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An ultrastructural and
immunohistochemical study of 10 cases
Mesotheliomas with rhabdoid morphology are rare and only two
individual case reports have been documented in the literature. This author
reports a series of 10 cases of mesotheliomas with rhabdoid features, nine
of which originated in the pleura and one in the peritoneum. Eight of the
patients were men and two were women. Six patients had a history of asbestos
exposure. Histologically, seven of the mesotheliomas were epithelioid, two
sarcomatoid, and one biphasic. The proportion of the rhabdoid cells seen in
these cases constituted 15-75% of the individual tumors. Cytoplasmic
staining in the rhabdoid cells was seen for pan-keratin and vimentin in all
10 cases, for keratin 7 in eight of eight, for calretinin in nine of 10, and
for keratin 5/6 in seven of nine. Nuclear positivity for WT1 was observed in
the rhabdoid cells of four of seven cases and membranous reactivity for
mesothelin in four of six, and for podoplanin in two of six. Only one case
showed desmin positivity in sparse cells in the nonrhabdoid component of the
tumor. All of the cases were negative for CEA, MOC-31, TAG-72, CD15, CD34,
bcl2, muscle-specific actin, and TTF-1. Ultrastructural studies revealed
paranuclear collections of intermediate filaments, but no evidence of
rhabdomyoblastic differentiation was seen. The mean survival of five of the
six patients for whom this information was available was 3.8 months. The
remaining patient had a survival time of 1 year. It is important for
pathologists to be aware that mesotheliomas can present rhabdoid features,
not only because they can be confused with other malignancies that can
exhibit a similar morphology, but also because of their apparently unusually
aggressive behavior.
Reference:
Mod Pathol. 2006 Jan 6 |