Hybrid tumor combines elements of vascular leiomyoma, carvernous hemangioma

The authors describe a novel primary orbital vascular tumor that they call an angiomyfibroma that combines elements of both a vascular leiomyoma and a cavernous hemangioma.

The article includes a critical review of clinical records, diagnostic tests and radiographic studies of a 44-year-old male patient, combined with histopathologic evaluation with standard and special histochemical staining and immunohistochemical investigations.

The tumor presented with unilateral proptosis. The patient slowly developed 5 mm of well-tolerated relative right proptosis with minimal motility disturbance and no visual decline. Imaging revealed a medial, intraconal round mass that enhanced slowly with contrast and had a well-circumscribed anterior surface.

The tumor was resected minus the adherent posterior apical portion. Histology demonstrated a tumor composed of cavernous channels, capillary zone, compressed lumens with linear strands of endothelium, and collections of muscular veins devoid of elastic with a partial pseudocapsule. Immunohistochemical stain showed disorganized collections of smooth muscle cells in the intravascular spaces. Stains for CD31 and CD34 confirmed the presence of vascular endothelium.

The authors conclude that this hybrid tumor has low neoplastic potential and has features of a malformation. It is a composite variant of cavernous hemangioma associated with a conspicuous proliferation of anomalous disorganized smooth muscle cells (leiomyoma).

They write that most of the lesion lacked a pseudocapsule, which impeded surgical excision. Incomplete excision is recommended in such cases as this is preferable to the complications that could ensue from overly aggressive efforts at complete removal, particularly at the orbital apex, and since incompletely excised cavernous hemangiomas generally do not recur.