Tumor of follicular infundibulum–associated neoplasms

Abstract

Tumor of the follicular infundibulum (TFI) is a rare benign cutaneous adnexal neoplasm first described by Mehregan and Butler in 1961.1Mehregan A.H. Butler J.D. A tumor of follicular infundibulum. Report of a case.Arch Dermatol. 1961; 83: 924-927Crossref PubMed Scopus (57) Google Scholar TFI most commonly presents as a solitary papule, plaque, or macule, on the head and neck region.2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar Clinical variants include multiple or eruptive forms.3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar Histopathologically, solitary lesions present as platelike subepidermal proliferations of eosinophilic, pale-staining keratinocytes, creating a reticulated pattern.3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar, 4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar Many cases of TFI have been associated with other cutaneous lesions, stimulating discussions surrounding the histogeneis of TFI. Basal cell carcinoma (BCC) is the most commonly reported association, with varying rates of associated lesions seen in other reports.3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar Here, we present the case of a 69-year-old man with TFI and an associated dysplastic nevus. A 69-year-old man presented to the dermatology clinic for an annual skin check with a history of melanoma in situ and BCC on the right arm. On examination, there was a 4-mm atypical brown macule on the left upper back (Fig 1). The lesion was biopsied to rule out melanoma. On pathologic examination, hematoxylin-eosin–stained sections showed an atypical lentiginous junctional nevus (dysplastic nevus) (Fig 2, A). The atypical features included single melanocytic hyperplasia at the dermoepidermal junction, rete elongation and inter-rete bridging, lamellar fibroplasia, and a lymphocytic infiltrate. The melanocytes showed moderate cytologic atypia. Within the melanocytic proliferation, a platelike proliferation of anastomosing strands of pale staining cells was noted to arise from the epidermis, consistent with a TFI (Fig 2, B). The lesion was diagnosed as a dysplastic nevus associated with a tumor of the follicular infundibulum.Fig 2Biopsy of a lesion. A, A dysplastic nevus with single melanocytic hyperplasia at the dermoepidermal junction is seen with an associated tumor of the follicular infundibulum. B, Platelike proliferation of anastomosing strands of pale staining cells consistent with a tumor of the follicular infundibulum. (A and B, Hematoxylin-eosin stain; original magnifications: A, ×4; B, ×20.)View Large Image Figure ViewerDownload Hi-res image Download (PPT) TFI is a rare benign neoplasm that usually presents as a solitary lesion on the head and neck region.5Haddad N. Oliveira Filho J de Reis M.J.L. Michalany A.O. Nasser K. da R. Corbett A.M.F. Tumor of follicular infundibulum with unique features.An Bras Dermatol. 2014; 89: 964-966Crossref PubMed Scopus (7) Google Scholar Less common clinical variants have been described, including multiple and eruptive forms, which are typically referred to as infundibulomas.6Kossard S. Finley A.G. Poyzer K. Kocsard E. Eruptive infundibulomas. A distinctive presentation of the tumor of follicular infundibulum.J Am Acad Dermatol. 1989; 21: 361-366Abstract Full Text PDF PubMed Scopus (21) Google Scholar Infundibulomas are commonly found on the face, neck, and upper neck as well-demarcated hypopigmented lesions.5Haddad N. Oliveira Filho J de Reis M.J.L. Michalany A.O. Nasser K. da R. Corbett A.M.F. Tumor of follicular infundibulum with unique features.An Bras Dermatol. 2014; 89: 964-966Crossref PubMed Scopus (7) Google Scholar The solitary and multiple/eruptive variants of TFI present with similar histologic findings, namely, a proliferation of keratinocytes arranged in trabeculae and connected to the epidermis.7Kolenik 3rd, S.A. Bolognia J.L. Castiglione F.M.J. Longley B.J. Multiple tumors of the follicular infundibulum.Int J Dermatol. 1996; 35: 282-284Crossref PubMed Scopus (22) Google Scholar Although solitary variants tend to present in middle-age women, multiple and eruptive variants present in younger patients.5Haddad N. Oliveira Filho J de Reis M.J.L. Michalany A.O. Nasser K. da R. Corbett A.M.F. Tumor of follicular infundibulum with unique features.An Bras Dermatol. 2014; 89: 964-966Crossref PubMed Scopus (7) Google Scholar TFI is often associated with other cutaneous lesions. These associations have generated discussion regarding the histogeneis of TFI. Some believe TFI differentiates toward the infundibulum, given the topography of tumor proliferation and glycogen in the tumor cells.1Mehregan A.H. Butler J.D. A tumor of follicular infundibulum. Report of a case.Arch Dermatol. 