Segmental basaloid follicular hamartomas derive from a post-zygotic SMO p.L412F pathogenic variant and express hair follicle development-related proteins in a pattern that distinguish them from basal cell carcinomas.

Basaloid follicular hamartomas (BFH) are benign small basaloid skin tumors that can present as solitary or multiple lesions. Congenital BFH lesions arranged in a segmental distribution have been described, suggesting they derive from a somatic post-zygotic mutational event. Previously, BFH were described in Happle-Tinschert syndrome, which results from a post-zygotic SMO variant and is characterized by segmental BFH with variable involvement of the teeth, skeleton, and central nervous system. Here, we describe two patients with isolated segmental BFH and no systemic involvement. Paired whole exome sequencing of BFH and normal tissue revealed a pathogenic SMO c.1234 C>T, p.L412F variant restricted to BFH tissue. We characterized the proliferation index and expression of Hedgehog and Wnt/beta-catenin pathway related proteins in segmental BFH compared to sporadic basal cell carcinomas (BCCs) and found that segmental BFH had a lower proliferation index. Although segmental BFH expressed a similar level of Gli-1 compared to BCCs, levels of LEF-1 and SOX-9 expression in BFH were weaker for both and patchier for LEF-1. Our results show that a somatic SMO activating variant causes segmental BFH. Since these patients are prone to developing BCCs, differences in SOX9, LEF1, and Ki-67 expression can help distinguish between these two basaloid lesions.

Identification of a recurrent nonsense mutation in HR gene responsible for atrichia with papular lesions in two Kashmiri families.

BACKGROUND: Congenital atrichia (CA) is a rare form of irreversible alopecia with an autosomal recessive mode of inheritance. This form of hair loss is mainly associated with mutations in the human hairless (HR) gene located at chromosome 8p21.3. An additional unique feature atrichia with papular lesions (APL) comprises keratin-filled cysts known as papules. The present study aimed to uncover the underlying genetic causes of APL in two consanguineous Kashmiri families. METHODS: In the present study, two consanguineous families of Kashmiri origin with APL displaying an autosomal recessive mode of inheritance were investigated. Whole exome and Sanger sequencing followed by bioinformatic studies, variant prioritization, Sanger validation and segregation analysis was performed to find the mutation. RESULTS: A recurrent nonsense (NM_005144: c.2818C > T:p.Arg940*) mutation was detected in exon 13 of the human HR gene. CONCLUSIONS: Whole exome sequencing analysis has widely been used in the screening of single gene disorders mutations, both in research and diagnostic laboratories. Sanger sequencing alone for genes such as HR becomes expensive and time consuming. Instead, it is recommended that a patient is to screen by whole exome sequencing and then special attention first focuses on known genes of the APL phenotype. This is helpful for intime diagnosis, being more efficient and economic. The results obtained in the present study may contribute to prenatal diagnosis, carrier secreening and the genetic counseling of families with the APL phenotype in Kashmiri poplution.

Apparent darkening of scalp hair related to pili multigemini Following dabrafenib and trametinib.

The combination of dabrafenib and trametinib is an important immunotherapy option for patients with BRAF V600 mutation-positive melanoma. This regimen has been reported to cause cutaneous eruptions. However, hair dysmorphology is not a reported side effect to these or any other medications to date. Herein, we highlight a case of pili multigemini formation in a patient with stage IV melanoma receiving treatment with dabrafenib and trametinib and the corresponding clinical findings.

Congenital atrichia with papular lesions.

Congenital atrichia with papular lesions is a rare, autosomal recessive and irreversible form of total alopecia of the body hair characterized by hair loss soon after birth and the development of keratinfilled cysts or horny papules over extensive areas of the body. The condition is associated with a mutation of the human hairless gene on chromosome region 8p12. We report a 1-year-old boy presenting with the absence of scalp and body hair since birth. On examination, he had complete absence of hair on the scalp, eyebrows, and eyelashes. Multiple, discrete, pearly-to-skin-colored papules of 1-3mm in size were present over the scalp. The skin biopsy from a scalp papule revealed normal overlying epidermis with multiple keratin cysts and hypoplastic hair follicles in the upper dermis.

