Case Report
Verrucous Trichoadenoma: A Case Report of a Rare Hair Follicle Tumor
Shatanik Bhattacharya*
Department of Dermatology, Venereology & Leprosy, Prafulla Chandra Sen Government Medical College, Arambag, India
*Corresponding author:Dr. Shatanik Bhattacharya, Department of Dermatology, Venereology & Leprosy, Prafulla Chandra Sen Government Medical College, Arambag, India E-mail Id: shatanik.bhattacharya.97@gmail.com
Copyright: © 2026 Bhattacharya S. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Article Information:Submission: 10/02/2026; Accepted: 12/03/2026; Published: 14/03/2026
Abstract
Introduction:Trichoadenoma is a rare hair follicle tumor with multiple cystic structures closely resembling infundibular structures of hair follicle. It presents as a non specific nodule over nose or buttock and varies from 0.3-5cm in diameter.It clinically mimics basal cell carcinoma.
Histopathologically, numerous horn cysts are present throughout the dermis surrounded by eosinophilic cells, in some instances,flattened layer of granular cells is interpolated between the horn cysts and several eosinophilic cells, some islands consists of only eosinophilic epithelial cells without central keratinization.This is a case of a solitary verrucous trichoadenoma of dorsum of nose.
Case Study:A 63 year old male presented with complaints of a swelling over dorsum of nose for 6 months,which initially started as a small blackish papule progressed to a growth of 2cmX1.5cm.No history of pain or discharge from the growth,no history of similar lesion elsewhere on the body. Examination revealed a firm,nontender plaque of size 2cmX 1.5cm over dorsum of nose,black in colour with ill-defined borders with a small raw red area at the distal end that appears to be punched out.All the laboratory investigations were within normal limits. Important differentials were Benign lichenoid keratosis, Trichoepithelioma, Trichofolliculoma,Trichoadenoma,Melanoma,Basal cell carcinoma,pilar sheath acanthoma,eccrine poroma.Wide local excision was done and sent for histopathological examination. Histopathological analysis revealed hyperkeratosis,acanthosis and papillomatosis of epidermis.Reticular dermis showed multiple discrete keratins filled cystically dilated hair follicles with few hair follicles in different stages of maturation. Dermo-epidermal junction shows band like inflammatory infiltrate,all resected margins showed presence of tumor.
Discussion:Trichoadenoma of Nikolowsky, rare follicular tumor considered as neoplastic process by some authors, benign malformation by others.It is a tumor of adulthood with no sexual predisposition. Clinically it presents as slow growing blackish nodule measuring upto 3cm in diameter,seen over face and buttocks. Neck,upper arm,thigh,shoulder are other uncommon sites, it can present as discharging nodule or an ulcerated lesion,the case presented as melanoma clinically turned out to be trichoadenoma on histopathology. The histogenesis of trichoadenoma remains unclear,,assumed to have association with trichoepithelioma and trichofolliculoma,histological similarity with trichoepithelioma proves its origin from immature hair follicle.All these tumors have strong predilection for central face.Association of trichoadenoma with intradermal melanocytic nevus,sebaceous carcinoma have been reported. The differentiation of trichoadenoma is thought to be of a maturity between that of trichoepithelioma (lessmature) and trichofolliculoma (more mature). It is highly distinctive because the degree of cystification is much more extensive than trichoepithelioma and basal cell carcinoma.Treatment of the trichoadenoma is surgical exci.
Histopathologically, numerous horn cysts are present throughout the dermis surrounded by eosinophilic cells, in some instances,flattened layer of granular cells is interpolated between the horn cysts and several eosinophilic cells, some islands consists of only eosinophilic epithelial cells without central keratinization.This is a case of a solitary verrucous trichoadenoma of dorsum of nose.
Case Study:A 63 year old male presented with complaints of a swelling over dorsum of nose for 6 months,which initially started as a small blackish papule progressed to a growth of 2cmX1.5cm.No history of pain or discharge from the growth,no history of similar lesion elsewhere on the body. Examination revealed a firm,nontender plaque of size 2cmX 1.5cm over dorsum of nose,black in colour with ill-defined borders with a small raw red area at the distal end that appears to be punched out.All the laboratory investigations were within normal limits. Important differentials were Benign lichenoid keratosis, Trichoepithelioma, Trichofolliculoma,Trichoadenoma,Melanoma,Basal cell carcinoma,pilar sheath acanthoma,eccrine poroma.Wide local excision was done and sent for histopathological examination. Histopathological analysis revealed hyperkeratosis,acanthosis and papillomatosis of epidermis.Reticular dermis showed multiple discrete keratins filled cystically dilated hair follicles with few hair follicles in different stages of maturation. Dermo-epidermal junction shows band like inflammatory infiltrate,all resected margins showed presence of tumor.
Discussion:Trichoadenoma of Nikolowsky, rare follicular tumor considered as neoplastic process by some authors, benign malformation by others.It is a tumor of adulthood with no sexual predisposition. Clinically it presents as slow growing blackish nodule measuring upto 3cm in diameter,seen over face and buttocks. Neck,upper arm,thigh,shoulder are other uncommon sites, it can present as discharging nodule or an ulcerated lesion,the case presented as melanoma clinically turned out to be trichoadenoma on histopathology. The histogenesis of trichoadenoma remains unclear,,assumed to have association with trichoepithelioma and trichofolliculoma,histological similarity with trichoepithelioma proves its origin from immature hair follicle.All these tumors have strong predilection for central face.Association of trichoadenoma with intradermal melanocytic nevus,sebaceous carcinoma have been reported. The differentiation of trichoadenoma is thought to be of a maturity between that of trichoepithelioma (lessmature) and trichofolliculoma (more mature). It is highly distinctive because the degree of cystification is much more extensive than trichoepithelioma and basal cell carcinoma.Treatment of the trichoadenoma is surgical exci.
Keywords:Verrucous Trichoadenoma; Keratin Cysts; Central Face; Benign Lichenoid Keratosis