p75 Neurotrophin receptor differentiates between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma: insights into the histogenesis of adnexal tumours based on embryology and hair follicle biology

Background Tumour development is frequently described in the basic pathology literature as a recapitulation of embryogenesis. However, a link between the embryology of the skin and the histogenesis of adnexal tumours has been largely overlooked. The low‐affinity p75 neurotrophin receptor (p75NTR) has a profound role in hair follicle biology. We therefore speculated that it is involved in the histogenesis of follicular adnexal tumours. One of the most challenging diagnoses in dermatopathology is differentiating morphoeic basal cell carcinoma from desmoplastic trichoepithelioma. Objectives To describe the expression pattern of p75NTR during cutaneous embryogenesis, in the adult hair follicle and in morphoeic basal cell carcinoma and desmoplastic trichoepithelioma. Methods Evaluation of the staining pattern for p75NTR was performed using standard immunohistochemical techniques. For comparison, we examined staining for cytokeratin 20 which highlights Merkel cells. Results All 17 desmoplastic trichoepitheliomas were immunoreactive with > 80% of the cells stained, whereas 12 of the 14 (86%) morphoeic basal cell carcinomas were p75NTR negative. In the two positive cases of morphoeic basal cell carcinoma < 30% of cells were labelled. In the late bulbous hair peg stage and in the postnatal anagen hair follicle p75NTR highlights the outer root sheath. Conclusions Our results support the classification of desmoplastic trichoepithelioma as a follicular hamartoma mimicking the outer root sheath. In contrast, the lack of p75NTR expression in morphoeic basal cell carcinoma favours a concept of this tumour as a more primitive follicular lesion with the characteristics of a carcinoma and not a hamartoma. We suggest including p75NTR as a tool in the differential diagnosis between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma.     

Desmoplastic trichoepithelioma. Clinical aspects, histology and differential diagnosis

Twelve desmoplastic trichoepitheliomas (DT) including one recurrent tumor from 9 patients are described by their clinical and histopathological features with special reference to the differential diagnostic aspects. DT typically appear as dimple lesions with raised edges in the faces of young females and histologically is composed of epithelial sheets and keratinized or calcified cysts in a desmoplastic stroma. A case showing cellular pleomorphism and followed by a relapse may represent an aggressive variant of DT. DT must be distinguished from syringoma, trichoepithelioma and especially basal cell carcinoma (BCC).     

Multiple familial trichoepitheliomas: a folliculosebaceous-apocrine genodermatosis

We reviewed the pathologic findings on a family with multiple hereditary trichoepitheliomas. Although the majority of the lesions were trichoepitheliomas, basal cell carcinomas, spiradenomas, and spiradenomas with cylindromatous foci (spiradenocylindroma) were present, representing a spectrum of lesions exhibiting folliculosebaceous (trichoepithelioma, basal cell carcinoma) and apocrine (spiradenoma, spiradenocylindroma) differentiation. Multiple familial trichoepitheliomas may be a syndrome whereby tumors develop from undifferentiated germinative cells of the folliculosebaceous-apocrine unit. Published findings regarding the genetics of this syndrome and solitary trichoepitheliomas are reviewed; although the molecular basis for the tumors has yet to be determined, current data suggest that a tumor suppressor gene may be involved.     

Immunohistologic differential diagnosis of basal cell carcinoma, squamous cell carcinoma, and trichoepithelioma in small cutaneous biopsy specimens