Human Hairless Protein Roles in Skin/Hair and Emerging Connections to Brain and Other Cancers.

The mammalian hairless protein (HR) is a 130 kDa nuclear transcription factor that is essential for proper skin and hair follicle function. Previous studies have focused on the role of HR in skin maintenance and hair cycling. However, the hairless gene (HR) is also expressed in brain and other tissues, where its role remains poorly understood. HR has been reported to contain functional domains that potentially serve in DNA binding, histone demethylation, nuclear translocation and protein-protein interactions. Indeed, HR has been shown to interact with and repress the action of the nuclear receptors for vitamin D and thyroid hormone as well as RAR-related orphan receptor alpha, possibly via recruitment of histone deacetylases. HR may also have important functions in non-skin tissues given that nearly 200 HR mutations have been identified in patients with various cancers, including prostate, breast, lung, melanoma, uterine, and glioma. This suggests that HR and/or mutants thereof have relevance to the growth and survival of cancer cells. For example, the reported intrinsic histone H3K9 demethylase activity of HR may activate dormant genes to contribute to carcinogenesis. Alternatively, the demonstrated ability of HR to interact with p53 and/or the p53 DNA response element to influence p53-regulated pathways may explain, at least in part, why many cancers express mutated HR proteins. In this review, we summarize the current knowledge of HR bioactions, how HR mutations may be contributing to alopecia as well as to cancer, and, finally, outline future directions in the study of this largely enigmatic nuclear protein. J. Cell. Biochem. 119: 69-80, 2018. © 2017 Wiley Periodicals, Inc.

Generalized basaloid follicular hamartoma syndrome versus Gorlin syndrome: A diagnostic challenge.

Basaloid follicular hamartoma is a relatively rare benign neoplasm of follicular origin that can be mistaken histologically for basal cell carcinoma, but hereditary forms of basaloid follicular hamartoma are associated with nevoid basal cell carcinoma syndrome, or Gorlin syndrome. The pathophysiology of basaloid follicular hamartoma development involves mutations in the patched gene, which is also causative in nevoid basal cell carcinoma syndrome. We present a mother and daughter with basaloid follicular hamartomas, with genetic testing confirming patched gene mutation in the daughter.

Alkaline ceramidase 1 is essential for mammalian skin homeostasis and regulating whole-body energy expenditure.

The epidermis is the outermost layer of skin that acts as a barrier to protect the body from the external environment and to control water and heat loss. This barrier function is established through the multistage differentiation of keratinocytes and the presence of bioactive sphingolipids such as ceramides, the levels of which are tightly regulated by a balance of ceramide synthase and ceramidase activities. Here we reveal the essential role of alkaline ceramidase 1 (Acer1) in the skin. Acer1-deficient (Acer1(-/-) ) mice showed elevated levels of ceramide in the skin, aberrant hair shaft cuticle formation and cyclic alopecia. We demonstrate that Acer1 is specifically expressed in differentiated interfollicular epidermis, infundibulum and sebaceous glands and consequently Acer1(-/-) mice have significant alterations in infundibulum and sebaceous gland architecture. Acer1(-/-) skin also shows perturbed hair follicle stem cell compartments. These alterations result in Acer1(-/-) mice showing increased transepidermal water loss and a hypermetabolism phenotype with associated reduction of fat content with age. We conclude that Acer1 is indispensable for mammalian skin homeostasis and whole-body energy homeostasis. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

To grow or not to grow: hair morphogenesis and human genetic hair disorders.

Mouse models have greatly helped in elucidating the molecular mechanisms involved in hair formation and regeneration. Recent publications have reviewed the genes involved in mouse hair development based on the phenotype of transgenic, knockout and mutant animal models. While much of this information has been instrumental in determining molecular aspects of human hair development and cycling, mice exhibit a specific pattern of hair morphogenesis and hair distribution throughout the body that cannot be directly correlated to human hair. In this mini-review, we discuss specific aspects of human hair follicle development and present an up-to-date summary of human genetic disorders associated with abnormalities in hair follicle morphogenesis, structure or regeneration.

