Familial basaloid follicular hamartoma: lesional characterization and review of the literature

Unusual Variants of Teratoma Involving the Gynecologic Tract

Teratomas are tumors of germ cell origin, and in the female genital tract are subclassified as immature or mature based on the presence or absence, respectively, of immature elements. Somatic tumors may also develop in association with teratomas, and most commonly include thyroid tumors, carcinoids and carcinomas. We report herein 2 rare forms of gynecologic teratomas: 1 case of immature teratoma of the uterus and 1 case of a benign follicular hamartoma arising in association with mature cystic teratoma of the ovary.

"Kissing" basaloid follicular hamartomas of the eyelid

Basaloid follicular hamartomas (BFH) are rare, benign, cutaneous adnexal tumors characterized by branching cords and anastomosing strands of basaloid cells in a loose, fibrous stroma. BFH exhibit variable clinical presentations although they are commonly observed as skin to flesh colored papules and are diagnosed based on histological features. Common systemic diseases associated with BFH include alopecia, myasthenia gravis, and palmoplantar pitting. BFH of the eyelid is extremely rare with only five cases reported in the literature to date. Congenital "kissing" lesions have only previously been reported with nevi. Here we present a novel case of congenital "kissing" basaloid follicular hamartoma of the right upper and right lower eyelid and histological examination revealed intradermal nodules of basaloid cells forming reticulated strands, pseudohorn cysts, mucinous stroma and palisading with CD34 and Bcl-2 expression in the stromal fibroblasts and periphery, respectively. This article is protected by copyright. All rights reserved.

Basaloid Follicular Hamartoma: An Additional Criterion of Nevoid Basal Cell Carcinoma Syndrome

ABSTRACT

Basaloid follicular hamartoma (BFH) is a rare, benign follicular neoplasm which typically presents as brown to skin-colored papules on the face, scalp, and trunk. Histologically, BFH consists of cords and strands of basaloid cells forming cystic structures with scant stroma and should be distinguished from infundibulocystic basal cell carcinoma to avoid overly aggressive treatment. Although BFH has been found to be associated with distinct syndromes, including alopecia, myasthenia gravis, and cystic fibrosis, there is often clinical, histopathologic, and genetic overlap with nevoid basal cell carcinoma syndrome (NBCCS). In this article, we describe a case of a 13-year-old patient with NBCCS who presented with multiple BFHs and propose that it its inclusion into the diagnostic criteria for NBCCS be considered.

[Histopathological study of basaloid follicular hamartoma]

INTRODUCTION

Basaloid follicular hamartoma (BFH) is a rare tumor first described in 1985. It bears clinical and histologic similarities with basal cell carcinoma (BCC), in particular the so-called infundibulocystic form. We performed a single-center clinicopathological study of a series of typical cases of this entity that is occasionally difficult to diagnose.

MATERIALS AND METHODS

All cases of BFH seen at the Dermatopathology Laboratory of Strasbourg University Hospital were included and analyzed by means of HE staining and Ber-EP4 and PHLDA1 immunolabelling. Diagnosis was made in the event of basaloid proliferation with anastomosing cords developed from a hair follicle. Clinical data were collected from clinical files.

RESULTS

We identified 15 cases in 13 patients of mean age 44.8 years (range: 4 to 90) and the sex-ratio was 5/8. Lesions consisted of flesh-colored papules measuring 0.3 to 1.2cm in diameter, without any preferential site. Three patients had multiple lesions consisting of several coalescent papules on a breast for one, sparse papules on the back for another, and hundreds of linear unilateral BFHs, associated with osseous abnormalities, characteristic of Happle-Tinschert syndrome, for the third. All tumors were limited to the superficial and mid dermis, with a vertical orientation and connection to the epidermis in 14 of the 15 patients. In some cases, the outermost cells were basophilic while the central cells were eosinophilic. Peripheral palisading and clefting were frequently observed. Keratin cysts or sebaceous ducts were consistently present, indicating follicular differentiation. Ber-EP4+ cells were restricted to the periphery of the cords and PHLDA1 was weakly expressed.

DISCUSSION

BFH is a rare entity that must be differentiated from BCC. It presents as solitary or multiple lesions, either grouped in plaques or with a generalized or linear unilateral distribution. Generalized BFH may be associated with autoimmune diseases and linear unilateral BFH with osseous, dental and cerebral abnormalities in Happle-Tinschert syndrome. It is important to distinguish BFH from BCC to avoid inappropriate aggressive treatment.

Linear Unilateral Basaloid Follicular Hamartoma Following Blaschko's Lines: Two Case Reports and Review of the Literature

Basaloid follicular hamartoma (BFH) is a rare follicular malformation characterized by variable clinical presentations and identical histopathologic features. We present the cases of a 3-month-old boy and an 8-year-old boy with linear unilateral BFH. To the best of our knowledge, only 14 cases of linear unilateral BFH have been described in the English-language literature.