The distinction between squamoid basal cell carcinoma and basaloid squamous cell carcinoma (or between BCC and trichoepithelioma variants) is usually made readily on the basis of defined histological criteria. However, these differential diagnoses occasionally can pose difficult morphological problems. The stated distinctions are clinically important because the risk of progressive disease is significantly higher with squamous carcinoma of the skin than with basal cell carcinoma (BCC), and a trichoepithelioma misinterpreted as BCC burdens the patient with an inaccurate diagnosis that may result in inappropriate surgery. Recent reports have suggested that reactivity with the monoclonal antibody Ber-EP4 is capable of separating histologically similar basal cell and squamous carcinomas, and that ihe expression of bcl-2 or CD34 antigen is able to distingtush BCC from trichoepithelioma. However, corroborative studies of these contentions are few in number. In order to investigate the usefulness of the stated immunostains in the above-cited differential diagnoses, the authors analyzed 45 basal cell carcinomas and 22 squamous carcinomas, as well as 36 trichoepitheliomas. The monoclonal antibodies Ber-EP4, My10 (CD34), and anti-bcl-2 were applied to formalin-fixed paraffin sections in all cases, using a standard avidin-biotin-peroxidase complex method. Most BCCs demonstrated strong, diffuse cytoplasmic labeling with Ber-EP4 and anti-bcl-2. In contrast, the squamous carcinomas were uniformly negative for the former marker and only focally reactive for the latter in four examples. ‘Peripheral’bcl-2 staining of trichoepitheliomas was noted in 24 of 33 of the immunoreactive tumors, but the remainder were marked diffusely and similarly to most BCCs. Among the latter, immature trichoepitheliomas were diffusely reactive for this marker in 6 of 8 cases. Labeling of epithelium for CD34 failed to discriminate between any of the tumor types under evaluation, whereas staining of peritumoral stroma was characteristic of the majority of trichoepitheliomas and more than one-third of metatypical basal cell carcinomas. These data support the suggestion that Ber-EP4 and bcl-2 are useful in the separation of BCC from squamous carcinomas. Nevertheless, they also serve to caution against reliance upon bcl-2 and CD34 immunostains in attempting to distinguish BCC from trichoepithelioma in histologically enigmatic cases. There is currently no certain method other han conventional microscopy that can be applied successfully to the latter problem.     

Follicular stem cell marker PHLDA1 (TDAG51) is superior to cytokeratin-20 in differentiating between trichoepithelioma and basal cell carcinoma in small biopsy specimens

Background: Biopsies submitted to dermatopathologists are becoming increasingly smaller in size and thus the available diagnostic material is reduced. The distinction between trichoepithelioma and basal cell carcinoma remains challenging, particularly if tissue is limited. Merkel cells, which can be highlighted by means of cytokeratin‐20 (CK20) immunostaining, are used as a surrogate marker for the diagnosis of trichoepithelioma, as Merkel cells commonly colonize trichoepithelioma but are generally lacking in basal cell carcinomas. In the current study, we examined the expression of a recently characterized follicular stem cell marker, PHLDA1 (pleckstrin homology‐like domain, family A, member 1), also known as TDAG51 (T‐cell death‐associated gene 51). Methods: Using standard immunohistochemical techniques, we examined 19 trichoepitheliomas and 11 basal cell carcinomas for the expression of PHLDA1 and compared it with CK20 expression. Results: All 19 trichoepitheliomas were immunoreactive for PHLDA1 and all 11 basal cell carcinomas lacked PHLDA1 expression. Two of eleven basal cell carcinomas harbored CK20‐positive Merkel cells. Three trichoepitheliomas lacked secondary CK20‐positive cells. Conclusions: Our results suggest that PHLDA1 represents a practical and easily used tool that can be applied to the differentiation of trichoepithelioma and basal cell carcinoma in small biopsy specimens. Rather than searching for CK20‐positive Merkel cells, assessing PHLDA1 expression allows the differential diagnosis between trichoepithelioma and basal cell carcinoma to be solved at scanning magnification. 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.     

Giant solitary trichoepitheliomas located in the perianal area: a report of three cases

Very large solitary trichoepitheliomas which arose in the perianal region in three patients are described. Although these tumours showed a striking histological similarity to classical multiple or solitary trichoepitheliomas of the face, they differed in their massive size, unusual location and by their involvement of deeper tissue. We suggest that giant solitary trichoepitheliomas is a distinct variant of trichoepithelioma that may have a predilection for the perianal region. At this site this rare tumour must be distinguished from basal cell carcinoma of the perineum and from malignant basaloid (cloacogenic) carcinoma of the anal canal.     

Does the peritumoral stroma of basal cell carcinoma recapitulate the follicular connective tissue sheath?

