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Year : 2015  |  Volume : 60  |  Issue : 4  |  Page : 394-396
Trichoepithelioma and basal cell carcinoma with squamous differentiation: Is it causal or coincidental?

1 Department of Pathology, PGIMER, Dr. RML Hospital, New Delhi, India
2 Department of Dermatology, PGIMER, Dr. RML Hospital, New Delhi, India

Date of Web Publication10-Jul-2015

Correspondence Address:
Dr. Arvind Ahuja
Department of Pathology, PGIMER, Dr. RML Hospital New Delhi - 110 001
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0019-5154.160494

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Trichoepitheliomas (TEs) are benign cutaneous tumors that occur either as solitary non-familial or multiple familial. We report a case of multiple familial trichoepithelioma (MFT) in a 55-year-old female patient and her son who came with complaints of single ulcerated mass involving the left nasolabial fold and cheek. She had multiple papules and nodules all over the face and neck since 25 years. Histopathological examination of an ulcerated lesion revealed features of basal cell carcinoma (BCC) with squamous differentiation, which was confirmed by immunohistochemistry. A skin biopsy obtained from the papule on neck showed features of TE. However, whether BCC developed independently or by transformation from TE was uncertain. Her 36-year-old son presented with similar lesions on the face and a skin biopsy showed features of TE. Though malignant transformation of TE is quite rare, awareness of the potential for evolution of carcinoma in patients with MFT is important for management of these patients.

Keywords: Basal cell carcinoma, immunohistochemistry, multiple familial trichoepithelioma, squamous differentiation, trichoepithelioma

How to cite this article:
Agarwal P, Agarwal C, Bhardwaj M, Ahuja A, Rani S. Trichoepithelioma and basal cell carcinoma with squamous differentiation: Is it causal or coincidental?. Indian J Dermatol 2015;60:394-6

How to cite this URL:
Agarwal P, Agarwal C, Bhardwaj M, Ahuja A, Rani S. Trichoepithelioma and basal cell carcinoma with squamous differentiation: Is it causal or coincidental?. Indian J Dermatol [serial online] 2015 [cited 2021 Jun 16];60:394-6. Available from: https://www.e-ijd.org/text.asp?2015/60/4/394/160494

What was known?

  • TE rarely undergoes malignant transformation commonly into BCC.
  • BCC and TE are diagnostic challenges in terms of their differential diagnosis.

   Introduction Top

Trichoepitheliomas (TEs) are regarded as poorly differentiated hamartomas of hair germ [1] , located mainly on face, nasolabial folds, forehead, upper lip and scalp. [2] There are three variants of TE: Solitary, multiple and desmoplastic. Multiple familial trichoepithelioma (MFT), also known as epithelioma adenoides cysticum, present as small papules with strong predilection for central part of the face. The onset of lesions is usually in childhood or at the time of puberty. [1]

TE is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). Malignant transformation of such lesions is quite rare. [2],[3],[4] It is important to distinguish these neoplasms. [5] BCC and TE are diagnostic challenges in terms of their differential diagnosis. [6] Limited immunohistochemical stains are available to separate them. [5]

   Case Report Top

A 55-year-old female came to dermatology outpatient department with a single ulcerated mass measuring 5 × 4 cm, involving left nasolabial fold and cheek. The lesion had developed 3 years back. Base of the ulcer was covered with granulation tissue. She also had multiple asymptomatic, small, firm, skin-colored papules and nodules all over the face and neck since 25 years [Figure 1]a]. General physical and systemic examination revealed no abnormality. Routine laboratory investigations were within normal limits. There was no history of consanguinity in the family. A skin biopsy was performed from both the ulcerated mass and one of the papules present on the neck.
Figure 1: (a) Clinical presentation of mother having multiple papulonodular lesions on the face with ulcerated mass involving the left nasolabial fold and cheek. (a) Histopathology of the papule present on the neck of the mother showing trichoepithelioma (H and E, ×40)

