Introduction
Trichofolliculoma is rare follicullarly differentiated hamartoma, showing many vellus hair(s), having central infundibular cyst. It commonly occurs in the face, scalp and neck regions. It presents in adult age. Few cases presenting in childhood and infancy have been reported in literature (Ishii et al., 1992). Patients with trichofolliculoma come to the clinic for cosmetic reasons or obstructive symptoms (nasal vestibule, eyelids and external auditory canal) (Morton et al., 1997; Pradip et al., 2014; Shivakumar et al., 2015).

Case report
A 2-year-old male child was brought by his father with complains of nodule in right cheek. The nodule was noticed only on palpation for last one year. It was growing very slowly and barely noticeable by visual examination. On clinical examination a nodule was present in the right cheek which was 2x2 cm, firm to hard in consistency, had well defined margins, not flutuant, not tender, not warm to touch and non translucent (Figure 1). There was no palpable lymphadenopathy. Systemic examination was with in normal limits.

Fine needle aspiration cytology was inconclusive. Surgical excision of swelling under general anesthesia was done and rhomboid flap was used to fill the defect (Figure 2). The histopathological examination was consistent with trichofolliculoma (Figure 3). Patient was followed up for two years and showed no recurrence.

Discussion
Trichofolliculoma is a rare hamartoma, first described by Miescher in 1944 as an adnexal cell tumor (Miesher, 1994). It is usually asymptomatic, unless it causes obstruction of natural orifices  or disfigurement to the patient. It may be associated with focal acantholytic dyskeratosis (Bogle et al., 2004). Trichofolliculoma does not shows any gender or racial predilection. Adult age is most common presentation though childhood and infantile forms have been also reported in literature (Ishii et al., 1992). The distribution of trichofolliculoma is common on face, head and neck regions.

The etiology of trichofolliculoma is not well understood. Morphology of trichofolliculoma shows similarities of anagen, catagen and telogen phases of normal hair in its cycle along with hyperplasia of Merkel cell (Hartschuh and Schulz, 1992). Histopathology shows a centrally dilated follicle from which several immature secondary follicle are seen radiating. The immature secondary follicles comprised cords of basoloid cells, vellus hairs and few foci of sebaceous differentation. Immunohistochemically  trichofolliculoma is characterized by the proliferation of abnormal CK15 positive hair follicle stem cells, differentiated towards the outer root sheath and attempting to develop hair but losing proper differentiation (Misago et al., 2010). One postulation for development of trichofolliculoma is disturbance in normal cell to cell adherent junction. E-cadherin/β-catenin system of adhesion molecules plays a crucial role in this processes. E-cadherin / β- catenin are normally located at membrane of hair follicle but in trichofolliculoma and especially trichoepithelioma it is cytoplasmically located (Bezdekova et al., 2007).

Diagnosis is made only by histopathological examination,  though FNAC and radiological investigations can be done to rule out other differential diagnosis. Cytology shows several cohesive as well as arborising branched groups of squamous cells with keratinisation. In our case cytology was inconclusive as no cellular element was seen (Alexander et al., 2007).

Treatment is by surgical excision and anatomical closure. Recurrence is rare. Malignant transformation as trichofolliculocarcinoma was reported having perineural invasion (Ster and Stout, 1979).
Conclusion
Trichofolliculoma is rare hair cell hamartoma. Childhood occurrence is more rare though occurred. Diagnosis is only by histopathological examination and treatment is by complete surgical excision. Recurrence is rare after complete surgical excision.
 
Acknowledgment
Written informed consent was taken by patient's father for publication of the article. We are very thankful for Mr. Madhusudan Sharma, Lab Technician Pathology and The E.S.I. Corporation for kind help and encouragement. Authors acknowledge the immense help received from the scholars whose articles are cited and included in references of this manuscript. The authors are also grateful to authors/editors/publishers of all those articles, journals and books from where the literature for this article has been reviewed and discussed.

Source of funding: None
Conflict of Interest : Nil

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