Background: There are compelling embryologic and anatomic relationships within adnexal tumors. However, these are mostly perceived within the epithelial component while the stromal component of the tumors is frequently overlooked. In postnatal skin, nestin is almost exclusively expressed in the perifollicular mesenchyme. This study examines the expression of this neuroepithelial stem cell protein in trichoblastoma/trichoepithelioma and in basal cell carcinoma (BCC), which is increasingly being viewed as follicular in nature. Methods: We employed standard immunohistochemical methods with three different antibodies to examine the expression of nestin in 25 BCCs and compared the staining pattern with that of 7 trichoblastomas and 11 trichoepitheliomas. Results: Nestin is expressed in the peritumoral stroma of all tumors examined and is limited to the immediate layer of mesenchymal cells surrounding the tumor epithelium. In BCC, nestin‐immunoreactive cells are found as a sheath of thin, spindled fibroblasts, while reactive cells are plump in trichoepitheliomas/trichoblastomas. Conclusions: We postulate that the peritumoral stroma of BCC imitates the perifollicular connective tissue sheath, while in contrast that of trichoepithelioma/trichoblastoma is similar to the papillary and immediate peripapillary follicular mesenchyme. Further functional and animal experimental studies are needed to test this hypothesis. Sellheyer K, Krahl D. Does the peritumoral stroma of basal cell carcinoma recapitulate the follicular connective tissue sheath? A comparative analysis of nestin expression in basal cell carcinoma, trichoepithelioma, trichoblastoma and the hair follicle.     

PHLDA1 (TDAG51) is a follicular stem cell marker and differentiates between morphoeic basal cell carcinoma and desmoplastic trichoepithelioma

Background Morphoeic basal cell carcinoma (BCC) and desmoplastic trichoepithelioma can often be difficult to differentiate on routine sections and few reliable immunohistochemical markers are currently available. Recent cDNA microarray studies revealed the pleckstrin homology‐like domain, family A, member 1 protein (PHLDA1) as a highly reliable marker of the hair follicle stem cells. Given the differentiation of trichoepithelioma along the follicular lineage and the proposed role of PHLDA1 as a follicular stem cell marker, we examined the staining pattern of PHLDA1 in the desmoplastic variant of trichoepithelioma and in its differential diagnostic conundrum, morphoeic BCC. Objectives To describe the expression pattern of PHLDA1 in morphoeic BCC and desmoplastic trichoepithelioma. Methods Evaluation of the staining pattern for PHLDA1 was performed using standard immunohistochemical techniques. For comparison reasons, we analysed staining for PHLDA1 in normal skin structures with particular reference to the hair follicle. Results With the exception of one case, all 16 desmoplastic trichoepitheliomas were immunoreactive with more than 80% of the cells stained, whereas all 14 morphoeic BCCs were PHLDA1‐negative with the exception of ulcerated tumours. In the latter, the tumour islands close to the ulcer were PHLDA1‐positive whereas the deeper located tumour portions remained immunonegative. PHLDA 1 was prominently expressed in the hair follicle bulge of terminal and vellus hair follicles. Conclusions The hair follicle bulge marker PHLDA1 differentiates between desmoplastic trichoepitheliomas and nonulcerated examples of morphoeic BCCs. We suggest incorporating PHLDA1 in the diagnostic work‐up of difficult to differentiate basaloid tumours.     

Solitary familial desmoplastic trichoepithelioma. A study by conventional and electron microscopy

Solitary desmoplastic trichoepitheliomas from a mother and two daughters were studied by conventional and electron microscopy. Differential diagnosis by conventional microscopy is briefly discussed. The lesions consisted of cords and nests of basaloid cells set in fibrotic stroma and confined to the dermis. In addition, each lesion contained horn cysts and focal areas of calcification. Horn cysts were occasionally identified in continuity with infundibulae of normal hair follicles. Semithin sections showed cords and nests of cells in continuity with the horn cysts. Ultrastructurally, a continuous basal lamina surrounded the cords of basaloid cells and connected to horn cysts. Individual cells contained tonofilaments and were attached to adjacent cells by desmosomes. Hemidesmosomes were present at peripheral cell membranes bounded by basal lamina. There was no glandular differentiation. Our observations by electron and conventional microscopy support a conclusion that desmoplastic trichoepitheliomas are derived from hair appendages.     