Hair follicle morphogenesis and epidermal homeostasis in we/we wal/wal mice with postnatal alopecia.

Mice with skin and hair follicle (HF) defects are common models of human skin disorders. A mutant strain with the we/we wal/wal genotype develops alopecia. We found the hair shaft structure in the pelage of mutant mice to have significant defects. Although these mice lose their hair at 21 days, a label-retaining cell population persists in HFs until at least day 54. Depilation-induced anagen was accomplished in we/we wal/wal mutants but the resulting hair shafts were short and extremely deformed. Serious abnormalities in epidermis stratification and HF morphogenesis exist in we/we wal/wal homozygous E18.5 embryos. There were significantly fewer HF primordia in this mutant compared with wild type. We discovered specific structures, identified as invalid placodes, positive for ectodysplasin A1 receptor, nuclear ß-catenin, and LEF1, which failed to invaginate, produced a double basal-like layer of epidermal cells, and lacked cylindrical keratinocytes. Specification of dermal papillae (DP) was impaired, and the papillary dermis expressed alkaline phosphatase and LEF1. We also detected DP-like groups of intensively stained cells in the absence of visible signs of folliculogenesis in the epidermis. We showed differentiation disturbances in the mutant embryonic E18.5 epidermis and HFs: The cornified layer was absent, the width of the spinous layer was reduced, and HFs lacked LEF1-positive precortex cells. In this study, we used a very interesting and useful mouse model of alopecia. The presence of symptoms of skin disorders in we/we wal/wal murine embryos correlates with the postnatal skin phenotype. This correlation may help to evaluate reasons of alopecia.

Clinical, dermoscopic, and histopathologic features of body hair disorders.

Dermoscopic examination of hair and scalp, also named "trichoscopy," is an essential tool in diagnosis of hair and scalp diseases. Trichoscopy is fast and noninvasive and can be used to evaluate hair disorders in all body areas. Body hair disorders are uncommon, and most publications on their dermoscopic features are limited to case reports or series. In this review we present the available information on the dermoscopic diagnosis of body hair disorders including keratosis pilaris, trichostasis spinulosa, pili multigemini, circle hairs, rolled hairs, eruptive vellus hair cyst, and ingrown hairs.

Generalized basaloid follicular hamartoma syndrome: a case report and review of the literature.

Basaloid follicular hamartoma (BFH) is a rare, generally benign lesion of importance because of its clinical and histopathological similarity to infundibulocystic basal cell carcinoma. Autosomal dominant generalized BFH syndrome is 1 of the 5 clinical forms of BFH that has been described in the literature. We report a case of BFH syndrome in a 47-year-old Hispanic female who presented with an increasing number of small 1- to 2-mm tan to brown smooth facial papules, few palmar pits, and cobblestoning of the tongue. Her mother had similar lesions on her face. A biopsy of one of the patient's facial lesions confirmed the diagnosis of BFH. Of note, this patient later presented with rapid growth of one of her facial lesions, and a subsequent biopsy confirmed the development of a basal cell carcinoma arising within one of her BFH lesions. Although BFH is classically stable for years and does not require immediate surgical removal, our case highlights the importance of continual monitoring of these patients, given the potential for malignant transformation of these lesions.

Scanning Electron Microscopic Hair Shaft Analysis in Ectodermal Dysplasia Syndromes.

OBJECTIVES: The objective of the current study was to catalog hair shaft abnormalities in individuals with ectodermal dysplasia (ED) syndromes using scanning electron microscopy (SEM) and to compare the findings with those in unaffected controls. This is the second of a two-part study, the first of which used light microscopy as the modality and was previously published. METHODS: Scanning electron microscopy was performed in a blinded manner on hair shafts from 65 subjects with seven types of ED syndromes and 41 unaffected control subjects. Assessment was performed along the length of the shaft and in cross section. SETTING: Hair donations were collected at the 28th Annual National Family Conference held by the National Foundation for Ectodermal Dysplasia. Control subjects were recruited from a private dermatology practice and an academic children's hospital outpatient dermatology clinic. RESULTS: SEM identified various pathologic hair shaft abnormalities in each type of ED and in control patients. When hairs with all types of ED were grouped together and compared with those of control patients, the difference in the presence of small diameter and shallow and deep grooves was statistically significant (p < 0.05). When the EDs were separated according to subtype, statistically significant findings were also seen. CONCLUSION: SEM is a possible adjuvant tool in the diagnosis of ED syndromes. There are significant differences, with high specificity, between the hairs of individuals with ED and those of control subjects and between subtypes.

