Congenital linear unilateral basal cell nevus: a case report with patched gene molecular studies

BACKGROUND: Linear unilateral basal cell nevus represents a linear collection of macules and papules histologically similar to basal cell carcinoma but with benign clinical behavior. We describe a patient who initially presented at the age of 6 months with a unilateral linear basal cell nevus on the right flank. The differential diagnosis included the nevoid basal cell carcinoma syndrome. Constitutional PTCH mutations are causative of the nevoid basal cell carcinoma syndrome, and somatic PTCH mutations are found in the vast majority of basal cell carcinomas. Somatic SMO mutations have also been found in some basal cell carcinomas. METHODS: Histologic examination of the lesions is performed. Short tandem-repeat molecular analysis at the PTCH locus and sequencing of PTCH and SMO genes is performed. RESULTS: Histologic examination revealed features initially indistinguishable from basal cell carcinoma. Short tandem-repeat DNA analysis did not reveal loss of heterozygosity at the PTCH locus. DNA sequencing of both the PTCH and the SMO genes from the patient's lesions revealed neither inactivating mutations of PTCH nor activating mutations of SMO. CONCLUSION: Molecular examination indicates that the PTCH and SMO genes are not involved in the pathogenesis of the patients' congenital linear unilateral basal cell nevus. Furthermore, we discuss the relationship between linear basal cell nevus and basaloid follicular hamartoma.     

Linear unilateral basal cell nevus: a benign follicular hamartoma simulating multiple basal cell carcinomas

We report a case of linear unilateral basal cell nevus (LBCN) occurring on the left lateral neck and left posterior shoulder of a 23-year-old woman. LBCN is a rare benign follicular hamartoma that must be distinguished from the more aggressive unilateral and segmental variant of nevoid basal cell carcinoma syndrome (NBCCS) and the linear variant of BCC.     

Congenital smooth muscle hamartoma. A report of six cases and a review of the literature

Congenital smooth muscle hamartoma (CSMH) represents a proliferation of randomly oriented dermal smooth-muscle bundles. Six patients with CSMH were observed, the largest series to date, and the literature was reviewed. Congenital smooth muscle hamartoma has presented as congenital patches or slightly indurated plaques with prominent overlying hair (88% of cases), or rarely as patches with perifollicular papules without prominent hair (12% of cases). Most lesions (61% of cases) have been somewhat hyperpigmented, but 39% of cases have been flesh colored. Congenital smooth muscle hamartoma has occurred on the torso and proximal extremities, except for one case on the eyebrow and eyelid (present study). A positive pseudo-Darier's sign (temporary induration or piloerection after rubbing) helped to differentiate CSMH from congenital hairy nevo-cellular nevus. Congenital smooth muscle hamartoma is a distinct entity that is at one end of a spectrum that includes Becker's nevus, and should be considered in the differential diagnosis of any congenital hairy lesion.     

Trichoblastoma is the most common neoplasm developed in nevus sebaceus of Jadassohn: a clinicopathologic study of a series of 155 cases

Nevus sebaceus of Jadassohn is a hamartoma that combines epidermal, follicular, sebaceous, and apocrine gland abnormalities. Classically, several types of cutaneous neoplasms have been associated with this hamartoma, with basal cell carcinoma being the most frequently described malignancy. We studied a series of 155 examples of nevus sebaceus of Jadassohn with clinicopathologic correlation. Several histopathologic changes related to the age of the patients were found. In our series, we could not identify any cases of authentic basal cell carcinoma. In contrast, several examples of primitive follicular induction and of trichoblastomas were seen. Other cutaneous hamartomas, hyperplasias, and neoplasms found in our series of nevus sebaceus of Jadassohn included syringocystadenoma papilliferum, sebomatricoma, apocrine gland cyst, poroma, different histopathologic variants of warts (classic warts, tricholemmoma, and desmoplastic tricholemmoma), primitive follicular induction, and ductal induction. In our series, no examples of malignant neoplasms were identified. On the basis of these findings, the classically recommended treatment for this hamartoma, which consists of early excision to prevent the development of malignancy, seems to be inappropriate.     

