Primary retroperitoneal mucinous cystadenoma

Dear Editor,

Primary retroperitoneal mucinous cystadenoma (RMC) is an extremely rare clinical entity. To our knowledge only 28 cases of primary RMC have been described in adults and one in a child¹ in the literature.

A 24 year-old woman, with no significant previous medical history, presented to our hospital complaining for a palpable mass in the left abdomen. Physical examination revealed an abdominal mass to the left abdomen, which extended from the left hypochondriac region to the left iliac region. The mass was elastic, badly outlined and there was no tenderness, pain or ascites. Computerized tomography (CT) and magnetic resonance (MRI) scans demonstrated a large unilocular mass in the left abdomen measuring 14*13*7cm. The above mass pressed to the right the adjacent organs and the intestinal helixes and put pressure on the left psoas muscle. The mass didn' adhere to the above-mentioned structures. The dimensions of the uterus were normal but the adnexa couldn't be lined out clearly in the CT scans. For this reason, the patient underwent MRI, where the ovaries were described as normal. Tumor markers, including CA 19-9, CA 125 and CEA were normal. No definitive preoperative diagnosis could be established.

At laparotomy, the cyst did not adhere to the adjacent structures and could be easily removed without spillage of its content. At the histological examination, the surgical specimen consisted of an intact cyst, measuring 14*13*7cm, which was filled with a clear transparent mucinous liquid. Several histological sections showed that a single layer of tall columnar mucinous homogenous cells lined the cyst wall. Their nuclei were located basally. Pathological examination detected that the cyst had been a primary benign RMC.

Primary benign RMC are very rare tumors, occurring almost exclusively in women. The majority of patients present complaining about an asymptomatic palpable abdominal mass, while other symptoms may be vague abdominal discomfort or pain, flatulence or fullness. CT and MRI, that often reveal the presence of a cystic mass in the peritoneum, are important but cannot define the diagnosis.

The diagnosis can be established only after the histologic exam of the surgical specimen. RMC are classified into three types: benign, borderline and malignant^2,3. Primary RMC share histological similarity to ovarian mucinous cystadenomas but can arise at any location in the retroperitoneum without attachment to the ovary ². Their histogenesis still remains elusive.

In conclusion, we present another case of a primary benign RMC, which is a very rare clinical entity. Primary RMC must be included in the differential diagnosis when confronted with a retroperitoneal mass. The final diagnosis can be made only postoperatively after complete surgical removal by histologic exam.