Adnexal Tumors in Children Clinically Mimicking Basal Cell Carcinoma

Home , Nevus sebaceous, Pilomatricoma, Trichilemmoma, Trichoblastoma, Trichoepithelioma, Trichofolliculoma

Eur. J. Pediat. Dermatol. 25, 7-11, 2015

Adnexal tumors in children clinically mimicking basal cell carcinoma.

Puente-Pablo N.*, Tardío J.C.**, Nájera L.**, Hernández-Núñez A.*, Freites-Martínez A.*, Borbujo J.M.* *Department of Dermatology, ** Department of Pathology Fuenlabrada University Hospital, Fuenlabrada, Madrid, Spain

Summary Trichoblastoma and trichofolliculoma are unusual adnexal tumors in the pediatric population. As clinical presentation is unspecific, misdiagnosed cases as basal or squamous cell carcinoma are described. Besides, histological differentiation between basal cell carcinoma and trichoblastoma is also difficult. As long as trichoblastoma and trichofolliculoma are benign tumours, treatment is optional. However, complete excision of trichoblastoma is often advised since it can continue growing. Relapse or malignant transformation of solitary lesions is unusual. Here are reported two pediatric cases of typically adult follicular tumors.

Key words Trichofolliculoma, trichoepithelioma, trichoblastoma, children, childhood, adnexal, neo- plasm.

richoblastoma (TB) and trichofolliculoma months ago, with occasional serous drainage. (TF) are unusual adnexal tumors which Physical examination showed a translucent flesh- occur in adults between 20 and 50 years. colored papule measuring 4 mm in diameter on TIn the pediatric population up to 16-years old, ala nasi (Fig. 1). The microscopic evaluation of there are 13 cases of TF and 18 of TB - some of punch biopsy revealed multiple islands of basa- them congenital - reported in the literature in the loid cells associated with fibrous stroma. Papil- last 20 years. lary mesenchymal bodies could be appreciated Clinical presentation is unspecific as solitary (Fig. 2). TB was diagnosed. asymptomatic papules or nodules located around Case 2. A 4-year–old girl with no relevant me- nose or upper trunk, and microscopic examina- dical history presented with a congenital right tion is needed to confirm diagnosis. Complete supraciliary lesion; the latter was responsible for excision is recommended since they can conti- local unspecific discomfort. On physical exami- nue growing if incompletely excised. Relapse nation, an indurated erythematous and yellowish or malignant transformation of solitary lesions is papule measuring 3 mm in diameter was found rare. (Fig. 3). The microscopic evaluation of a punch Dermatologists should be aware of these ad- biopsy showed a dilated hair follicle with infun- nexal tumours as basal or squamous cell carcino- dibular type keratinisation and epidermal con- mas are sometimes misdiagnosed. nection. The cavity contained keratinous debris. Numerous secondary follicles and mature sebaceous lobules arising from the cystic wall could Case report be observed (Fig. 4). A histopathological diagnosis of TF was made. Case 1. A 10-year-old girl with no relevant In both cases no relapses or new lesions were medical history referred a facial lesion from 8 found after 10 months of follow-up.

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Fig. 1 Fig. 2 Fig. 1, 2: Trichoblastoma: translucent flesh-colored papule on ala nasi (Fig.). The histological examination (Fig. 2) showed nests and sheets of basaloid cells with peripheral palisading, surrounded by fibroblastic stroma. In some areas, the neoplastic cells showed hair follicle differentiation (Hematoxylin & Eosin, 40x).

Fig. 3 Fig. 4 Fig. 3, 4: Indurated erythematous and yellowish supraciliary papule (Fig. 3). In Fig. 4: trichofolliculoma: cystically dilated infundibulum with several secondary hair follicles and mature sebaceous lobules radiating from its wall (Hematoxylin & Eosin, 40x).

Discussion tial pathologic feature: the probable origin from uncontrollated proliferation of follicular germi- After literature review, there are 13 cases of native pluripotential cells (trichoblasts). TF and 18 of TB described in the last 20 years in TF is a follicular hamartoma and it is believed children. to represent abortive differentiation of pluripo- Ackerman et Al. (6) proposed the term “tricho- tent cells toward follicles (4). blastoma” to include all benign cutaneous tumors The clinical presentation is unspecific in both composed predominantly by follicular germina- tumours, usually as acquired, slow-growing and tive cells. According to the cellular arrangement, solitary papules or nodules, rubbery to firm in TB are divided into large nodular, small nodular, consistency, pearled and smooth with flesh-colo- cribiform, retiform, columnar and racemiform red, erythematous or brownish surface. patterns. Most of them correspond to various They typically appear on the central face around types of the old term trichoepithelioma. There is nose or on the upper trunk, and are asymptoma- still controversy about terminology, but we have tic. Sometimes a central ostium may be identifia- used the term TB because it represents the essen- ble in TF and a small wool-like tuft of hairs may