Becker痣24例分析

目的 探讨Becker痣的临床特点、合并症和组织病理表现。方法 回顾性分析24例Becker痣临床和病理资料。结果 24例均为散发病例,发病年龄主要集中在10～20岁(83.33%),发病部位以躯干前部和肩胛部居多(45.83%),典型皮损为较大的单侧分布的多毛的色素沉着斑,组织病理主要表现是表皮不同程度角化过度和棘层肥厚,表皮突较规则地向下延伸,基底层黑素颗粒增多,真皮网状层常见较大的形态不规则的平滑肌纤维束,伴有并发症共5例(20.83%)。结论 根据Becker痣典型皮损特点结合组织病理表现临床可以确诊,但是做为一种遗传相关的错构瘤可伴发其他皮肤肌肉骨骼异常,需仔细探明。     

Hair follicle nevus.

We present a case of hair follicle nevus, a rare hamartoma composed of vellus hair follicles. Hair follicle nevus should be differentiated from accessory auricle, trichofolliculoma and hair nevus.     

Three different clinical faces of the same histopathological entity: hair follicle nevus,trichofolliculoma and accessory tragus

BACKGROUND

Hair follicle nevus is a rare, congenital hamartoma with follicular differentiation characterized histologically by numerous, tiny, mature hair follicles. Trichofolliculoma, the histopathological features of which are quite similar to those of hair follicle nevus, is also a hamartoma that differs from hair follicle. Accessory tragus is a relatively common, benign congenital abnormality of the external ear with an incidence rate of 1 to 10 per 1,000 live births.

OBJECTIVE

This study seeks to assess the discriminatory value of currently available, histological criteria in the differential diagnosis of hair follicle nevus, accessory tragi and trichofolliculoma.

METHODS

Twenty-one patients comprising 9 cases of hair follicle nevus, 8 accessory tragi patients and 4 trichofolliculoma cases, were recruited to perform the study.

RESULTS

There were 10 males and 11 females in the study group. No significant difference was observed between the three study groups in terms of age, gender or histopathological parameters such as density of hair follicles, subcutaneous fat score and presence of connective tissue framework. Cartilaginous component was seen in 8 cases that were diagnosed as accessory tragi, while central cyst and radiating hair follicles were seen in 4 cases which were diagnosed as trichofolliculoma.

CONCLUSION

The results of our study showed that diagnostic discrimination of these diseases could be made only with the clinicopathologic correlation because of their clinical and histopathological similarities.     

Becker nevus syndrome

Becker nevus is a hyperpigmented hamartoma with an irregular outline and often hairy. It is normally found on the shoulders and chest, although it can appear in other areas. Becker nevus is sometimes associated with other muscular, skeletal, or cutaneous abnormalities such as ipsilateral breast hypoplasia or scoliosis. This characteristic phenotype of Becker nevus associated with unilateral breast hypoplasia or other abnormalities is referred to as Becker nevus syndrome. Although the lesions usually become apparent during adolescence, they are present from birth and represent part of the spectrum of so-called epidermal nevus syndromes. We present 4 cases of Becker nevus syndrome in which Becker nevus was associated with ipsilateral breast hypoplasia and, less consistently, other abnormalities.     

Nevus comedonicus

The nevus comedonicus (NC) is an uncommon variant of adnexal hamartoma which appears clinically as linear groups of open comedones. Its name may be a misnomer since, according to some, true comedones are not present. NC usually occurs by itself but may be linked with a variety of systemic findings such as skeletal or ocular anomalies. Although the nevus comedonicus is viewed by many as a hamartoma arising from a defective mesoderm, others consider this lesion to be an epidermal nevus involving the hair follicle or an appendageal nevus of sweat ducts.     

