Angiomyoma of the upper lip: report of a case with electron microscopic and immunohistochemical observation.

Immunohistochemical and electron microscopic observations of a vascular leiomyoma of the upper lip are presented. Tumour cells were positive for desmin, vimentin and neuron specific enolase but not for S-100 protein. Factor VIII was detected in the endothelium of blood vessels. Ultramicroscopically, the spindle-shaped tumour cells had elongated nuclei and cytoplasm containing abundant myofilaments and pinocytotic vesicles. Emphasis is placed on the fact that an immunohistochemical approach using appropriate antibodies can be used in identifying this tumour.