1961; 83: 924-927Crossref PubMed Scopus (57) Google Scholar Others believe TFI differentiates toward the isthmus, given reports of sebaceus differentiation and trichilemmal differentiation.2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar With regard to their triggers, some argue TFI is a reactive process, whereas others believe TFI represents degeneration into BCC.2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar, 8Schnitzler L. Civatte J. Robin F. Demay C. [Multiple tumors of the follicular infundibulum with basocellular degeneration. Apropos of a case].Ann Dermatol Venereol. 1987; 114: 551-556PubMed Google Scholar Some have postulated that TFI shares a common folliculosebaceus origin with other neoplasms, thus explaining frequent associations with other cutaneous lesions.4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar Since the discovery of TFI in 1961, there have been many accounts of associated neoplasms (Table I).9Lee D.-W. Yang J.-H. Lee H.-M. et al.A case of tumor of the follicular infundibulum with sebaceous differentiation.Ann Dermatol. 2011; 23: 198-200Crossref PubMed Scopus (6) Google Scholar, 13MacGregor J.L. Campanelli C. Friedman P.C. Desciak E. Basal cell and squamous cell carcinoma occurring within a field of multiple tumors of the follicular infundibulum.Dermatol Surg. 2008; 34: 1567-1570PubMed Google Scholar, 14Hutchinson K.W. Boulton J.E. Sulivan T.J. Whitehead K.J. Clinicopathological report Periocular tumour of the follicular infundibulum.Clin Exp Ophthalmol. 2001; 29: 100-101Crossref PubMed Scopus (4) Google Scholar, 15Dore E. Noe M.H. Swick B.L. Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.J Cutan Pathol. 2015; 42: 645-651Crossref PubMed Scopus (9) Google Scholar, 16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar, 17Schirren C.G. Maciejewski W. [Tumor of the follicular infundibulum. Study of determining follicular differentiation].Pathologe. 1996; 17: 440-445Crossref PubMed Scopus (5) Google Scholar, 19Akasaka T. Kon S. A possible case of eccrine poroma arising in seborrheic keratosis with partial intermediate malignancy and tumor of the follicular infundibulum.J Dermatol. 1997; 24: 654-661Crossref PubMed Scopus (3) Google Scholar, 20Horn T.D. Vennos E.M. Bernstein B.D. Cooper P.H. Multiple tumors of follicular infundibulum with sweat duct differentiation.J Cutan Pathol. 1995; 22: 281-287Crossref PubMed Scopus (21) Google Scholar, 21Martin J.E. Hsu M.-Y. Wang L.C. An unusual clinical presentation of multiple tumors of the follicular infundibulum.J Am Acad Dermatol. 2009; 60: 885-886Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar One of the first mentions of TFI-associated lesions was in 1989, by Kossard et al.6Kossard S. Finley A.G. Poyzer K. Kocsard E. Eruptive infundibulomas. A distinctive presentation of the tumor of follicular infundibulum.J Am Acad Dermatol. 1989; 21: 361-366Abstract Full Text PDF PubMed Scopus (21) Google Scholar In studying eruptive infundibulomas, they found that the platelike epithelial architecture of TFI was seen in association with seborrheic keratoses and BCC.6Kossard S. Finley A.G. Poyzer K. Kocsard E. Eruptive infundibulomas. A distinctive presentation of the tumor of follicular infundibulum.J Am Acad Dermatol. 1989; 21: 361-366Abstract Full Text PDF PubMed Scopus (21) Google Scholar They did, however, note that these lesions lacked the dense elastic brushwork of the follicular infundibulum.6Kossard S. Finley A.G. Poyzer K. Kocsard E. Eruptive infundibulomas. A distinctive presentation of the tumor of follicular infundibulum.J Am Acad Dermatol. 1989; 21: 361-366Abstract Full Text PDF PubMed Scopus (21) Google Scholar In 1993, Ackerman et al22Ackerman A.B. Neoplasms With Follicular Differentiation. Lea & Febiger, Philadelphia, PA1993Google Scholar had not mentioned an association with BCC, but by 2001, they had observed this and attributed the association to chance.Table ISummary of TFI-associated neoplasms in the literatureAssociated neoplasmReportFrequencyBCCBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar34/64 (53.12%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar4/19 (21.05%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarLee et al9Lee D.-W. Yang J.-H. Lee H.-M. et al.A case of tumor of the follicular infundibulum with sebaceous differentiation.Ann Dermatol. 2011; 23: 198-200Crossref PubMed Scopus (6) Google Scholar1 (case report)Weyers et al10Weyers W. Horster S. Diaz-Cascajo C. Tumor of follicular infundibulum is Basal cell carcinoma.Am J Dermatopathol. 