Malignant proliferating trichilemmal tumour associated with human papillomavirus type 21 in epidermodysplasia verruciformis

Recent advances in cutaneous HPV infection

More than 200 types of human papillomavirus (HPV) have been reported to date and have been associated with various dermatological diseases. Among dermatological diseases, viral verrucae are the most commonly reported to be associated with HPV. Epidermodysplasia verruciformis (EV) consists of three types: typical EV is an autosomal recessive genetic disorder with TMC6/TMC8 gene mutations, atypical EV develops due to various gene mutations that cause immunodeficiency, and acquired EV develops due to acquired immunodeficiency. Generalized verrucosis differs from EV in that it involves numerous verrucous nodules (mainly on the limbs), histopathologically no blue cells as seen in EV, and infection with cutaneous α-HPVs as well as β-HPVs. HPV-induced skin malignancies include squamous cell carcinoma (SCC) caused by β-HPV (especially HPV types 5 and 8) in EV patients, organ transplant recipients, and healthy individuals, and SCC of the vulva and nail unit caused by mucosal high-risk HPV infection. Carcinogenesis of β-HPV is associated with sunlight. Mucosal high-risk HPV-associated carcinomas may also be sexually transmitted. We focused on Bowen's disease of the nail, which has been the subject of our research for a long time and has recently come to the fore in the field of dermatology.

A proliferating trichilemmal cyst in the perianal region: A case report

INTRODUCTION

Proliferating trichilemmal cysts (PTCs) are rare benign neoplasms originating from the follicular isthmus. They can undergo trichilemmal keratinization and malignant degeneration to form epidermoid carcinoma. They occur on the scalp in more than 90% of patients and are more common in elderly women.

PRESENTATION OF CASE

A 56-year-old woman complained of perianal discomfort upon sitting. She presented with a perianal nodule of approximately 3 cm in diameter that had exhibited slow and progressive growth over 8 years. After surgical excision of the lesion with safety margins, histopathological examination showed that it was a proliferating trichilemmal cyst in the perianal region.

DISCUSSION

There are no reports in the literature on PTC in the perianal region. The location with the highest prevalence is the scalp; other sites of occurrence are the neck, trunk, underarms, pubis, vulva, lower and upper limbs, upper lip, and gluteal region.

CONCLUSION

The development of PTC in the perianal region is an exceptional occurrence, and when it does occur, surgical treatment should always be indicated because of the risk of malignant degeneration to form epidermoid carcinoma.