Facial nerve hemangiomas: Vascular tumors or malformations?

Abstract

Objective To reclassify facial nerve hemangiomas in the context of presently accepted vascular lesion nomenclature by examining histology and immunohistochemical markers. Study Design Cohort analysis of patients diagnosed with a facial nerve hemangioma between 1990 and 2008. Setting Collaborative analysis at a specialty hospital and a major academic hospital. Subjects and Methods Seven subjects were identified on composite review of office charts, a pathology database spanning both institutions, and an encrypted patient registry. Clinical data were compiled, and hematoxylin-eosin–stained specimens were reviewed. For six patients, archived pathological tissue was available for immunohistochemical evaluation of markers specific for infantile hemangioma (glucose transporter protein isoform 1 [GLUT1] and Lewis Y antigen) and for lymphatic endothelial cells (podoplanin). Results All patients clinically presented with slowly progressive facial weakness at a mean age of 45 years without prior symptomatology. Hemotoxylin-eosin–stained histopathological slides showed irregularly shaped, dilated lesional vessels with flattened endothelial cells, scant smooth muscle, and no internal elastic lamina. Both podoplanin staining for lymphatic endothelial cells and GLUT1 and LewisY antigen staining for infantile hemangioma endothelial cells were negative in lesional vessels in all specimens for which immunohistochemical analysis was performed. Conclusion Lesions of the geniculate ganglion historically referred to as “hemangiomas” do not demonstrate clinical, histopathological, or immunohistochemical features consistent with a benign vascular tumor, but instead are consistent with venous malformation. We propose that these lesions be classified as “venous vascular malformations of the facial nerve.” This nomenclature should more accurately predict clinical behavior and guide therapeutic interventions.