Receptors in Acoustic Neuroma

To the Editor .—The recent interesting work of Klinken et al 1 demonstrates how results may vary depending on experimental methods. Specific estrogen and progesterone receptors have been demonstrated in acoustic neuroma tissue (19% positive for estrogen receptor, 17% positive for progesterone receptor, 8% positive for both), but typically in smaller concentrations than usually detected in breast tissue. 2 The difference between our results and those of Klinken et al most likely lies in the greater sensitivity of the methods we used, ie, radioimmunoassay performed on tissue cytosol by the dextran-coated charcoal method with Scatchard plot analysis. This method is also at least as specific as the immunocytochemical staining kit used by Klinken et al. Another reason for the nondemonstration of receptors by Klinken et al may be a lack of immunologic cross-reactivity of the test antigen between the receptors of breast and neuroma tissue. Resolution of this question must