenoma of the mesentery is exceedingly rare. This is the first reported case of mucinous cystadenoma arising in the mesorectum. Interestingly, mucinous cystadenomas occur almost exclusively in adult women.
The origin of mucinous cystadenoma is unknown, although the gender predisposition contributes to a theory suggesting mullerian etiology with lesions arising from ectopic or supernumerary ovarian tissue. There indeed may be a relationship between estrogen receptors within the cuboidal cells of the cyst and tumor promotion.2
A second theory of origination suggests that mucinous cystadenomas are derived from the mesothelial layer of teratomas.3 Histologically, this appears plausible; however, it is unlikely to be the sole pathway for mucinous cystadenoma development. The tumor in the case reported here lacked endodermal and mesodermal structures, thereby eliminating the possibility of teratoma transformation as a source for the lesion.
Another, likely more probable theory of origination is that invagination of the peritoneum produces a mesothelium-lined cyst. The cyst then undergoes neometaplastic change into mucinous epithelium, with or without features of malignancy.2, 3 This theory is supported by the presence of calretinin, a mesothelial marker, which was first described by Subramony et al. in cells from a retroperitoneal mucinous cystadenoma.2
Mucinous cystadenoma can be divided into three pathologic subtypes. The most common are benign cystic lesions, which harbor no malignant potential. Additionally, tumors of ''borderline malignancy'' have been described, which can metastasize.2 Mucinous cystadenocarcinoma is the third, and very rare, variant of this cystic lesion. It is thought to be the result of malignant degeneration of amucinous cystadenoma and carries the risk of recurrence and possible metastasis.2, 4
Mucinous cystadenomas, regardless of location, have a similar gross andmicroscopic appearance. The tumors are typically thin-walled with inner projections or trabeculations. Microscopically, the cystic lesions are lined by columnar mucin-secreting epithelial cells with pale cytoplasm and basal nuclei. Immunohistochemical staining may be positive for CA19-9 and CEA.2
Early diagnosis is important given the potential for malignancy. Clinical presentation of mucinous cystadenomas is largely related to their size and location. Cystic tumors of the mesentery may be asymptomatic, as was the case for our patient. Laboratory abnormalities associated with mucinous cystadenoma have not been described in the literature; however, our patient presented with an elevated CEA level in the setting of a normal colonoscopy.
Standard imaging techniques such as plain film, ultrasound, computed tomography, and magnetic resonance imaging aid in the diagnosis of a cystic mass but are unlikely to be confirmatory for mucinous cystadenoma. Additionally, radiographic findings associated with mucinous cystadenoma can be misleading. Despite its diagnostic limitations, however, imaging nonetheless serves a valuable role in surgical planning.
As a result of the rare nature of mucinous cystic lesions, the gold standard for management has yet to be established. Complete surgical resection of cystic masses in the mesentery is recommended to confirm the diagnosis and prevent recurrence. Gross examination of the specimen at the time of resection or intraoperative frozen sectioning does not allow for differentiation among mucinous cystadenoma, cystadenocarcinoma, or other cystic lesions, thereby strengthening the rational for complete resection and pathologic examination. Enucleation, marsupialization, or simple aspiration is not recommended, regardless of intraoperative pathologic or gross appearance, due to the risk of malignancy and recurrence.
Whether laparoscopic resection is an appropriate alternative to open surgery for patients with borderline malignancy lesions or cystadenocarcinoma is an unanswered but important question. The potential for intraoperative spillage-and possible development of pseudomyxoma peritonei-regardless of surgical approach, should not be overlooked.
Prognostic data for mucinous cystadenomas that arise in the mesentery have not been reported. In general, outcomes for treatment of mucinous cystadenomas in any location are dependent on the histologic subtype. Complete resection of a benignmucinous cystadenoma is often curative. Tumors of borderline malignancy may also be treated to cure with complete resection; however, they have the potential for metastases and recurrence.4 Not surprisingly, mucinous cystadenocarcinoma carries the worst prognosis for both recurrence and death from disease in addition to the potential for pseudomyxoma peritonei. The rarity of this pathology prevents specific prognostic estimations. Our patient, now 36 months after surgical resection, remains disease-free to date.
REFERENCES
1. Hart WR. Mucinous tumors of the ovary: a review. Int J Gynecol Pathol 2005;24:4-25.
2. Subramony C, Habibpour S, Hashimoto LA. Retroperitoneal mucinous cystadenoma: report of a case with reference to histogenesis. Arch Pathol Lab Med 2001;125:691-4.
3. Ulbright TM, Young RH. Primary mucinous tumors of the testis and paratestis: a report of nine cases. Am J Surg Pathol 2003; 27:1221-8.
4. Banerjee R, Gough J. Cystic mucinous tumours of the mesentery and retroperitoneum: report of three cases. Histopathology 1988;12:527-32.
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