A Case of Basaloid Follicular Hamartoma

Basaloid follicular hamartoma (BFH), uncommon rare benign neoplasm connected to the adnexal structures, presents with multiple clinical manifestations that can develop into basal cell carcinoma. BFH may be congenital or acquired, and the congenital form can be further divided into the generalized and unilateral type, and the acquired form may present as localized and solitary lesions. Congenital, generalized BFH is associated with systemic diseases such as alopecia, cystic fibrosis, hypohidrosis, and myasthenia gravis. In contrast, sporadic cases are observed as unilateral or localized lesions. BFH shows thick cords and thin strands of anastomosing basaloid proliferations that arise from hair follicles and are enclosed by loose fibrous stroma. Here, we report a 70-year-old man with an acquired, solitary form of BFH.     

Circumscribed pilary dysembryoplasia of the palms

The published 9th case of circumscribed pilary dysembryoplasia of the palms is presented. Differences between this case and Becker's pigmented hair nevus, congenital smooth muscle hamartoma, circumscribed acquired hypertrichosis and pigmented nevus are discussed.     

Linear unilateral basal cell nevus with comedo-like lesions

A 20-year-old woman had linear unilateral basal cell nevus with comedo-like lesions. Numerous papules were distributed on the left side of the upper aspect of the trunk in a zosteriform fashion. The indivisual lesions were hemispherical, pearly, and waxy tumors, some of which had central plugs. Histologic examination revealed polymorphous patterns that suggested that the tumor cells differentiated toward the apocrine glands, hair structures, and sebaceous glands. Ultrastructurally, the tumor strands were composed of fairly mature basal cells with well-developed tonofilaments and desmosomes.     

Congenital non-familial unilateral basaloid follicular hamartoma

Basaloid follicular hamartoma is not a well-recognized clinical entity and has often been diagnosed as trichoepithelioma or basal cell carcinoma. It is a unique benign follicular tumour which comprises a variety of clinical manifestations. We present the case of a 24-year-old male with unilateral basaloid follicular hamartoma present at birth and later misdiagnosed as basal cell carcinoma. Histological features of basaloid follicular hamartoma are not always diagnostic and clinico-pathological correlation is particularly important to distinguish this benign hamartoma from other basaloid tumours including basal cell carcinoma. Continuous follow-up of our patient did not reveal any clinical or histological malignant transformation.     

Basal Cell Carcinoma Arising in a Nevus Sebaceus in a Child with Facial Trichoepitheliomas

Abstract: Nevus sebaceus (NS) is a congenital skin hamartoma that presents in childhood. Tumors may arise within these lesions over time. Mutations in the PTCH gene have been associated with both NS and some of the developing tumors. Only nine documented cases of basal cell carcinoma arising in nevus sebaceus in childhood are available. We present a case of an 8‐year‐old male with nevus sebaceus who developed a basal cell carcinoma. Evaluation for constitutional PTCH gene mutation and loss of heterozygosity (LOH) from the BCC within the NS did not reveal an underlying mutation. We further discuss the literature regarding prophylactic excision of NS.     

Unilateral linear basal cell nevus

Clinical, histopathological, electron-microscopical and cytophotometrical features of a case of linear unilateral basal cell nevus are reported. Several publications exist on basaliomas originating in a nevus verrucosus or nevus comedonicus. Our case, however, is regarded as an abortive form of the basal cell nevus syndrome due to somatic mutation. Only some few comparable cases are documented in the literature.     

