Frequency - International
Race
Sex
Age
Frequency - United States
The male-to-female ratio of trichilemmomas is 1:1; however, Cowden disease has a female predominance, with a male-to-female ratio of 1:3.
Trichilemmomas are relatively common benign neoplasms of the follicular epithelium. Their true incidence is hard to determine and is probably underestimated. Approximately 40 cases per 100,000 consecutive skin biopsies may be found every year in any given dermatopathologic laboratory. Unlike isolated trichilemmomas, multiple trichilemmomas associated with Cowden disease are very rare.
Trichilemmomas may occur in any race. They are most common in white females, but they have also been reported in Chinese, Japanese, and black patients.
Trichilemmomas predominantly occur in adult patients aged 20-80 years. However, onset may occur as early as age 4 years, with a median age of onset at 30 years.
The international frequency is unknown.