Basal cell carcinoma - molecular biology and potential new therapies

Basal cell carcinoma (BCC) of the skin, the most common malignancy in individuals of mixed European descent, is increasing in incidence due to an aging population and sun exposure habits. The realization that aberrant activation of Hedgehog signaling is a pathognomonic feature of BCC development has opened the way for exciting progress toward understanding BCC biology and translation of this knowledge to the clinic. Genetic mouse models closely mimicking human BCCs have provided answers about the tumor cell of origin, and inhibition of Hedgehog signaling is emerging as a potentially useful targeted therapy for patients with advanced or multiple BCCs that have hitherto lacked effective treatment.

Basal cell carcinomas in mice arise from hair follicle stem cells and multiple epithelial progenitor populations

Uncontrolled Hedgehog (Hh) signaling leads to the development of basal cell carcinoma (BCC), the most common human cancer, but the cell of origin for BCC is unclear. While Hh pathway dysregulation is common to essentially all BCCs, there exist multiple histological subtypes, including superficial and nodular variants, raising the possibility that morphologically distinct BCCs may arise from different cellular compartments in skin. Here we have shown that induction of a major mediator of Hh signaling, GLI2 activator (GLI2ΔN), selectively in stem cells of resting hair follicles in mice, induced nodular BCC development from a small subset of cells in the lower bulge and secondary hair germ compartments. Tumorigenesis was markedly accelerated when GLI2ΔN was induced in growing hair follicles. In contrast, induction of GLI2ΔN in epidermis led to the formation of superficial BCCs. Expression of GLI2ΔN at reduced levels in mice yielded lesions resembling basaloid follicular hamartomas, which have previously been linked to low-level Hh signaling in both mice and humans. Our data show that the cell of origin, tissue context (quiescent versus growing hair follicles), and level of oncogenic signaling can determine the phenotype of Hh/Gli-driven skin tumors, with high-level signaling required for development of superficial BCC-like tumors from interfollicular epidermis and nodular BCC-like tumors from hair follicle stem cells.

Keratin 17 promotes epithelial proliferation and tumor growth by polarizing the immune response in skin

Basaloid skin tumors, including basal cell carcinoma (BCC) and basaloid follicular hamartoma (BFH), are associated with aberrant Hedgehog (Hh) signaling1 and, in the case of BCC, an expanding set of genetic variants including keratin 5 (K5)2, an intermediate filament-forming protein. We show that genetic ablation of keratin 17 (K17) protein, which is induced in basaloid skin tumors3,4 and co-polymerizes with K5 in vivo5, delays BFH tumor initiation and growth in mice with constitutive Hh signaling in epidermis6,7. The delay is preceded by reduced inflammation and a polarization of inflammatory cytokines from a Th1/Th17- to a Th2-dominated profile. Absence of K17 also attenuates hyperplasia and inflammation in a model of acute dermatitis. Re-expression of K17 in Gli2^tg K17^−/− keratinocytes induces select Th1 chemokines with established roles in BCC. Our findings establish a novel immunomodulatory role for K17 in Hh-driven basaloid skin tumors that could impact additional tumor settings, psoriasis, and wound repair.

Basaloid follicular hamartoma

Basaloid follicular hamartoma is a benign lesion of important consideration because it can be mistaken both clinically and histologically for basal cell carcinoma. The formation of basaloid follicular hamartoma has been linked to a mutation in the patched gene, which is part of the same pathway implicated in nevoid basal cell carcinoma syndrome. While these hamartomas are considered benign lesions, malignant growths have been reported to arise within them, which raises the question, "Is basaloid follicular hamartoma a premalignant lesion?" Correct identification allows for periodic monitoring for malignant transformation, while sparing patients unnecessary surgery. Treatment strategies, including experimental therapies, are reviewed.

Infundibulocystic basal cell carcinoma of the eyelid in basal cell nevus syndrome

PURPOSE

To describe the histopathologic findings in a series of eyelid basal cell carcinomas removed from patients with basal cell nevus syndrome.

METHODS

Retrospective case series of 5 patients with basal cell nevus syndrome identified from our oculoplastics service. The systemic and ophthalmic features were reviewed, and a retrospective histopathologic analysis of all available previously excised eyelid lesions was performed. The pertinent published literature on basal cell nevus syndrome and eyelid basal cell carcinoma was reviewed.

RESULTS

A total of 26 eyelid lesions were examined histopathologically. Twenty-three of these lesions were basal cell carcinomas. The infundibulocystic variant of basal cell carcinoma was identified most commonly (57%).