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Histopathological examination of the ulcerated mass showed focal ulceration of epidermis with underlying tumor composed of basaloid cells in nests, cords and solid sheets in a myxoid background [Figure 2]a]. Focal peripheral palisading and retraction artifact was also seen [Figure 2]b]. The cells were small, monomorphic with round to oval hyperchromatic nuclei and scant cytoplasm. Squamous differentiation was seen within some of the cell nests [Figure 2]c]. Frequent mitosis was present with focal areas of necrosis [Figure 2]d]. Intervening stroma showed acute and chronic inflammatory cells. On immunohistochemistry (IHC), basaloid cells were positive for Bcl2 (diffuse, [Figure 3]a) and CD10 [Figure 3]b]. CD34 was negative in the stromal as well as the epithelial cells [Figure 3]c] while an epithelial membrane antigen (EMA) was positive in the squamous cells [Figure 3]d]. Based on these findings, a diagnosis of basal cell carcinoma with squamous differentiation was rendered.
Figure 2: Histopathology of the ulcerated lesion present on the left nasolabial fold. (a) Basal cell carcinoma with focal ulceration (H and E, ×40). (b) Basaloid cells with peripheral palisading and retraction artifacts (H and E, ×100). (c) Squamous differentiation (H and E, ×400). (d) Mitosis (H and E, ×400)

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Figure 3: Immunohistochemistry using antibodies directed against (a) Bcl2 (IHC, ×100), (b) CD10 (IHC, ×200), (c) CD34 (IHC, ×100) and (d) EMA (IHC, ×200)

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A skin biopsy from a papule on the neck showed a circumscribed tumor in dermis composed of multiple keratin-filled horn cysts surrounded by basaloid cells and solid aggregates with peripheral palisading surrounded by proliferating fibroblasts. No mitosis was seen. Overlying epidermis showed mild thinning. A diagnosis of TE was made [Figure 1]b].

Her son who is 36 year old presented with similar multiple papulonodular lesions all over the face since childhood [Figure 4]a]. A skin biopsy from the lesion showed features of TE [Figure 4]b].
Figure 4: (a) Clinical presentation of the son having multiple papulonodular lesions on the face. (b) Histopathology of the lesion on the face of the son showing trichoepithelioma (H and E, ×40)

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   Discussion Top

TE is a benign neoplasm of follicular germinative cells. Clinically, this tumor occurs either as a solitary lesion without familial association or as multiple lesions in MFT. [2] MFT have an autosomal dominant mode of inheritance, with lessened expressivity and penetrance in a male. [1] The putative gene for MFT has been localized to chromosome 9p21. [6]

The lesions of TE are characterized by firm skin-colored papules or nodules 2 to 8 mm in size, mainly concentrated around the nasolabial folds and forehead. The lesions first appear in childhood and may grow larger and increase in number over time. In the present case the patient and her son had similar lesions all over the face since childhood, thereby suggesting familial disease.

TEs are superficial dermal lesions with focal continuity with the epidermis. [1] Small keratinous cysts lined by basaloid cells are the most characteristic histologic feature. Also, present are islands of uniform basaloid cells, showing peripheral palisading. The fibroblasts encircle these islands, which lack retraction artifact typical of BCC. These solid aggregates show invaginations which contain numerous fibroblasts and resemble follicular papillae also known as papillary mesenchymal bodies.

TE causes only cosmetic disfigurement to the patients but occasionally BCC can develop in association with it. [2],[3],[4] Histologically, the presence of horn cysts, papillary-mesenchymal bodies, lack of atypia and mitoses along with a cribriform pattern and stromal fibrosis favor a diagnosis of TE, whereas the presence of mucin, stromal edema and retraction artifact around the basaloid islands and mitoses suggest a diagnosis of BCC.

However, the distinction between BCC and TE on histopathological basis is quite difficult. IHC has been considered for the differential diagnosis. [7] TE shows CD10 stromal immunoreactivity, while in BCC staining involves basaloid cells. Focal positive CD34 staining of fibroblastic stroma has been shown in TE, whereas in BCC, this staining pattern is not seen but it may be seen in BCC with squamous differentiation (metatypical). Staining of the outermost epithelial layer for Bcl2 has been seen in TE. In contrast, BCC frequently stains diffusely for Bcl2 [Table 1]. [7] Follicular stem cell marker, PHLDA1 (pleckstrin homology-like domain, family A, member 1), also known as TDAG51 (T-cell death-associated gene 51), and CK20 are positive in TE and negative in BCC. [8] Malignant transformation of TE to BCC is very rare. Nevertheless, there have been few cases of BCC arising in the setting of multiple TEs. [7] In the present case, patient had features of multiple TEs along with an ulcerated lesion showing features of BCC with squamous differentiation, a subtype not reported in the previous published literature. [2],[3],[4] Whether BCC developed independently or by transformation from TE was uncertain.
Table 1: Immunohistochemical markers to differentiate TE and BCC