2009; 31: 634-641Crossref PubMed Scopus (16) Google Scholar5/24 (20.83%)9Lee D.-W. Yang J.-H. Lee H.-M. et al.A case of tumor of the follicular infundibulum with sebaceous differentiation.Ann Dermatol. 2011; 23: 198-200Crossref PubMed Scopus (6) Google ScholarAbbas and Mahalingam2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar7/53 (13.0%)2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google ScholarCribier and Grosshans11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar1 (case report)Inaloz et al12Inaloz H.S. Inaloz S.S. Unal B. Eralp A. Coexistence of tumor of the follicular infundibulum with an unusual trichilemmal tumor.Am J Dermatopathol. 2002; 24: 406-408Crossref PubMed Scopus (11) Google Scholar1 (case report)Macgregor et al13MacGregor J.L. Campanelli C. Friedman P.C. Desciak E. Basal cell and squamous cell carcinoma occurring within a field of multiple tumors of the follicular infundibulum.Dermatol Surg. 2008; 34: 1567-1570PubMed Google Scholar1 (case report)Schnitzler et al8Schnitzler L. Civatte J. Robin F. Demay C. [Multiple tumors of the follicular infundibulum with basocellular degeneration. Apropos of a case].Ann Dermatol Venereol. 1987; 114: 551-556PubMed Google Scholar1 (case report)Hutchinson et al14Hutchinson K.W. Boulton J.E. Sulivan T.J. Whitehead K.J. Clinicopathological report Periocular tumour of the follicular infundibulum.Clin Exp Ophthalmol. 2001; 29: 100-101Crossref PubMed Scopus (4) Google Scholar4 (case reports)Actinic keratosisBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar6/64 (9.38%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarAbbas and Mahalingam2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar2/53 (3.77%)2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google ScholarDesmoplastic malignant melanomaAbbas and Mahalingam2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar1/53 (1.89%)2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google ScholarJunctional melanocytic nevusAbbas and Mahalingam2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar1/53 (1.89%)2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google ScholarDesmoplastic trichilemmomaDore et al15Dore E. Noe M.H. Swick B.L. Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.J Cutan Pathol. 2015; 42: 645-651Crossref PubMed Scopus (9) Google Scholar1 (case report)Inaloz et al12Inaloz H.S. Inaloz S.S. Unal B. Eralp A. Coexistence of tumor of the follicular infundibulum with an unusual trichilemmal tumor.Am J Dermatopathol. 2002; 24: 406-408Crossref PubMed Scopus (11) Google Scholar1 (case report)Manonukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report)TrichoblastomaDore et al15Dore E. Noe M.H. Swick B.L. Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.J Cutan Pathol. 2015; 42: 645-651Crossref PubMed Scopus (9) Google Scholar1 (case report)Manonukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report)Epidermal Inclusion CystBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar2/64 (3.13%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar1/19 (5.26%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarAbbas and Mahalingaet al2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar1/53 (1.89%)2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google ScholarCribier and Grosshans11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar1 (case report)Nevus sebaceusDore et al15Dore E. Noe M.H. Swick B.L. Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.J Cutan Pathol. 2015; 42: 645-651Crossref PubMed Scopus (9) Google Scholar1 (case report)Alomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar1/19 (5.26%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarCribier and Grosshans11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar2 (case reports)Schirren and Maciejewski17Schirren C.G. Maciejewski W. [Tumor of the follicular infundibulum. Study of determining follicular differentiation].Pathologe. 