Multiple trichofolliculomas mimicking multiple trichoepitheliomas.

Trichofolliculomas are benign hair follicle hamartomas which were initially considered as hair follicle tumors. Usually presenting as a solitary lesion associated with a tuft of vellus hairs, multiple trichofolliculomas are rare. Trichofolliculomas are characterized by a histopathological feature of dermal keratin cyst with cyst wall showing radiating hair follicles. We report this case for the rare presentation of multiple trichofolliculomas on the face which clinically mimicked multiple trichoepitheliomas.

What was known?

Trichofolliculoma is usually solitary and multiple is rare. The characteristic histopathology is of a dermal keratin cyst with secondary follicles.

Introduction

Trichofolliculoma although classified under hair follicle tumors, essentially are benign hamartomas of the hair follicle.[1] They are rare and usually present as solitary lesions on the face often with a tiny tuft of fine white hairs arising from the surface.[2] Majority of the case reports are of solitary type. We report a case of multiple trichofolliculomas that clinically resembled multiple trichoepitheliomas.

Case Report

A 21-year-old male presented with multiple asymptomatic skin colored raised lesions on the face of 13 years duration. The lesions had gradually increased in size and number. There was a history of similar lesions in mother and sister. Clinical examination revealed multiple non-tender skin colored papules on the forehead, cheeks, nose, naso-labial folds and chin [Figure 1]. A clinical diagnosis of trichoepithelioma was considered and a biopsy done.

Figure 1

Multiple trichofolliculomas on the face

Haematoxylin and eosin stained sections showed a dermal keratin cyst lined by squamous epithelium. Strands of secondary hair follicles were seen radiating from the wall of the cyst. The adjacent dermis showed pilosebaceous units and a partially ruptured hair follicle eliciting a giant cell response [Figures 2 and 3]. On the basis of the histopathological features, a final diagnosis of trichofolliculomas was made.

Figure 2

Dermal keratin cyst with secondary hair follicles (H and E, ×5)

Figure 3

Secondary hair follicle from keratin cyst wall (H and E, ×20)

Discussion

Trichofolliculoma first described by Miescher.[3] is a rare hair follicle tumor that manifests as a solitary skin colored papule or nodule often with a central pore.[2] The characteristic feature is the tuft of fine white hair that projects from the pore.[2] Solitary trichofolliculomas occur primarily over the face, scalp and neck. Multiple trichofolliculomas are rare and have been reported on the upper extremities,[4] scrotum and penis,[5] and a patient with only two trichofolliculomas on ears with generalized multiple trichogenic myxomas.[6]

Trichofolliculoma usually appears in middle age. Childhood onset is rare. A patient with congenital trichofolliculoma has been described.[3]

The presence of vellus hairs in a tuft like pattern arising from the lesion is considered to a distinctive feature of trichofolliculoma.[7] However, trichofolliculomas undergo evolution during the course and thus, manifests with varying clinical and histopathological morphologies.[24] The three stages of trichofolliculomas include early, full developed and late stages.[4]

Another useful aid to the diagnosis of trichofolliculoma is dermascopy showing peripheral radial dark brown projections resembling a crown and described as ‘firework pattern’. These projections represent the nests of cells radiating from the follicular epithelium.[8]

The characteristic histopathological features of trichofolliculoma include a squamous epithelium lined keratin containing dermal cyst with radiating hair follicles from the cyst wall. These secondary hair follicles are interconnected with each other by epithelial strands in all cases.[2] These histopathological features tend to differentiate trichofolliculomas from other hair follicular tumors. Cohesive and branching clusters of keratinized squamous cells mixed with sebaceous cells are seen in fine needle aspiration cytology of trichofolliculoma.[9]

Two variants of trichofolliculomas include sebaceous trichofolliculoma and folliculosebaceous cystic hamartoma that may represent an evolutionary stage.[27] Even though trichofolliculomas are considered to be benign, perineural invasion has been described in a patient as well as recurrence following excision.[10] Association of vulval trichoepitheliomas with vulvar intraepithelial neoplasia III has also been reported.[11]

Our patient presented with multiple skin colored papules resembling trichoepitheliomas and it was only the biopsy which confirmed the diagnosis of trichofolliculoma. In view of the long standing duration of the lesions, the classical picture of vellus hairs protruding from the nodule was not seen. Our case was very similar to the previously reported case of multiple trichofolliculomas with numerous 0.3 to 1.5 cm sized papules and nodules without any vellus hairs.[4]

Our initial diagnosis was multiple trichoepitheliomas in view of the childhood onset; positive family history and clustering of lesions in the nasolabial folds but the characteristic histological features such as horn cysts and basaloid epithelial islands in the dermis were absent.

We report this case for its rarity of occurrence, onset in childhood, presence of family history of similar lesions, the clinical resemblance to trichoepitheliomas and the absence of clinically demonstrable vellus hairs.

What is new?

Clinical resemblances to trichoepitheliomas. Childhood onset and family history of similar lesions.