Immunohistochemical Identification and Image Analysis Quantification of Estrogen and Progesterone Receptors in Canine and Feline Meningioma

Oestrogen and progesterone receptor expression has been detected in human meningioma; in canine and feline meningiomas, however, the identification of steroid receptors requires further investigation. Fourteen meningiomas obtained from nine dogs and five cats were examined immunohistochemically for oestrogen receptors (ORs) and progesterone receptors (PRs). The immunolabelling reaction was quantified by light microscopy and image analysis. ORs were expressed in low numbers in two feline meningiomas and in one canine meningioma. PRs were more numerous, with more extensive tissue labelling. Conventional linear regression analysis showed that OR expression was not significant as compared with PR expression. PR expression was lowest in meningiomas with a high proliferation index, as determined by Ki67 expression. Conventional linear regression analysis between PR and Ki67 concentration confirmed a significant indirect relationship.