Accelerated growth of orbital schwannomas during pregnancy does not correlate with sex hormone- or growth factor receptor status

Purpose: Until now, three cases of growth of an orbital schwannoma during pregnancy have been published. We aim to provide additional insight in the effect of pregnancy on orbital schwannomas.Methods: We present two additional cases of accelerated growth of orbital schwannomas during pregnancy and investigate receptor expression profiles for estrogen, progesterone, androgen, VEGF, EGF, FGF, PDGF-Rβ and ki-67 in the two pregnant cases and six non-pregnant cases.Results: Case 1: A 26-year-old woman developed unilateral exophthalmos during pregnancy, with normal visual acuity and ocular motility. During a subsequent pregnancy, again the exophthalmos progressed. MRI showed a mass suggestive of schwannoma. After delivery, resection of the lesion was performed through an anterior approach. Pathology confirmed schwannoma. The expression profile was positive for estrogen- and FGF receptors and ki-67, but negative for progesterone-, androgen- and other growth factor receptors. Case 2: A 24-year-old woman presented with diplopia and unilateral pain during pregnancy. She had normal visual acuity, but a mild exophthalmos and elevation deficit. MRI revealed an extraconal mass suggestive of schwannoma. After delivery, resection was performed through an anterior approach. Pathology confirmed the diagnosis. The expression profile was positive for ki-67, but negative for sex hormone- and growth factor receptors.In the six non-pregnant cases the expression profiles varied, with only one subject showing a strong expression of estrogen-, progesterone- and androgen receptors.Conclusions: Orbital schwannomas can experience growth during pregnancy. The underlying mechanism remains unclear as hormone- and growth factor expression profiles show no correlation to the pregnant state.