CONCLUSIONS

Eyelid basal cell carcinomas in patients with basal cell nevus syndrome were commonly of the infundibulocystic variety in our series. Infundibulocystic basal cell carcinomas, which can be clinically indistinguishable from the more common forms, are thought to be less aggressive than other types of basal cell carcinoma and are a reassuring histopathologic diagnosis. It is important for the ophthalmologist and pathologist to be aware of infundibulocystic basal cell carcinomas, as they are more common in patients with basal cell nevus syndrome and may be a clue to the diagnosis of this autosomal dominant cancer-predisposition syndrome or other associated syndromes. To our knowledge, this variant of basal cell carcinoma has not been previously discussed in the ophthalmic literature.

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.

Decreased Srcasm expression in hyperproliferative cutaneous lesions

BACKGROUND

Src-family tyrosine kinases (SFKs) are signaling proteins that regulate keratinocyte proliferation and differentiation. Src-activating and signaling molecule (Srcasm) is a recently identified molecule that downregulates SFK activity and promotes keratinocyte differentiation. To determine if Srcasm expression correlates with keratinocyte differentiation, we characterized the level of Srcasm expression in some cutaneous lesions that exhibit increased keratinocyte proliferation.

METHODS

Formalin-fixed sections of randomly selected seborrheic keratoses (SKs) and basal cell carcinomas (BCCs) were analyzed for Srcasm and Ki-67 immunohistochemical staining. Anti-Srcasm and anti-Ki-67 stainings were performed in parallel.

RESULTS

All SKs displayed decreased Srcasm staining in areas comprised of basaloid keratinocytes that exhibited an increased Ki-67 index. Higher Srcasm staining levels were detected near pseudohorn cysts where keratinocytes exhibited a lower Ki-67 index. All multicentric and nodular BCCs displayed a prominent loss of Srcasm staining in association with a marked increase in Ki-67 staining.

CONCLUSIONS

Our results support the hypothesis that Srcasm protein levels are decreased in the hyperproliferative keratinocytes found in SKs and BCCs. Increased Srcasm protein levels are detected in keratinocytes undergoing differentiation. Decreased Srcasm levels may be part of the pathophysiologic mechanism in cutaneous lesions, exhibiting keratinocyte hyperproliferation.

Pathological responses to oncogenic Hedgehog signaling in skin are dependent on canonical Wnt/beta3-catenin signaling

Constitutive Hedgehog (Hh) signaling underlies several human tumors, including basal cell carcinoma (BCC) and basaloid follicular hamartoma in skin. Intriguingly, superficial BCCs arise as de novo epithelial buds resembling embryonic hair germs, collections of epidermal cells whose development is regulated by canonical Wnt/beta-catenin signaling. Similar to embryonic hair germs, human BCC buds showed increased levels of cytoplasmic and nuclear beta-catenin and expressed early hair follicle lineage markers. We also detected canonical Wnt/ beta-catenin signaling in epithelial buds and hamartomas from mice expressing an oncogene, M2SMO, leading to constitutive Hh signaling in skin. Conditional overexpression of the Wnt pathway antagonist Dkk1 in M2SMO-expressing mice potently inhibited epithelial bud and hamartoma development without affecting Hh signaling. Our findings uncover a hitherto unknown requirement for ligand-driven, canonical Wnt/ beta-catenin signaling for Hh pathway-driven tumorigenesis, identify a new pharmacological target for these neoplasms and establish the molecular basis for the well-known similarity between early superficial BCCs and embryonic hair germs.

Two Cases of Nevoid Basal Cell CarcinomaSyndrome in One Family

The nevoid basal cell carcinoma syndrome, or Gorlin-Goltz syndrome, is an autosomal dominant multiple system disorder with high penetrance and variable expressions, although it can also arise spontaneously. The diagnostic criteria for nevoid basal cell carcinoma syndrome include multiple basal cell carcinomas, palmoplantar pits, multiple odontogenic keratocysts, skeletal anomalies, positive family history, ectopic calcification and neurological anomalies. We report a brother and sister who were both diagnosed with nevoid basal cell carcinoma syndrome.

Bcl-2, CD34 and CD10 expression in basaloid follicular hamartoma, vellus hair hamartoma and neurofollicular hamartoma demonstrate full follicular differentiation

Generalized basaloid follicular hamartoma syndrome (GBFHS) is a rare, recently-described, autosomal-dominantly inherited disorder that presents with disseminated milia, palmoplantar pitting, hypotrichosis and basaloid follicular hamartomas (BFH). BFH is a benign adnexal tumor that resembles basal cell carcinoma (BCC). In this study, we report two cases of GBFHS and stain BFH, a vellus hair hamartoma (VHH) and a neurofollicular hamartoma (NH) with CD34, bcl-2 and CD10 to characterize and compare the staining patterns of these follicular tumors. Standard immunohistochemistry labeling with CD34, bcl-2 and CD10 was performed on paraffin-embedded, formalin-fixed tissue sections of five BFH (four for CD10), one VHH and one NH. CD34 stromal staining was observed in all specimens. Bcl-2 stained the outermost cell layers of the basaloid nests in all specimens. CD10 stained the peritumoral stroma of all specimens. The BFH, NFH and the VHH showed CD10 staining of matrical cells. CD34 and CD10 stain peritumoral stroma of BFH, VHH and NH. Bcl-2 stains the outermost cell layer of these tumors. CD10 was also observed to stain matrical cells. These results show the similarities in differentiation between these benign follicular neoplasms and trichoepithelioma.

