Introduction: Solitary fibrous tumor is a soft tissue tissue tumor of unkno
wn histogenesis. Based upon histologic similarities and CD-34 expression, i
t has been suggested that these neoplasms bear some relationship to mesothe
lioma, and may represent its extra-pleural equivalent.
Methods: In order to further investigate this possible relationship, we exa
mined a series of five dermal and five extra-cutaneous solitary fibrous tum
ors with antibodies directed against the mesothelial markers calretinin and
HBME-1.
Results: AU the lesions failed to stain with the antibodies tested. This su
ggests that despite some similar histologic and immunophenotypic features,
these lesions are not immunophenotypically identical. Mesotheliomas are CD-
34-(+), calretinin(+), HBME-1(+), while solitary fibrous tumors are CD-34(), calretinin(-), HBME-1(-).
Conclusions: The histogenesis of solitary fibrous tumor remains elusive. It
is unlikely that tumor location or tumor de-differentiation accounts for t
he dichotomous staining properties, as these neoplasms show a similarly ben
ign histologic appearance regardless of location.