Androgen receptor expression helps to differentiate basal cell carcinoma from benign trichoblastic tumors

Histologic differentiation between basal cell carcinoma and benign trichoblastic neoplasms such as trichoepithelioma and trichoblastoma can be difficult on small biopsies. Therefore, several attempts have been made to identify immunohistochemical differences between these entities. Recent studies have shown androgen receptor expression in a number of mature epithelial structures in the skin and in epithelial neoplasms including basal cell carcinoma. In contrast, androgen receptor expression was absent in mature hair follicles or the few trichogenic neoplasms studied to date. These findings suggested that androgen receptor expression might be a useful adjunct in the histologic differential diagnosis between basal cell carcinoma and benign trichoblastic neoplasms. Therefore, we performed immunohistochemical analysis of androgen receptor expression in 32 basal cell carcinomas and 10 benign trichoblastic tumors (6 trichoepitheliomas and 4 trichoblastomas). In our study, at least focal expression of androgen receptor was detected in 78% of basal cell carcinomas. None of the trichoblastic tumors showed any androgen receptor immunoreactivity. These results confirm the lack of expression of androgen receptor in benign trichoblastic neoplasms and indicate that androgen receptor expression by tumor cells points to basal cell carcinoma as the most likely diagnosis.     

Monoclonal antibody Ber-EP4 reliably discriminates between microcystic adnexal carcinoma and basal cell carcinoma

BACKGROUND: Sclerosing cutaneous neoplasms often represent a diagnostic challenge. The monoclonal antibody Ber-EP4 recognizes two glycopolypeptides found in most human epithelial cells. It is diagnostically highly reliable in the differentiation between basal cell carcinoma and cutaneous squamous cell carcinoma. In this study, we report its application in the differential diagnosis of microcystic adnexal carcinoma, desmoplastic trichoepithelioma and basal cell carcinoma. METHODS: Biopsy samples from 28 sclerosing and infiltrating basal cell carcinomas, 13 microcystic adnexal carcinomas and 16 desmoplastic trichoepitheliomas were examined after immunohistochemical staining with Ber-EP4. RESULTS: Ber-EP4 did not label any of the microcystic adnexal carcinomas, whereas all 28 basal cell carcinomas were Ber-EP4 positive. Twenty-seven of the 28 showed moderate or strong staining intensity, with the majority being strong. Only one basal cell carcinoma was weakly positive. Twelve of the 16 desmoplastic trichoepitheliomas were immunoreactive with Ber-EP4 and the staining was more variable than those of basal cell carcinomas. CONCLUSIONS: Ber-EP4 reliably differentiates microcystic adnexal carcinoma from basal cell carcinoma to the same extent as it distinguishes the latter tumor from squamous cell carcinoma. While it stains the majority of desmoplastic trichoepitheliomas, these tumors still have to be considered in the differential diagnosis with microcystic adnexal carcinoma, when Ber-EP4 is applied.     

Merkel cells are integral constituents of Desmoplastic trichoepithelioma: an immunohistochemical and electron microscopic study

The incidence of Merkel cells has previously been investigated in a number of inflammatory and tumorous lesions of the skin. Special attention was given to tumors with follicular differentiation. In the present study we examined the localization of Merkel cells in another adnexal tumor, the desmoplastic trichoepithelioma (n= 15), as well as in its main differential diagnosis, the morpheiform basal-cell carcinoma (n=30). Using immunohistochemical methods, we found Merkel cells as a stable constituent in desmoplastic trichoepitheliomas, but failed to detect them in morpheiform basal-cell carcinomas. These findings might therefore be an important tool in the sometimes very difficult but clinically imperative distinction between these two conditions. Furthermore, our study may be of interest in the discussion about the origin of desmoplastic trichoepitheliomas. High numbers of Merkel cells in desmoplastic trichoepitheliomas indicate a bulge-derived origin of this adnexal tumor, since high numbers of Merkel cells, especially in the bulge, were recently discovered. Although the significance of Merkel cell hyperplasia in desmoplastic trichoepithelioma is not presently understood, a regulatory role of the Merkel cell in growth and development of this adnexal tumor is suggested.     

Multiple hereditary infundibulocystic basal cell carcinomas: a genodermatosis different from nevoid basal cell carcinoma syndrome.