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The close relationship between TE and BCC has been explained on the basis of assumption that they have a common genesis from pluripotential cells, which, like primary epithelial germ cells, may develop toward hair structures. This hypothesis is supported by the fact that PATCH gene mutations are seen in both tumors. [7] Recently, cylindromatosis tumor suppressor gene (CYLD) mutation is also seen in MFT. [3]  Brooke-Spiegler syndrome More Details is a rare autosomal dominant disorder caused by mutations of the CYLD gene resulting in multiple cylindromas and TEs. [9]

Any suspicion of malignant change which is indicated by rapid growth and ulceration in the pre-existing lesion calls for excision and histological examination. [10] TE is a benign lesion that may be excised with a small margin of healthy tissue, thereby facilitating surgical repair; however, BCC is the locally malignant tumor treated by excision with 3-4 mm margins. Hence, the differentiation between both the lesions is mandatory.

To conclude, awareness of the potential for the evolution of carcinoma in patients with MFT is important for further management.

   References Top

Weedon D. Weedon's skin pathology. Section 7 Tumors. London: Elsevier Publications, Churchill livingstone; 2010. p. 760-2.  Back to cited text no. 1
Samaka RM, Bakry OA, Seleit I, Abdelwahed MM, Hassan RA. Multiple familial trichoepithelioma with malignant transformation. Indian J Dermatol 2013;58:409.  Back to cited text no. 2
[PUBMED]  Medknow Journal  
Pincus LB, McCalmont TH, Neuhaus IM, Kasper R, Oh DH. Basal cell carcinomas arising within multiple trichoepitheliomas. J Cutan Pathol 2008;35:59-64.  Back to cited text no. 3
Lee KH, Kim JE, Cho BK, Kim YC, Park CJ. Malignant transformation of multiple familial trichoepithelioma: Case report and literature review. Acta Derm Venereol 2008;88:43-6.  Back to cited text no. 4
Pham TT, Selim MA Jr. Burchette JL, Madden J, Turner J, Herman C. CD10 expression in trichoepithelioma and basal cell carcinoma. J Cutan Pathol 2006;33:123-8.  Back to cited text no. 5
Fernandez-Flores A. Advanced differentiation in trichoepithelioma and basal cell carcinoma investigated by immunohistochemistry against neurofilaments. Folia Histochem Cytobiol 2009;47:61-4.  Back to cited text no. 6
Elder DE, Elenitsas R, Johnson BL, Murphy GF, Xu X. Lever's Histopathology of the skin. 10 th ed. Tumors of the epidermal appendages. Philadalphia: Lippincott Williams and Wilkins; 2009. p. 857-9.  Back to cited text no. 7
Sellheyer K, Nelson P, Follicular stem cell marker PHLDA1 (TDAG51) is superior to cytokeratin-20 in differentiating between trichoepithelioma and basal cell carcinoma in small biopsy specimens. J Cutan Pathol 2011;38:542-50.  Back to cited text no. 8
Doherty SD, Barrett TL, Joseph AK, Brooke-Spiegler syndrome: Report of a case of multiple cylindromas and trichoepitheliomas. Dermatol Online J 2008;14:8.  Back to cited text no. 9
Kaur T, Puri KJ, Chahal KS, Budhwar J. Multiple Familial Trichoepitheliomas: A case report and review. Egypt Dermatol Online J 2012;8:11.  Back to cited text no. 10

What is new?

  • In a patient with multiple TE, any new lesion with progressive growth or ulceration should undergo biopsy to rule out malignancy.
  • Malignant transformation of TE to BCC with squamous differentiation is not reported yet in the literature.


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

  [Table 1]


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