8 Adnexal tumours in children clinically mimicking basal cell carcinoma protrude from the surface; the latter finding gives dermal cyst, molluscum contagiosum, basaloid a distinctive clinical appearance to TF (4). follicular hamartoma or adnexal tumors such as Congenital, giant, zosteriform, pigmented or pilomatricoma, trichilemmoma or syringoma and subcutaneous TB and TF have been reported, basal and squamous cell carcinomas. Ruling out as well as intranasal, palpebral or located in the these carcinomas is important due to their diffe- arms, vulva, scrotum or penis. There are several rent prognosis. reports of TB associated with nevus sebaceous, Basal cell carcinoma is quite rare in the pe- blue nevus or melanocytic nevus, and of TF as- diatric population (9). In a large study of 36,207 sociated with angiomyxoma or basal cell carci- children with skin disorders done by De la Luz noma. Orozco-Covarrubias et Al. (3), only 7 basal cell Most TB are solitary and acquired lesions, and carcinomas were found (13% of all malignant cu- almost one half of the studied lesions show dele- taneous tumors found). Therefore, the incidence tions on chromosome 9q22.3 at the Drosophila of basal cell carcinoma was only 1.9 in 10,000 patched gene (8). Multiple TB may occur linked dermatological patients. In 2007, a thorough lite- with 9p21 mutations leading to multiple familial rature review revealed 107 children with idiopa- trichoepithelioma entity or linked to chromoso- thic basal cell carcinoma (10). me 16q12-q13, which harbors the recessive on- In the absence of a genetic disorder such as Ba- cogene cylindromatosis associated with Spiegler- zex syndrome, albinism, basal cell nevus syndro- Brooke syndrome (8). me, xeroderma pigmentosum or nevus sebaceous Desmoplastic trichoepithelioma is a rare TB (14), it is often difficult to identify a predispo- variant that usually presents as a slowly growing, sing factor (15). Only some patients had a clini- isolated, firm, annular lesion with raised borders cal history of risk factors such as frequent and/or and non-ulcerating centre on the cheek. Its major prolonged sun exposure, sunburns (5), radiation clinical and pathological differential diagnosis is therapy, vitiligo or immune suppression due to morphea-like basal cell carcinoma (12). acquired immunodeficiency syndrome, drugs or On the other side, nearly all cases of TF have transplantation (14). Basal cell carcinoma has a been reported as single lesions, although three more aggressive phenotype when arising in early cases described by Nomura and Hata, Cohen and life as compared with adulthood (14). Davis and Chang-Min Choi et Al. were multiple Besides, histological differentiation between (2). basal cell carcinoma and TB is also difficult: both Taking into account their unspecific clinical are composed of basaloid islands that may exhi- presentation, microscopic examination is needed bit peripheral palisading, but in most basal cell to make the right diagnosis. carcinomas basaloid islands retract from the adja- TB shows well-circumscribed dermal nodule cent stroma and mucina can be appreciated in the composed of nests and sheets of basaloid cells clefts; the latter are rare in TB. Besides, TB shows with peripheral palisading and surrounded by an papillary mesenchymal bodies, which are believed exuberant fibroblastic stroma. In some areas of to represent rudimentary follicular bulbs, papillar the tumor, neoplastic cells show hair follicle dif- keratin cysts and an increased number of Merkel ferentiation. cells, which are absent in basal cell carcinomas TF histopathological findings consist of a di- (6). lated keratin-filled hair follicle with immature Lichtenstein et Al. (11) reported a TB misdia- secondary and tertiary follicles radiating from its gnosed as basal cell carcinoma in an 8-year-old wall. Well-differentiated follicles produce fine, child and Pignatti et Al. (13) described a desmo- colorless hair. An organized fibrovascular stroma plastic trichoepithelioma as a squamous cell car- surrounds the epithelial structures, giving TF a cinoma in a 12-year-old patient. well defined nodular appearance. In the last years Ardigo et Al. (1) and Khelifa et Clinical differential diagnosis of both TB and Al. (7) described some dermoscopy clues to dif- TF is wide because of the unspecific presentation, ferentiate desmoplastic trichoepitheliomas from and includes intradermal melanocytic nevus, epi- basal cell carcinomas: although desmoplastic tri-

9 Puente-Pablo et Al. choepitheliomas might show arborizing telangie- Relapse or malignant transformation of solita- ctasias, they do not exhibit leaf-like structures or ry lesions is rare, and even rarer in children (6) ovoid nests and they do present a well-defined although malignant and aggressive TB and peri- ivory-white background and some cystic structu- neural invasive TF have been sometimes descri- res. bed. Both TB and TF are adnexal benign tumours, In conclusion, we report herein two pediatric so treatment is optional. Complete excision of cases of typically adult follicular tumours. Only TB is often advised since it can continue growing few similar cases are described in pediatric pa- when incompletely excised. Shaving, electrode- tients. Dermatologists should be aware of these siccation or laser are other options although there adnexal tumours as they should be differentiated are few cases reported. from basal or squamous cell carcinomas.

Address to: Dr. Nieves Puente de Pablo Hospital Universitario de Fuenlabrada Calle Camino del Molino n. 2 28942 Fuenlabrada, Madrid e-mail: [email protected] [email protected]

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