BACKGROUND: Infundibulocystic basal cell carcinoma is a recently described distinctive clinicopathologic variant of basal cell carcinoma. Histopathologic differential diagnosis among infundibulocystic basal cell carcinoma, trichoepithelioma, and basaloid follicular hamartoma has generated controversy in the literature. OBSERVATIONS: Members of 2 families with multiple infundibulocystic basal cell carcinomas are described. Each patient showed multiple papular lesions, mostly located on the face. No patient showed palmar pits or jaw cysts. Forty-two cutaneous lesions from 5 patients were studied histopathologically. Thirty-nine lesions were infundibulocystic basal cell carcinomas. This clinicopathologic variant of basal cell carcinoma consists of a relatively well-circumscribed basaloid neoplasm composed of buds and cords of neoplastic cells arranged in anastomosing fashion and with scant stroma. Some of the neoplastic cords contain tiny infundibular cysts filled by cornified cells with abundant melanin. Linkage analysis in family 2 was performed using polymorphic markers (D9S196, D9S280, D9S287, and D9S180), and the affected members shared the same haplotype. Loss of heterozygosity analysis was performed in 2 affected members of this family from whom tumoral DNA was available, and although these individuals were constitutively heterozygous for D9S196, they did not show loss of heterozygosity for this marker in their neoplasms. CONCLUSIONS: Multiple hereditary infundibulocystic basal cell carcinomas represent a distinctive genodermatosis different from multiple hereditary trichoepitheliomas and nevoid basal cell carcinoma syndrome. We propose clinical and histopathologic criteria to distinguish infundibulocystic basal cell carcinoma from trichoepithelioma, basaloid follicular hamartoma, and folliculocentric basaloid proliferation.     

Trichogerminoma: a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium

In 1992, Sau and colleagues described 14 cases of a rare cutaneous adnexal tumor with differentiation toward the hair germ epithelium. All cases in their study displayed a unique constellation of histological features which allowed the authors to consider the neoplasm to be a distinct entity and to designate it as 'trichogerminoma' (TG). We present a case of an adnexal tumor identical to that described as TG and report the immunophenotypical features of this neoplasm for the first time. A biopsy from a 41-year-old man revealed a well-demarcated epithelial tumor composed of multiple lobules located in the deep dermis without connection to the overlying epidermis and surrounded by a fibrous pseudocapsule. The tumorous lobules were composed of uniform basophilic cells with vesicular nuclei, dispersed chromatin and prominent nucleoli showing no prominent peripheral palisading. Some of the lobules had the appearance of densely packed 'cell balls' with peripheral condensation of the tumor cells. The stroma showed a moderate number of fibroblasts and mast cells. Reticulum staining revealed fine reticulum fibers surrounding the tumor aggregates with accentuation of the 'cell balls'. Immunohistochemically, the tumor cells expressed AE1/AE3, CK5/8, CK5/6, CAM5.2 and stained negatively for CK20, CK7, calretinin, Lu-5 and Thomsen- Friedensreich antigen. There was no increase in the numbers of CK20-positive Merkel cells in the epidermis overlying the tumor; however, a few Merkel cells were scattered in some tumor lobules. In addition, we stained 6 trichoblastomas (TBs) and found a particular pattern of calretinin expression in this tumor which was not observed in our case of TG. We conclude that pathological features allow the delineation of TG as a distinct adnexal neoplasm. Histological differential diagnosis includes basal-cell carcinoma (pilar type), large nodular TB, trichoblastic fibroma, trichoepithelioma, tricholemmoma, pilomatricoma and matrical carcinoma.     

Trichogerminoma

We report 14 cases of trichogerminoma, a rare form of cutaneous adnexal neoplasm, derived from hair germ epithelium. The neoplasms occurred in 9 men and 5 women. Their ages ranged from 16 to 73 years (median 53 years). The tumors were slow growing, asymptomatic dermal or subcutaneous nodules, located on the head and neck (6), trunk (4), extremities (2) and hip (1), with no distinguishing clinical features. Histologically, trichogerminomas were characterized by sharply circumscribed, pseudoencapsulated dermal and subcutaneous nodules, ranging in size from 0.4 to 4.0 cm in diameter (mean 1.9 cm). The nodules were subdivided into lobules separated by variable amounts of stroma that demonstrated varying cellularity and mucin content. The lobules were composed of basaloid cells that formed densely packed, round nests or "cell balls" resembling hair bulbs. The basaloid cells demonstrated peripheral palisading, keratinization and differentiation towards various pilosebaceous structures. Retraction spaces, well developed hair follicles and hair shafts were not observed. These distinctive histologic features separated these neoplasms from other tumors of pilar origin and from basal cell carcinoma. The trichogerminomas behaved in a benign fashion with one exception. Complete excision of the lesions is the treatment of choice.     

