Mucinous cystadenoma of the mesentery in ectopic ovarian tissue

Clinical History

A 37-year-old woman was referred for vague chronic abdominal pain. Her past history included three caesarean sections and a surgery for appendicitis complicated with peritonitis. Physical examination revealed a palpable soft mass, extending from the pelvis to the umbilical line. Laboratory findings and tumour markers were within normal range.

Imaging Findings

MRI revealed the presence of a large, well-circumscribed cystic mass, measuring 14x15x10 cm (Fig. 1). The lesion was mesenteric in origin, extending from pelvic brims to the lower pole of kidneys. Both ovaries were uninvolved and separate from the mass (Fig. 1b, c). The lesion was mainly slightly hyperintense and markedly hyperintense on T1 and T2-weighted images, respectively, findings suggestive for the presence of mucin. A few thin internal septa were seen. After gadolinium administration there was only wall enhancement detected, smooth, with a thickness of more than 3 mm (Fig. 1d). No areas of restricted diffusion within the mass were revealed (Fig. 1e). Imaging findings were strongly suggestive for the presence of a benign cystic mesenteric neoplasm, with mucinous content. Histology following cystectomy reported mucinous cystadenoma in ectopic ovarian tissue (Fig. 2).

Discussion

BACKGROUND
Ectopic ovarian tissue is a rare entity described first by Wharton in 1959 for all abnormally placed ovarian tissue [1]. He defined an accessory ovary as excess ovarian tissue adjacent and connected to a eutopic ovary and its blood supply. It is often found attached to the fallopian tube or one of the ligamentous structures of the ovarian-uterine complex. He reserved the term supernumerary ovary for ovarian tissue situated away from normal eutopic ovaries, with a separate blood supply [1]. Ectopic ovary can be found anywhere along the embryological migratory pathway of the ovarian primordium, including the mesentery, retroperitoneal space and omentum [1-6]. Lachman and Berman found that almost half of the reported cases since Wharton’s original description were in patients with previous pelvic surgery and pelvic inflammatory disease [2, 6]. These authors proposed a new classification of abnormally located ovarian tissue using the term ovarian implant/remnant, which was sub-classified as post-surgical or post-inflammatory implant and the true ectopic ovarian tissue as the consequence of alteration of embryogenesis and/or defective migration of ovarian primordium [2, 3, 6].
Ectopic ovarian tissue is often associated with tumours or cysts, mainly because these patients become symptomatic. The most common masses identified are mature cystic teratomas and mucinous cystadenomas (MC), present in 20% of patients [5-6]. Brenner’s tumour, sclerosing stromal tumour, serous cystadenoma, serous cystadenofibroma, fibroma and adenocarcinoma have also been described.
In this case the histologic diagnosis was of a mucinous cystadenoma arising in ectopic ovarian tissue located in the mesentery. MCs are benign cystic tumours arising mainly from the ovaries and the pancreas [7-10]. They have been rarely described in the kidneys, lung, hepatobiliary system, spleen, breast, appendix, retroperitoneum and paratesticular space. MCs arising from the mesentery are an extremely rare entity. Only 19 cases of mucinous mesenteric cystadenomas have been reported in the literature, with approximately 88% of these tumours discovered in women [7, 8]. Based on the female preponderance and the similarities in morphological and immunohistochemical profiles of ovarian MC and mesenteric mucinous tumours, the first theory of the pathogenesis included an origin from ectopic ovarian tissue, as it was in our patient [9]. However, the detection of this tumour in males has led to another theory of pathogenesis, including the invaginations of the peritoneum, which may result in inclusion cysts that undergo mucinous metaplasia, followed by cyst formation and subsequent MC development [7-10].

Differential Diagnosis List

Final Diagnosis

Mucinous cystadenoma of the mesentery arising in ectopic ovarian tissue

URL:	https://www.eurorad.org/case/11082
DOI:	10.1594/EURORAD/CASE.11082
ISSN:	1563-4086