tumor of the follicular infundibulum ( tfi ) is a rare benign neoplasm providing two distinctive clinical patterns : the solitary and the eruptive form .
the clinical presentations resemble many other dermatologic conditions and require histopathological study to make a definite diagnosis .
although the tumor is called a tfi , it is not a neoplasm with infundibular differentiation .
we herein report the case of a tfi patient who presented with multiple asymptomatic hypopigmented macules resistant to the treatments .
a 50-year - old man presented with a clinical history of multiple asymptomatic lesions of the face , neck , upper chest and back spanning more than 20  years .
the size of the lesions ranged from approximately 3 to 20  mm in diameter ( fig . 
administration of 5% liquor carbonis detergens for many years resulted in only minimal improvement.fig . 
1hypopigmented angulated macules on face , neck ( a ) and upper chest ( b ) hypopigmented angulated macules on face , neck ( a ) and upper chest ( b ) a biopsy was performed and histopathologic examination revealed a plate - like fenestrated subepidermal tumor extending horizontally under the epidermis with multiple cord - like connections to the overlying epidermis .
this patient was treated with carbon dioxide laser ablation.fig .  2 
 a plate - like fenestrated subepidermal tumor extending horizontally under the epidermis with multiple cord - like connections to the overlying epidermis ( h&e 20 ) .
b peripheral palisading of the basaloid cells ( h&e 40 ) 
 a plate - like fenestrated subepidermal tumor extending horizontally under the epidermis with multiple cord - like connections to the overlying epidermis ( h&e 20 ) .
b peripheral palisading of the basaloid cells ( h&e 40 ) all procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation ( institutional and national ) and with the helsinki declaration of 1975 , as revised in 2000 and 2008 .
all procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation ( institutional and national ) and with the helsinki declaration of 1975 , as revised in 2000 and 2008 .
tumor of the follicular infundibulum is considered as a rare benign neoplasm , first described by mehregan and butler in 1961 .
however , the estimated frequency is 310 per 100,000 biopsies and the tumor develops predominantly in women .
usually , solitary tumor presents as scaly papule or nodule up to 1.5  cm in diameter and distributed on the head and neck or trunk of middle - aged and elderly patients [ 24 ] .
abbas and mahalingam reported 3 cases of multiple tfi ( 6% ) from 50 cases in 2009 and alomari et al . reported 13 cases ( 7.7% ) from total 168 cases in their study [ 3 , 4 ] .
the eruptive form has been described in most reports as symmetrically distributed tumors of variable scaling , hypopigmented macules and papules with irregular or angulated borders confined to the face , neck and upper trunk .
rarely , the tumors occur on the extremities and buttocks [ 5 , 6 ] .
the number of tumors varies from fewer than twenty to more than a hundred , and they are usually asymptomatic .
the differential diagnosis of tfi is one of the most challenging issues because the tumor also resembles many other dermatologic conditions .
differential diagnosis of hypopigmented macular lesions includes tinea versicolor , pityriasis alba , vitiligo , tuberculoid leprosy and idiopathic guttate hypomelanosis [ 3 , 5 ] .
for the depressed lesions , differential diagnosis includes acne scars , atrophic lichen planus , lichen sclerosus et atrophicus , disseminated superficial actinic porokeratosis and discoid lupus erythematosus [ 3 , 6 ] .
finally , differential diagnosis of papular lesions includes basal cell carcinoma , melanocytic nevi , seborrheic keratosis , actinic keratosis , prurigo nodularis , warts and trichoblastoma [ 3 , 6 , 7 ] . because of the variety of clinical presentations , the histopathological study is the most important method for providing a definite diagnosis .
histopathological findings in both forms of tfi consist of the plate - like growth of epithelial cells in the upper part of the dermis , expanding parallel to the epidermis , and showing peripheral nuclear palisading of the individual nest [ 2 , 5 , 8 ] .
some articles report an increase in elastic fibers surrounding the tumor [ 2 , 4 ] .
the histopathological difference between the solitary and eruptive form is the decrease of epidermal melanin , particularly in the tumor area , which can be correlated with the clinical form of hypopigmentation presented in the eruptive variant [ 2 , 3 ] .
histologically , tfi should be differentiated from basal cell carcinoma , superficial fibroepithelial tumor of pinkus , trichilemmoma , inverted follicular keratosis and pilar sheath acanthoma [ 4 , 5 ] .
most articles propose that the origin of the tumor is the follicular infundibulum , regarding the topography of the tumor proliferation and glycogen in the tumor cells [ 1 , 2 ] .
others hypothesize that the origin of the tumor is the isthmus part of the follicle , regarding tumor cells showing trichilemmal differentiation and the reports of sebaceous differentiation [ 9 , 10 ] .
the eruptive form has been reported in association with cowden s disease , nevus sebaceous , actinic keratosis , junctional melanocytic nevus , desmoplastic malignant melanoma , trichilemmoma , epidermal inclusion cysts and transformation to basal cell carcinoma .
however , the associations are not strong and should be considered only in additional cases which raise clinical concerns .
treatments reported for tfi include topical steroids , topical retinoic acid , topical keratolytics , topical imiquimod , etretinate , cryotherapy , curettage , excision and ablative laser , all with unpleasant results .
our patient was treated with carbon dioxide laser ablation and the short - term result was satisfactory .
although only a single reported case of transformation to basal cell carcinoma exists , the possibility of this outcome should be considered [ 11 , 12 ] .
long - term follow - up , especially in the case of eruptive form , should be performed since complete treatment is not practicable .
in conclusion , we report the case of tfi to remind physicians of the clinical presentation of this rare tumor . moreover , hypopigmented macules are one of the more common clinical presentations in dermatological practices .
tfi should be included in the differential diagnosis when a patient with hypopigmented lesions , particularly on the head and neck area , does not respond to the treatment based on the clinical diagnosis . 

all procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation ( institutional and national ) and with the helsinki declaration of 1975 , as revised in 2000 and 2008 .
this article is distributed under the terms of the creative commons attribution noncommercial license which permits any noncommercial use , distribution , and reproduction in any medium , provided the original author(s ) and the source are credited .
 backgroundtumor of the follicular infundibulum ( tfi ) is considered as a rare benign neoplasm providing two distinctive clinical patterns : the solitary and the eruptive form . 
 the clinical presentations resemble many other dermatologic conditions and require histopathological study to make a definite diagnosis.objectiveto inform physicians of a clinical presentation of tfi.case reportwe report on a 50-year - old man who presented with multiple asymptomatic hypopigmented macules resistant to the treatments . 
 the histopathological study was consistent with tumors of the follicular infundibulum.conclusionhypopigmented macules are one of the more common clinical presentations in dermatological practices . 
 it is important to include tfi in the differential diagnosis when a patient with hypopigmented lesions does not respond to the treatment based on the clinical diagnosis.electronic supplementary materialthe online version of this article ( doi:10.1007/s13555 - 015 - 0079 - 0 ) contains supplementary material , which is available to authorized users . 
Electronic supplementary material
Introduction
Case Report
Compliance with Ethics
Discussion
Conclusion
Electronic supplementary material
Conflict of interest
Compliance with ethics guidelines
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