A rare case of trichoadenoma over the vulva

Abstract

Trichoadenoma of Nikolowski is a rare, benign, well differentiated, slowly growing tumor of the hair follicle which was first described in 1958 by Nikolowski. It usually occurs as a solitary nodular lesion between 3 and 15 mm in diameter. It commonly occurs on the face or the buttocks. Herein we report a case of a slowly growing nodular plaque over the vulva of a 60-year-old female, histopathologically proven to be a trichoadenoma. The lesion was completely removed by ablative carbon dioxide laser (CO2).

INTRODUCTION

Trichoadenoma is a rare benign tumor, with multiple cystic structures closely resembling the infundibular structures of the hair follicle.[1]

It presents as a non-specific nodule over the face or buttocks, however, unusual sites such as the neck, upper arm, thigh shoulder, and shaft of the penis may also be affected.[2]

Histopathologically numerous horn cysts are present throughout the dermis surrounded by eosinophilic cells. Ours is a case of a 60-year-old female with a trichoadenoma over the left labia majora, which presented as a slow growing nodular plaque. Her tumor was excised using CO2 laser.

CASE REPORT

A 60-year-old married female patient presented to us with asymptomatic gradually increasing skin lesion on vulva since 2 years. There was no history of risk of exposure to sexually transmitted diseases. There was no history of discharge from the lesion. No history of white discharge per vaginum or burning micturition. She had not taken any treatment in the past for the same. No past history of tuberculosis.

Examination revealed a firm, nontender, nodular plaque of 3.5 cm × 2.5 cm along with a few shiny papules along the right labia majora [Figure 1a]. The left labia majora, labia mijora, clitoris, and perianal areas were not involved. Oral mucosa was normal. There was no regional lymphadenopathy. Differential diagnoses considered were fibrosis lymphangioma circumscriptum, giant trichoepithelioma, sarcoidosis, lupus vulgaris, and deep fungal infection.

Figure 1.

(a) Nodular plaque over the left labia majora. (b) Post-treatment with CO2 laser-day 1. (c) Post-treatment - 2 months, healing with post-inflammatory hyperpigmentation

Histopathology from the lesion showed numerous horn cysts present throughout the dermis surrounded by eosinophilic cells [Figure 2a]. Few of the cyst walls were lined by eosinophilic epidermal cells and contained keratin [Figure 2b]; thereby leading to a diagnosis of a less known adnexal tumor trichoadenoma.

Figure 2.

(a) ×10 view: Showing numerous horn cysts present throughout the dermis. (b) ×40 view: Showing cyst walls lined by eosinophilic epidermal cells, containing keratin

DISCUSSION

Trichoadenoma of Nikolowski is a rare, follicular tumor considered as a neoplastic process by some authors and benign malformation by some others.[3,4]

Clinically it presents as a solitary slow growing grayish nodule measuring up to 1.5 cm in diameter, seen over the face (57.5%) and buttocks (24.2%). Other uncommon sites of involvement are the neck, upper arm, thigh, shoulder and shaft of penis. It may also present as a chronic discharging nodule[5] or as an ulcerated growth.[2]

Rare case reports of trichoadenoma in association with intradermal melanocytic nevus,[6] sebaceous carcinoma, basal cell carcinoma, syringocystadenoma papilliferum have also been recorded.[2]

Verrucous variants of trichoadenoma have also been reported.

Though it is a tumor of adulthood, infants as old as 20 months have also been reported to present with this tumor.[7] There is no sexual predilection.

Histopathologically numerous round to oval infundibulocystic structures are observed in the dermis. Numerous horn cysts are present surrounded by eosinophilic cells. In some instances, a single layer of flattened granular cells is interpolated between the horn cysts and surrounding eosinophilic cells. Some islands consist of only eosinophilic epithelial cells without central keratinization.[8]

The histogenesis of trichoadenoma remains unclear. It is assumed to have an association with trichofolliculoma and trichoepithelioma. Moreover, the histological similarity of trichoadenoma with trichoepithelioma suggests the development of immature hair structures. However, because the cyst wall consists of epidermoid cells and keratinization may take place with the formation of keratohyalin, it has been suggested that the tumor differentiates largely toward the infundibular portion of the pilosebaceous unit.[7]

The keratin profile expression of this tumor supports the theory that it differentiates towards the follicular infundibulum and the follicular bulge region.[1,9]

Treatment of trichoadenoma is surgical excision. In our case, we used CO2 laser at 9.0 watts with 100 mm hand piece (1.0 mm spot size) in superpulse mode to ablate the growth under local anesthesia [Figure 1b]. Patient is on regular follow up since the last 3 months. The area has healed with postinflammatory hyperpigmentation [Figure 1c]. There has been no recurrence so far and the normal Vulvar anatomy has been maintained.

CONCLUSION

The trichoadenoma is a mystifying follicular tumor. Though it is known to occur on the face and buttocks, newer cases with unusual manifestations are being reported. To the best of our knowledge, a histopathologically proven large trichoadenoma over the vulva has not been reported. Hence, this case is being documented for its rarity.