A Clinicopathologic Study on Hair Follicle Tumors

Background: Data on the clinicopathologic features of hair follicle tumors in Korea are limited. Objective: The purpose was to investigate the clinical and histopathologic characteristics of hair follicle tumors in Korea. Methods: Two hundred sixty four cases of hair follicle tumors seen from 1999 to 2001 in Korea were analyzed clinically and histopathologically. Results and Conclusion: 1. The most common hair follicle tumor in Korea was pilomatricoma(81.0%), followed by trichoepithelioma(6.4%), dilated pore of Winer(3.8%), and proliferating trichilemmal tumor(2.2%). 2. Hair follicle tumors usually occurred as a solitary skin-colored nodule. The most commonly involved site was the face, and the peak age of presentation was 10 to 19. 3. Pilomatricoma usually occurred as a solitary skin-colored nodule. The most commonly involved site was the arm, and more than 50% of tumors occurred before the age of 20. Histopathologically, the tumor was often surrounded by fibrous capsule and was composed of basophilic and shadow cells. It was usually located in the dermis and extended into the subcutis. Retraction spaces between tumor nests and stroma were frequently observed. 4. Trichoepithelioma usually occurred as multiple skin-colored papules on the face. Histopathologically, the tumor was usually located in the dermis with sometimes connected to the epidermis. It frequently showed peripheral palisading. 5. Dilated pore of Winer usually occurred as a solitary brownish to pigmented papule on the face in middle-aged persons. 6. Proliferating trichilemmal tumor occurred as a solitary or multiple tumors. Histopathologically, the tumor was usually surrounded by incomplete fibrous capsule. Tumor cells frequently showed clear cell formation, nuclear atypia, mitosis, peripheral palisading, trichilemmal keratinization, and individual keratinization.