papillary mesothelioma (WDPM) is considered a specific clinico-pathologic entity distinct from
conventional diffuse malignant mesothelioma.
The majority of cases have been reported in the
peritoneum in women of reproductive age with no history of asbestos exposure
and also in the tunica vaginalis of men. Cases have also been reported in
WDPM is often
discovered incidentally during abdominal or pelvic surgery.
The tumour has an
indolent clinical course and with a good prognosis. Occasional cases are
more aggressive and require long term clinical follow-up.
Multiple grey white nodules usually less than 20mm in
Well defined stout
papillary structures with myxoid cores, lined
by bland, flattened, single layer of cuboidal or columnar mesothelial cells.
Subnuclear vacuolation may be noted.
Mitotic figures are rarely present. In
some cases there may be limited invasion
of the submesothelial layer.
Deep invasion is usually not
hyperplasia (assocciated with inflammation) ;
Serous neoplasia of
peritoneum (cellular stratification,atypia and mitotic figures);
Primary and seconday
adenocarcinoma (mucin histochemistry and immunohistochemistry are useful ) ;
with a prominent tubulopapillary epithelial component (diffuse growth
pattern and cytological atypia).