Perioral keratoacanthomas with extensive perineural invasion and intravenous growth.

Four patients had squamous tumors of the perioral skin with clinical and microscopic hallmarks of keratoacanthoma. In addition, the lesions exhibited extensive perineural invasion and intravenous growth. Two of the tumors recurred soon after excision and required additional surgery. In another case, two subsequent keratoacanthomas developed in adjacent skin. There were no further recurrences after follow-up periods of 7, 24, 42, and 44 months. Lesions in two patients were extremely painful. Perineural invasion was found in each of nine pathologic specimens. The number of involved nerves in single sections of each lesion ranged from two to 59 and exceeded 20 in four specimens from three patients. Intravenous growth by keratoacanthoma was seen in five specimens from three patients. Nine veins were affected in one instance and four in another. Several of the tumors had a dispersed and deeply infiltrative pattern of growth. Measuring vertically from the surface of the lesion, the deepest focus of perineural invasion observed in the four patients ranged from 4.2 to 17 mm. Keratoacanthomas with this unusual constellation of findings may have a predilection for the central portion of the face.