Clinical History:
32-year-old male with 10 year history of crampy abdominal pain.
Radiographic Findings:
CT and US confirm a multiloculated cystic lesion centered over the bladder
and surrounding (but not obstructing) bowel, extending up toward the right
lower quadrant, and contiguous with the rectum.
Discussion:
Cystic peritoneal mesothelioma (CPM) is a primary tumor
of the peritoneal mesothelium. They can arise from any peritoneal surface,
but greater than 50% arise from the pelvic peritoneum, especially the
cul de sac, uterus, and rectum. Their incidence is much greater in females
than males (5:1) and the patient usually presents between the ages of
30-40 years.
Pathologically, one finds multiple mesothial-lined cysts within a delicate
fibrovascular stroma (Figures
4 and 5). Both pathologically and prognosticly it is, in some
ways, a cross between a malignant epithelial mesothelioma (the aggressive
tumor associated with asbestos exposure) and the benign adenomatoid tumor
of mesothelial origin (benign fibrous tumor of mesothilium). Some pathologists
prefer the designation of "multilocular peritioneal inclusion cysts."
There is support for an inflammatory pathogenesis; many of these patients
have had a history a prior abdominal operation or pelvic inflammatory
disease. These contiguous cysts grow along the peritoneum and mesentery
this is well-seen laproscopically (Figure
6) and at surgery (Figure
7).
The differential diagnosis is broad and includes: lymphangioma, enteric
cyst, seminal vesicle cyst, endometriosis, Tubo-ovarian abscess (TOA),
abscess, hematoma, ovarian neoplasm, cystic metastasis or stromal tumor,
and pseudomyxoma peritonei. Since this patient is a male, an ovarian neoplasm
can be discounted. However, ovarian neoplasms may mimic CPM, but in most
cases can be distinguished by their mural nodularity, associated mesenteric
and omental metastasis and accompanying ascites (this is true of cystic
metastasis as well). Psuedomysoma peritonei, on the other hand, is usually
more diffuse and seen in the upper abdomen as well; this characteristically
scallops the liver and spleen surfaces. Cystic stomal tumors are not multicystic
and demonstrate mass effect. Hematomas are also usually not multilocular,
have more complex fluid due to blood products (manifest as increased echogenicity
on US or increased density on CT) and are usually accompanied by a history
of trauma and/or anticoagulation. Abscesses of any origin are usually
distinguished by the clinical presentation of fever, pain, and leukocytosis.
Endometriosis is associated with despmoplasia and hemorrhagic contents,
clearly not seen in this case. A seminal vesicle cyst is associated with
an absent kidney and is unilocular. Enteric duplication cysts are characterized
by a thickened wall, often with a defined muscularis propria (seen on
US as a dominant mural hypoechoic band). Lymphangiomas may be indistinguishable
radiographically, but typically occur in children, more frequently in
boys, and are usually extrapelvic.
The prognosis for CPM is excellent. However, recurrence is common, occurring
in about one- half of the cases. Such recurrence may be seen months to
many years postoperatively. This is usually accompanied by the insidious
return of symptoms. Some argue that such recurrences are the result of
more postoperative adhesions while others purport the recurrence of this
benign neoplasm.
This is difficult case to prospectively obtain the diagnosis. It does
however, highlight the importance of developing and accessing a differential
diagnosis and the importance of clinical history.
Diagnosis:
Cystic peritoneal mesothelioma
References:
- O'Neil JD, Ros PR, Storm BJ, et. al. Cystic mesothelioma
of the peritoneum. Radiology 1989: 170: 333-337.
- Weiss SW, Tavassoli FA. Multicytic mesothelioma: an
analysis of pathologic findings and biologic behavior in 37 cases. Am
J Surg Pathol 1988:12:737-746
- McFadden DE, Clement PB. Peritoneal inclusion cysts
with mural mesothelial proliferation. Am J Surg Pathol 1986; 10:844-854.
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