1996; 17: 440-445Crossref PubMed Scopus (5) Google Scholar2 (case reports)Manonukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report)Melanoma in situAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar10.53% (2/19)4Tinea versicolorAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar1/19 (5.26%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarSquamous cell carcinomaBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar2/64 (3.13%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar3/19 (15.79%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarMacgregor et al13MacGregor J.L. Campanelli C. Friedman P.C. Desciak E. Basal cell and squamous cell carcinoma occurring within a field of multiple tumors of the follicular infundibulum.Dermatol Surg. 2008; 34: 1567-1570PubMed Google Scholar1 (case report)Lentigo malignaBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar2/64 (3.13%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar3/19 (15.79%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarIntradermal nevusBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar2/64 (3.13%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarSyringomaBaquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar1/64 (3.13%)3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google ScholarSyringocystadenoma papilliferumDore et al15Dore E. Noe M.H. Swick B.L. Trichoblastoma, syringocystadenoma papilliferum, desmoplastic trichilemmoma and tumor of the follicular infundibulum with signet-ring cells, all arising in nevus sebaceus.J Cutan Pathol. 2015; 42: 645-651Crossref PubMed Scopus (9) Google Scholar1 (case report)Mononukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report)Atypical junctional nevusAlomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar3/19 (15.79%)4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google ScholarDempsey et al (current study)1 (case report)Superficial epithelioma with sebaceus differentiationLee et al9Lee D.-W. Yang J.-H. Lee H.-M. et al.A case of tumor of the follicular infundibulum with sebaceous differentiation.Ann Dermatol. 2011; 23: 198-200Crossref PubMed Scopus (6) Google Scholar1 (case report)Mahalingam et al18Mahalingam M. Bhawan J. Finn R. Stefanato C.M. Tumor of the follicular infundibulum with sebaceous differentiation.J Cutan Pathol. 2001; 28: 314-317Crossref PubMed Scopus (26) Google Scholar1 (case report)Mucoepidermoid carcinomaManonukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report)Akasaka and Kon19Akasaka T. Kon S. A possible case of eccrine poroma arising in seborrheic keratosis with partial intermediate malignancy and tumor of the follicular infundibulum.J Dermatol. 1997; 24: 654-661Crossref PubMed Scopus (3) Google Scholar1 (case report)Horn et al20Horn T.D. Vennos E.M. Bernstein B.D. Cooper P.H. Multiple tumors of follicular infundibulum with sweat duct differentiation.J Cutan Pathol. 1995; 22: 281-287Crossref PubMed Scopus (21) Google Scholar1 (case report)HydrocystomaMartin et al21Martin J.E. Hsu M.-Y. Wang L.C. An unusual clinical presentation of multiple tumors of the follicular infundibulum.J Am Acad Dermatol. 2009; 60: 885-886Abstract Full Text Full Text PDF PubMed Scopus (9) Google Scholar1 (case report)Adenosquamous carcinomaManonukul et al16Manonukul J. Omeapinyan P. Vongjirad A. Mucoepidermoid (adenosquamous) carcinoma, trichoblastoma, trichilemmoma, sebaceous adenoma, tumor of follicular infundibulum and syringocystadenoma papilliferum arising within 2 persistent lesions of nevus sebaceous: report of a case.Am J Dermatopathol. 2009; 31: 658-663Crossref PubMed Scopus (22) Google Scholar1 (case report) Open table in a new tab In 1995, Cribier and Grosshans11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar reviewed 12 patients with TFI, and 3 of these patients had associated neoplasms. Two patients presented with TFI overlying a nevus sebaceus, and the third presented with TFI associated with a typical fibroma.11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar They proposed a classification system that included TFI and TFI changes associated with various tumors.11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar They found that the patient presenting with TFI associated with a typical fibroma lacked the elastic fiber network underlying the platelike proliferation of pale cells, suggesting that these were not classic TFI and, instead, TFI-like changes.11Cribier B. Grosshans E. Tumor of the follicular infundibulum: a clinicopathologic study.J Am Acad Dermatol. 1995; 33: 979-984Abstract Full Text PDF PubMed Scopus (50) Google Scholar In 2001, Mahalingam et al18Mahalingam M. Bhawan J. Finn R. Stefanato C.M. Tumor of the follicular infundibulum with sebaceous differentiation.J Cutan Pathol. 2001; 28: 314-317Crossref PubMed Scopus (26) Google Scholar noted TFI associations with nevus sebaceus, BCC, and seborrheic keratosis. After these early associations, a number of retrospective studies reviewed TFI-associated neoplasms, generating new hypotheses and challenging older postulations. In 2009, Weyers et al10Weyers W. Horster S. Diaz-Cascajo C. Tumor of follicular infundibulum is Basal cell carcinoma.Am J Dermatopathol. 