Cytokeratin 20 expression in basaloid follicular hamartoma and infundibulocystic basal cell carcinoma.

BACKGROUND: Tumors with similar or identical histopathologic features have been termed basaloid follicular hamartoma (BFH) or infundibulocystic basal cell carcinoma (BCC). BCC typically lacks immunoreactivity with cytokeratin 20 (CK20) and pleckstrin homology-like domain, family A, member 1 protein (PHLDA1). AIM: A series of BFH and infundibulocystic BCC were investigated to determine the pattern of CK20 and PHLDA1 labeling in these lesions. MATERIALS AND METHODS: Thirty-six samples of BFH (n = 14) and infundibulocystic BCC (n = 22) were collected. CK20 and PHLDA1 staining was performed and evaluated. RESULTS: All the lesions were small (average of 3 mm), well circumscribed, and composed of basaloid to squamoid cells arranged in islands resembling ramifying rootlets with interspersed horn cysts. CK20-positive cells were present in all 36 cases (average, 22/mm(2)), throughout the tumor, including deeper portions, irrespective of original diagnosis. Six of thirty cases (20%; 5 infundibulocystic BCC, 1 BFH) were focally PHLDA1 positive. CONCLUSIONS: Findings on hematoxylin and eosin staining and those of CK20 staining in BFH and infundibulocystic BCC were similar, and in most cases were indistinguishable. The CK20 labeling was similar to that of trichoepithelioma. The findings add a degree of support to the argument that BFH and infundibulocystic BCC represent the same lesion and, further, a benign one.

Novel compound heterozygous mutations in the desmoplakin gene cause hair shaft abnormalities and culminate in lethal cardiomyopathy.

A 2-month-old white girl born to nonconsanguineous parents presented to the dermatology department with hair loss that had commenced a few months after birth. Although her hair loss later stabilized, it remained sparse. By the age of 2 years, she was noted to have developed focal keratoderma over pressure points of the soles. Aged 5 years, she was admitted to hospital with a chest infection, and investigations at that point revealed that she had a dilated cardiomyopathy. Subsequent genetic investigations identified compound heterozygous mutations in the 3' end of the desmoplakin (DSP) gene (7567delAAGA and 6577G>A), explaining the cardiocutaneous phenotype.

Solitary Basaloid Follicular Hamartoma: A Report of Two Cases.

Basaloid follicular hamartoma (BFH) is rare benign follicular malformation that is often clinically misdiagnosed. Patients with BFH demonstrate a variety of clinical manifestations and associated abnormalities. BFH may be a familial, congenital, or acquired condition with localized or generalized distribution. Several clinical variants of generalized BFH are known, and they can be associated with a diverse spectrum of abnormalities. Herein, we report two cases of solitary BFH in pediatric patients, both documented dermoscopically.

Atrichia with papular lesions in a chinese family caused by novel compound heterozygous mutations and literature review.

BACKGROUND: Congenital atrichia with papular lesions (APL) is characterized by complete absence of body hair shortly after birth, along with papules, and caused by mutations in the hairless gene (HR). OBJECTIVE: To investigate whether APL with HR mutations might also be found among patients in non-consanguineous Chinese families and to discuss the phenotypic variations with the same mutations. METHODS: DNA sequencing of the HR was performed in the Chinese pedigree and in 100 controls. RESULTS: A nonsense mutation c.T2265A in the patient and his father as well as a 2bp deletion (3482delCT) in the patient and his mother were detected. CONCLUSION: Our study identified the first mutation in exon 10 in HR as well as the second novel compound heterozygous mutations in a Chinese family, also adding new variants to the knowledge of HR mutations in APL. Phenotypic heterogeneity in congenital atrichia might be subject to the founder genes or modifier genes.