Perianal thrombosis.

Two patients who had suffered numerous previous attacks of perianal hematoma were treated by excision of the lesions and adjacent skin (low hemorrhoidectomy). Histology confirmed that these lesions are not hematomas but thrombi lying within the thin-walled vessels of the external anal plexus. Excision of the perianal skin and underlying venous plexus, leaving anterior and posterior skin bridges, is indicated in patients who have multiple recurrences of this painful condition, which should be renamed "perianal thrombosis."