2009; 31: 634-641Crossref PubMed Scopus (16) Google Scholar reviewed 24 cases of TFI, 5 of which were associated with BCC. In 2 of these cases, there were foci showing continuity between TFI and BCC components, which they believed suggested a change in differentiation of the same type of cells, rather than the chance development of an entirely unrelated lesion, as Ackerman et al22Ackerman A.B. Neoplasms With Follicular Differentiation. Lea & Febiger, Philadelphia, PA1993Google Scholar had previous postulated. During the same year, Abbas and Mahalingam2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar conducted an extensive retrospective study, reviewing cases of TFI between 1999 and 2008, with particular focus on histologic variants and associations, following 2 consecutive cases of TFI exhibiting atypia and desmoplasia. In this study, TFI was associated with cutaneous lesions in 25% of cases; specifically, TFI was found to be associated with BCC, actinic keratosis, desmoplastic malignant melanoma, junctional melanocytic nevus, trichilemmoma, and epidermal inclusion cyst.2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar With the increased amount of associated lesions observed, they suggested that TFI may be a reactive process, analogous to focal acanthyolytic dyskeratosis, epidermolytic hyperkeratosis, and cornoid lamellation.2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar Similarly, in 2015, Baquerizo et al3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar performed a retrospective study, reviewing 67 cases spanning ten years. They found 23 of 64 lesions were associated with other neoplasms, including BCC (12.5%), actinic keratosis (7.8%), epidermal cyst (3.13%), squamous cell carcinoma (3.13%), lentigo maligna (3.13%), intradermal nevus (3.13%), and syringoma (1.56%).3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar Compared with the highest rate of associated lesions in the studied performed by Abbas and Mahalingam,2Abbas O. Mahalingam M. Tumor of the follicular infundibulum: an epidermal reaction pattern?.Am J Dermatopathol. 2009; 31: 626-633Crossref PubMed Scopus (27) Google Scholar this study presented an association up to 35%.3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar They also attributed these associations to a reactive process.3Baquerizo Nole K.L. Lopez-Garcia D.R. Teague D.J. et al.Is tumor of follicular infundibulum a reaction to dermal scarring?.Am J Dermatopathol. 2015; 37: 535-538Crossref PubMed Scopus (6) Google Scholar Our case showed a TFI that seemed to arise within the dysplastic nevus as opposed to adjacent to it, suggesting the TFI may be a reactive process in the setting of melanocytic proliferation. Although many agree that TFI is a reactive process, Alomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar raised several points opposing the TFI-like reaction based on the unique features associated with TFI. Histopathologically, TFI was differentiated from BCC based on its unique staining pattern with a dense fiber network, not seen in BCC.4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar Additionally, they found that TFI lacks expression of Ber-EP4, in contrast to BCC, and that scattered Merkel cells are identified in TFI but are usually absent in BCC.4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar Based on this evidence, rather than deeming TFI a reactive process or a degeneration into BCC, as previously thought, they proposed that TFI may present with other lesions due to common folliculosebaceus origin.4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar Alomari et al4Alomari A. Subtil A. Owen C.E. McNiff J.M. Solitary and multiple tumors of follicular infundibulum: a review of 168 cases with emphasis on staining patterns and clinical variants.J Cutan Pathol. 2013; 40: 532-537Crossref PubMed Scopus (23) Google Scholar also commented on reports of classic TFI merging with areas resembling BCC. This raises questions regarding the potential for malignant transformation, which is important clinically. The transformation has been described in 2 infundibulomas to date, notably in Schintzler's account of a 38-year-old woman with eruptive TFI, and thus, long-term follow-up is encouraged in these patients.12Inaloz H.S. Inaloz S.S. Unal B. Eralp A. Coexistence of tumor of the follicular infundibulum with an unusual trichilemmal tumor.Am J Dermatopathol. 2002; 24: 406-408Crossref PubMed Scopus (11) Google Scholar Based on our review of the literature and findings in our case, many associated neoplasms have been reported, each adding to the complex pattern and histeogenesis of TIF. Becoming cognizant of the array of TFI-associated lesions can potentially elucidate the etiology of TFI.