Answer: Pyogenic granuloma

Histology: The specimen is polypoid. The overlying surface epithelium is ulcerated. The underlying mucosa demonstrates large dilated stag-horn vessels set in a cellular stroma. On closer inspection, the cellular stromal component is comprised of cords of cells that form small luminal spaces filled with red blood cells. The cells do not exhibit significant atypia, but there are numerous mitotic figures.

Discussion: Pyogenic granuloma is a benign acquired polypoid form of capillary hemangioma of the nasal cavity that is histologically characterized by a lobular arrangement of proliferating small blood vessels. The time-honored term pyogenic granuloma draws attention to common secondary changes including ulceration and inflammation, but the lesion is neither an infectious or granulomatous process. The alternative designation of “lobular capillary hemangioma” better reflects its true essence.

Pyogenic granuloma occurs in all age groups. In the head and neck, they typically arise within the oral cavity or nasal cavity. The clinical presentation is that of a non-painful, purple-red polypoid mass that is friable and bleeds easily. The fundamental microscopic makeup is that of a lobulated capillary hemangioma. Each lobule consists of a compact tightly coiled proliferation of capillaries around a central larger feeding vessel. In the presence of ulceration, the stroma becomes inflamed and edematous, particularly in the superficial aspect of the lesion, and mitotic activity becomes highly variable. When these secondary stromal changes are pronounced, the lobular pattern is lost and the distinction between a lobulated capillary hemangioma and an exuberant granulation tissue is obscured. In these instances, histologic examination of the deeper aspect of the lesion represents the best prospect for identifying a preserved lobular arrangement of the vessels. Distortion of the typical lobular pattern can also cause confusion with various benign and malignant neoplastic processes. Pyogenic granulomas with a predominant solid growth pattern and brisk mitotic activity can be mistaken for more aggressive vascular lesions such as angiosarcoma and Kaposi sarcoma. When the central feeding vessels are the predominant feature as in the present case, pyogenic granuloma may be confused with solitary fibrous tumor and hemangiopericytoma. When the endothelial cells in these solid areas take on a more epithelioid appearance, the lesion can mimic epithelioid hemangioma, carcinoma or melanoma. Unlike malignant vascular, epithelial and melanocytic tumors, pyogenic granuloma is exophytic and circumscribed without infiltration of surrounding structures.