Objective—To evaluate progesterone and estrogen
receptor expression in meningiomas of the CNS in
dogs and cats.
Animals—8 dogs (1 of which was treated with gestrinone)
and 5 cats with intracranial meningiomas and 2
dogs with spinal cord meningiomas; tissue samples
were also obtained from 1 clinically normal dog and 1
clinically normal cat.
Procedure—Meningioma tissue was obtained during
surgery or at necropsy; samples were processed for
histologic classification and immunohistochemical
evaluation of the proportion of tumor cells with progesterone
and estrogen receptors. Correlation among
receptor expression, tumor grade, and histologic subtypes
Results—Several histologic subtypes of intracranial
meningiomas were detected among tissue samples.
In the cats, all intracranial meningiomas were benign.
Progesterone receptor immunoreactivity was detected
in 14 of 15 meningiomas. Progesterone receptor
expression was identified in > 80% of cells in 8
intracranial meningiomas (4 dogs and 4 cats) and 2
spinal cord meningiomas. In samples of malignant
transitional and granular cell meningiomas in dogs,
progesterone receptors were detected in 32 and
4.8% of cells respectively. In 1 cat, 38% of tumor
cells had progesterone receptors. In a dog treated
with gestrinone, no progesterone receptors were
detected in the intracranial meningioma. Estrogen
receptors were only detected in the tumor of 1 dog.
Conclusions and Clinical Relevance—Results indicate
a high proportion of progesterone receptors in
cells of meningiomas of the CNS in dogs and cats.
Antiprogesterone treatment may have a role in the
treatment of unresectable or recurrent meningiomas
in dogs and cats. (Am J Vet Res 2003;64:1310–1318)