A 67-year-old female visited a dental office for her annual check-up. Extraoral examination revealed a large lesion on the lower lip.
Joen Iannucci Haring, DDS, MS
The patient stated that the lesion had been present for approximately six weeks. The patient described the lesion as Onon-tenderO and commented that she was currently using an over-the-counter product in an attempt to dry it out. When questioned about her last medical visit, the patient stated that she was last seen by a physician several months earlier for a blood pressure evaluation.
The patient?s medical history included hypertension controlled by medication and a myocardial infarction. The patient?s dental history included regular examinations and routine dental treatment.
Intraoral examination revealed no significant positive findings. Extraoral examination of the head and neck region revealed one non-tender, well-demarcated nodule located on the outer edge of the vermilion border of the lower lip (see photo).
The lesion measured approximately 1 centimeter in diameter and exhibited a central crusted area. No enlarged or tender lymph nodes were detected upon palpation, and no other lesions were noted during the extraoral examination.
Based on the clinical information available, which one of the following is the most likely diagnosis?
o molluscum contagiosum
o sebaceous hyperplasia
o squamous cell carcinoma
o basal cell carcinoma
The keratoacanthoma is an epithelial proliferation that resembles squamous cell carcinoma and is believed to be caused by the human papillomavirus. This lesion is most often associated with sun-exposed skin.
Approximately 8 percent of all cases are found on the vermilion border of the lip. The upper and lower lips are involved with equal frequency. The keratoacanthoma is typically seen in elderly individuals and rarely occurs before the age of 45. Males are affected more frequently than females.
The keratoacanthoma typically presents as a well-defined nodule measuring 1 to 2 centimeters in diameter. The lesion is non-tender, dome-shaped, and firm with a central plug of keratin. The keratin plug appears yellow, brown, or black in color and may exhibit a crusted surface.
The keratoacanthoma is characterized by rapid growth and usually reaches 1 to 2 centimeters within six weeks. The keratoacanthoma occurs singly or in multiples. In patients who demonstrate large numbers of lesions, there appears to be a hereditary factor associated with the appearance of the multiple keratoacanthomas.
The diagnosis of a keratoacanthoma is determined based upon histologic examination. This lesion warrants an excisional biopsy with inclusion of adjacent normal tissue in order to definitively distinguish it from a well-differentiated squamous cell carcinoma.
The majority of keratoacanthomas regress spontaneously within six to 12 months of the onset. A depressed scar remains after the regression. Despite the propensity of this lesion to involute and disappear, surgical excision is recommended in order to provide an optimal esthetic appearance for the patient. Approximately 2 percent of patients experience recurrence following excision.
Joen Iannucci Haring, DDS, MS, is an associate professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.