Skin adnexal neoplasms--part 1: an approach to tumours of the pilosebaceous unit

Skin adnexal neoplasms comprise a wide spectrum of benign and malignant tumours that exhibit morphological differentiation towards one or more types of adnexal structures found in normal skin. Most adnexal neoplasms are relatively uncommonly encountered in routine practice, and pathologists can recognise a limited number of frequently encountered tumours. In this review, the first of two, the normal histology of the skin adnexal structures is reviewed, and the histological features of selected but important benign and malignant tumours and tumour-like lesions of pilosebaceous origin discussed, with emphasis on the diagnostic approach and pitfalls in histological diagnosis.

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.

Genetics of skin appendage neoplasms and related syndromes

In the past decade the molecular basis of many inherited syndromes has been unravelled. This article reviews the clinical and genetic aspects of inherited syndromes that are characterised by skin appendage neoplasms, including Cowden syndrome, Birt-Hogg-Dube syndrome, naevoid basal cell carcinoma syndrome, generalised basaloid follicular hamartoma syndrome, Bazex syndrome, Brooke-Spiegler syndrome, familial cylindromatosis, multiple familial trichoepitheliomas, and Muir-Torre syndrome.

Clinical Application of Dynamic Telepathology in Mohs Surgery

BACKGROUND

Telepathology is an expanding technology in multiple fields for remote pathology diagnosis and consultation. The use of telepathology in Mohs surgery has been very limited.

OBJECTIVE

To describe the clinical experience of using a telepathology system for intraoperative consultations on difficult frozen sections during Mohs surgery.

MATERIALS AND METHODS

Intraoperative consultation with a dermatopathologist was obtained using a dynamic telepathology system for all questions arising on frozen sections during Mohs surgery for nonmelanoma skin cancers during a 2-year period.

RESULTS

The most common reason for consultation was to distinguish basal cell carcinoma from a benign histologic simulant on Mohs frozen sections. Other uses included determining tumor histology and distinguishing inflammation from residual tumor.

CONCLUSION

Dynamic telepathology is a useful and convenient adjunct in the Mohs surgery practice for intraoperative consultations on difficult frozen sections.

Linear basaloid follicular hamartoma on the Blaschko's line of the face

We report a 5-year-old girl with localized basaloid follicular hamartoma. The lesion consisted of a linear, hypopigmented, atrophic patch on the right lateral side of nose. Of great interest is that the linear distribution of lesion may follow the Blaschko's line of the face.

Nevoid basal cell carcinoma syndrome or multiple hereditary infundibulocystic basal cell carcinoma syndrome?

We present a case of nevoid basal cell carcinoma syndrome, also known as Gorlin syndrome, or basal cell nevus syndrome, which clinically follows a course more consistent with multiple hereditary infundibulocystic basal cell carcinomas or multiple hereditary trichoepitheliomas. The following article describes the case in detail and gives an overview of other genodermatosis, which were initially considered in the differential and which may be linked pathogenetically.

Temporal stability of insular avian malarial parasite communities

Avian malaria is caused by a diverse community of genetically differentiated parasites of the genera Plasmodium and Haemoproteus. Rapid seasonal and annual antigenic allele turnover resulting from selection by host immune systems, as observed in some parasite populations infecting humans, may extend analogously to dynamic species compositions within communities of avian malarial parasites. To address this issue, we examined the stability of avian malarial parasite lineages across multiple time-scales within two insular host communities. Parasite communities in Puerto Rico and St Lucia included 20 and 14 genetically distinct parasite lineages, respectively. Lineage composition of the parasite community in Puerto Rico did not vary seasonally or over a 1 year interval. However, over intervals approaching a decade, the avian communities of both islands experienced an apparent loss or gain of one malarial parasite lineage, indicating the potential for relatively frequent lineage turnover. Patterns of temporal variation of parasite lineages in this study suggest periodic colonization and extinction events driven by a combination of host-specific immune responses, competition between lineages and drift. However, the occasional and ecologically dynamic lineage turnover exhibited by insular avian parasite communities is not as rapid as antigenic allele turnover within populations of human malaria.