Nestin expression in stromal cells of trichoblastoma and basal cell carcinoma

Background Both trichoblastoma and basal cell carcinoma (BCC) are considered to be a benign and malignant neoplasm of follicular germinative cells respectively. A recent investigation revealed that the mesenchymal cells in the perifollicular sheath and evolving follicular papilla of embryonic hair germs and those cells in hair follicles in early anagen express nestin. Objective The aim of the present study was to investigate whether trichoblastoma and BCC recapitulate the epithelial–mesenchymal interactions in embryonic hair germs or early anagen hair follicles by expressing nestin in stromal cells. Methods Immunohistochemical staining was performed with antibody against nestin for 15 trichoblastomas including large/small nodular, retiform and trichoepithelioma types, while adding the superficial type associated with nevus sebaceous and for 20 BCCs including superficial, nodular, nodulo‐infiltrative, and infiltrative/micronodular types. Results In all 15 trichoblastomas, the stromal cells expressed nestin with variable positive reactions, except for superficial trichoblastomas within nevus sebaceous lesions, in which stromal cells were constantly positive for nestin. In all 20 BCCs, the stromal cells were basically negative for nestin. Conclusions The development of trichoblastomas incompletely recapitulates the epithelial–mesenchymal interactions in embryonic hair germs or early anagen hair follicles, whereas BCCs fundamentally have lost this ability. Among the various types of trichoblastomas, the superficial type associated with nevus sebaceous was found to have the most similar character to either embryonic hair germs or early anagen hair follicles.     

Basal cell carcinoma appearing in a facial nevus sebaceous of Jadassohn: dermoscopic features

The nevus sebaceous of Jadassohn usually affects the face or scalp. It tends to evolve in three stages, and the final stage is characterized by the appearance of tumours. We present the case of a facial nevus sebaceous of Jadasshon in which a basal cell carcinoma developed. We also explore the diagnosis of this disease, which was established through dermoscopy, and propose using this technique in the clinical follow-up of this type of hamartoma, thereby allowing the early detection of cancer development.     

A case of localized follicular hamartoma: an ultrastructural and immunohistochemical study

We report the case of a 22-year-old woman with a nevoid plaque that we termed localized follicular hamartoma. The plaque was noticed at puberty on a unilateral site of the face and scalp. Clinically, it revealed numerous, skin-colored to light brown papules alone and in groups, occasionally bearing a single hair. Histologically, branched epithelial nests of squamoid and/or basaloid cells were revealed in connection with the interfollicular epidermis and the upper portions of hair follicles, of which the lower portions showed normal structures. Immunohistochemically, the epithelial nests showed the keratin expression consisted with that of the infundibular epithelium. S-100-positive cells were found in the epithelial nests and the stroma. Factor XIIIa-positive dendritic cells were numerous in adjacent to the epithelial nests. Ultrastructurally, immature melanocytes with a small number of premelanosomes and Merkel cells were found in the nests. Stromal dendritic cells showed the adherent features of the cytoplasmic processes to anchoring fibrils or basal lamina of the epithelial nests. From these findings, our case is a hamartoma, which seems to be an abortive growth of secondary hair germs with a limited differentiation to the upper follicular portion.     

Smooth muscle hamartoma associated with a congenital pattern melanocytic nevus, a case report and review of the literature

Smooth muscle hamartoma (SMH) is a rare benign congenital or acquired lesion sometimes associated with Becker's nevus (Becker's melanosis). We report an unusual lesion with combined features of SMH and melanocytic nevus. The patient is a 49-year-old male with a history of a changing 'mole' on the left upper back. Clinical examination showed a solitary 1.2-cm nodule with central gray pigmentation. Histological examination showed a relatively well-circumscribed intradermal lesion. The superficial portion of the lesion consisted of melanocytes with nevoid morphology. The melanocytes had congenital pattern of distribution. Lesional melanocytes acquired a spindled morphology in the deeper dermis. The base of the lesion consisted of intersecting smooth muscle fascicles focally admixed with spindled melanocytes. The melanocytic component strongly expressed melanoma antigen recognized by T-cells-1 (MART-1) and HMB-45. The smooth muscle component was strongly positive for smooth muscle actin and h-caldesmon. Neither components showed significant cytological atypia or mitotic activity. Unlike a recently reported case of SMH combined with a melanocytic nevus and basal cell carcinoma, the current lesion did not occur in association with a Becker's nevus.     

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.