Dermal fibrous histiocytoma with inductive formation of a partially pigmented basalioma of the trichoepitheliomatous type

Report about a 73 years old woman with a rare dermal tumor of the right shoulder. Histological examination of the tumor shows a pigmentary basal cell carcinoma on type of trichoepithelioma overlying long-standing dermal fibrous histiocytoma.     

Expression of the hair stem cell-specific keratin 15 in pilar tumors of the skin.

Keratin 15 (K15) was recently shown to be a specific marker of stem cells of the hair-follicle bulge. We studied the reactivity of an antibody to the CD8 antigen (C8/144B), recognizing K15, on 66 cutaneous tumors with known or alleged pilar differentiation, in order to assess its usefulness in the diagnosis of this group of tumors. 2/2 basal cell nevi, 5/8 trichoepitheliomas and 1/3 trichofolliculomas showed substantial reactivity. Much weaker reactivity was observed in cases of trichilemmal tumors (trichilemmomas and trichilemmal cysts); by contrast, all cases of pilomatricomas, basal cell carcinomas and epidermoid cysts were completely unreactive. These results are in keeping with the admitted differentiation of the tumors studied, and suggest further that basal cell carcinomas do not differentiate towards hair bulge cells. From a practical point of view, immunostaining for K15 seems to be an additional useful adjunct for the differential diagnosis between basal cell carcinoma and trichoepithelioma.     

Composite Tumor Associating Trichoblastoma and Seborrheic Keratosis

Seborrheic keratosis is a common benign epidermal tumor histologically composed of basaloid and squamous cells. It mainly occurs on the face, scalp, and trunk, and presents clinically as a well-circumscribed, brownish to black papule, nodule, or plaque. Trichoblastoma is a relatively rare benign, slow-growing tumor showing differentiation toward the primitive hair follicle. It clinically manifests as a solitary, skin to erythematous colored, well-circumscribed dermal nodule located predominantly on the head and neck with a predilection for the scalp. Histologically, a well-demarcated mass of follicular germinative cells that show various degrees of differentiation, arranged in lobules, sheets, and nests, is located in the dermis or subcutaneous fat layer. We report the case of a 28-year-old female patient with a solitary, 2.0×4.0-cm black plaque with a 0.7-cm skin-colored nodule on the scalp. Histologically, the entire black plaque had prominent hyperkeratosis, acanthosis, and papillomatosis with horn cysts. The central nodule showed well-circumscribed, various-sized dermal tumor lobules without a connection to the overlying epidermis. The lobular aggregation was composed of numerous basaloid epithelial nests and multiple primitive papillary structures with distinct peripheral palisading of nuclei. According to these findings, the scalp lesion was diagnosed as a composite tumor associating trichoblastoma and seborrheic keratosis.     

Inguinal keratotic Basal cell carcinoma mimicking giant solitary trichoepithelioma

Keratotic basal cell carcinoma may not only clinically but also histologically share more or less the same features with giant solitary trichoepithelioma. It can be difficult to distinguish these two entities from each other, even for an experienced dermatopathologist. We present an unusual case of inguinal keratotic basal cell carcinoma mimicking giant solitary trichoepithelioma in a 56-year-old woman with a finger-like tumor of 20 years duration. The patient presented with an asymptomatic, skin colored, firm, nonulcerative, nodular lesion. Scanty mitotic activity and apoptotic cells were the histopathologic findings against basal cell carcinoma, whereas absence of papillary mesenchymal bodies, presence of peritumoral lacunae detected only around the solid areas, and accumulation of amyloid-like hyalinized material were the findings in favor of basal cell carcinoma. This case illustrates that keratotic basal cell carcinoma must be taken into account in the differential diagnosis of inguinally located solitary, polypoid masses, especially giant solitary trichoepithelioma.     

Twelve Years’ Observation of Multiple Familial Trichoepithelioma with Squamous Carcinoma

Long-standing trichoepithelioma lesion on scalp with 12 years follow-up. The patient was observed for 12 years, and the carcinoma recurred 3 times during 8 years after surgical excision and radiation therapy. Malignant transformation may occur in multiple familial trichoepitheliomas; Moderate radiation therapy should be given for malignant transformation patients with lower radiation dose and shorter time. Removing the trichoepithelioma as soon as possible if the tumor suddenly or continuously increased is recommended.