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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.

Background: Little is known about the ultrastructure of pili annulati., Objectives: To examine with transmission electron microscopy affected hairs of a family, whose diagnosis had been confirmed in five individuals with scanning electron microscopy, which showed surface undulations with "curtain-like" folding of the hair cuticula and to compare the findings with normal control., Methods: Hairs of two affected patients and one control were embedded in resin and cut lengthwise to produce ultra-thin sections., Results: The normal hair showed a parallel arrangement of dark lines associated with less electron-dense wide bands. Small cavities could be observed, mostly in the dark lines, affected hairs had a large number of cavities, associated or not with the insertion of melanosomes and loss of parallelism of the dark lines. Higher magnification showed a significant loss of this parallelism, resembling "wood grooves". Widened dark lines were observed in some areas., Study Limitations: Only a few hairs were examined., Conclusions: The present results suggest that the microcanaliculi of the hair surface, easily found with scanning electron microscopy, may be secondary not only to the cavities seen in the sections but also to the disorder of proteins that form this region, demonstrated by the changes of the cortex dark lines., (Copyright © 2022 Sociedade Brasileira de Dermatologia. Published by Elsevier España, S.L.U. All rights reserved.)

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., (© 2020 John Wiley & Sons, Ltd.)

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.

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.

Development of the skin epidermis requires tight spatiotemporal control over the activity of several signaling pathways; however, the mechanisms that orchestrate these events remain poorly understood. Here, we identify a key role for the Wave complex proteins ABI1 and Wave2 in regulating signals that control epidermal shape and growth. In utero RNAi-mediated silencing of Abi1 or Wasf2 induced cellular hyperproliferation and defects in architecture of the interfollicular epidermis (IFE) and delayed hair follicle growth. Unexpectedly, SOX9, a hair follicle growth regulator, was aberrantly expressed throughout the IFE of the mutant embryos, and its forced overexpression mimicked the Wave complex loss-of-function phenotype. Moreover, Wnt signaling, which regulates SOX9 + cell specification, was up-regulated in Wave complex loss-of-function IFE. Importantly, we show that the Wave complex regulates filamentous actin content and that a decrease in actin levels is sufficient to elevate Wnt/β-catenin signaling. Our results identify a novel role for Wave complex- and actin-regulated signaling via Wnt and SOX9 in skin development., (© 2019 Cohen et al.)

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., (© 2018 Wiley Periodicals, Inc.)

Trichoscopy allows analyzing the structure and size of growing hair shafts in their natural environment in children and adults. The method replaces light microscopy, which requires pulling of multiple hairs for investigation. In monilethrix, trichoscopy shows uniform elliptical nodosities with intermittent constrictions. In trichorrhexis nodosa nodular thickenings along hairs shafts are visible (low magnification) or splitting into numerous small fibers along the hair shaft may be observed (high magnification). In trichorrhexis invaginata (bamboo hair) the hair shaft telescopes into itself at several points along the shaft. Trichoscopy shows small nodules along the shaft. Hairs bend and break in these diseases. Trichoscopy of pili torti shows twists of hair shafts along their long axis. In pili annulati hair shafts with alternating white and dark bands are visible. In woolly hair the examination demonstrates hair shafts with waves at very short intervals. For trichothiodystrophy polarized trichoscopy should be used. In ectodermal dysplasias, trichoscopy shows a variety of hair abnormalities, but the most characteristic finding is hair shaft pigmentation heterogeneity., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Congenital atrichia with papular lesions (APL) is a disease characterized by the complete absence of hair from the whole body occurring within a few months of birth and the presence of papules distributed over the body. A 9-year-old boy presented with sparse hair over his body and with a history of losing his hair soon after birth. Multiple skin-colored papules were observed over the scalp. A biopsy from a papule showed keratinous cysts in the dermis and the absence of hair follicles. A diagnosis of congenital APL was made after vitamin D-dependent rickets was excluded. This case highlights congenital APL as a cause of total alopecia.

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., (© 2017 Wiley Periodicals, Inc.)

Background/aim: Nevoid basal cell carcinoma syndrome (NBCCS) is an autosomal dominantly inherited disorder characterized by multiple basal cell carcinomas (BCC), odontogenic tumors and various skeletal anomalies. Basaloid follicular hamartomas (BFHs) constitute rare neoplasms that can be detected in sporadic and familial settings as in the Basaloid Follicular Hamartoma Syndrome (BFHS). Although BFHS shares clinical, histopathological and genetic overlapping with the NBCCS, they are still considered two distinctive entities. The aim of our single-institution study was the analysis of a cohort of PTCH1-mutated patients in order to define clinical and biomolecular relationship between NBCCS and BFHs., Materials and Methods: In our study we evaluated PTCH1 gene-carrier probands affected by NBCCS to detect the incidence of BFHs and their correlation with this rare syndrome., Results: Among probands we recognized 4 patients with BFHs. We found 15 germline PTCH1 mutations, uniformly distributed across the PTCH1 gene. Six of them had familial history of NBCCS, two of them were novel and have not been described previously., Conclusion: NBCCS and BFHS may be the same genetic entity and not two distinctive syndromes. The inclusion of BFH in the NBCCS cutaneous tumor spectrum might be useful for the recognition of misdiagnosed NBCCS cases that could benefit from tailored surveillance strategies., (Copyright© 2018, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.)

Background: Atrichia with papular lesions (APL) is a rare irreversible form of complete hair loss inherited in autosomal recessive manner. Hair loss is often followed by the appearance of multiple keratin-filled cysts or papules on exterior parts of the body. This phenotype results due to mutations in the human hairless gene (HR) mapped on chromosome 8p21.3. The present study was aimed to search for disease-causing sequence variants in the HR gene in five consanguineous families exhibiting features of APL., Methods: Linkage in five Pakistani lineal consanguineous families, displaying features of APL, was tested using microsatellite markers flanking the HR gene on chromosome 8p21.3. After constructing the haplotypes, variants in the gene HR were searched by dideoxy-chain termination sequencing., Results: Haplotype analysis established linkage in all five families to the HR gene located on chromosome 8p.21.3. Subsequently, sequencing HR identified a novel homozygous nonsense variant (c.2541G>A, p.Trp847*) in one and previously reported two pathogenic variants (p.Cys690*, p.Pro1157Arg) in the other four families., Conclusion: Mutations identified extend the spectrum of mutations in the HR gene resulting in APL. Characterizing the clinical spectrum resulting from the disease-causing homozygous variants in the HR gene will direct clinical care of the family members., (© 2015 The International Society of Dermatology.)

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., (© 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.)

Dominant mutations in keratin genes can cause a number of inheritable skin disorders characterized by intraepidermal blistering, epidermal hyperkeratosis, or abnormalities in skin appendages, such as nail plate dystrophy and structural defects in hair. Allele-specific silencing of mutant keratins through RNA interference is a promising therapeutic approach for suppressing the expression of mutant keratins and related phenotypes in the epidermis. However, its effectiveness on skin appendages remains to be confirmed in vivo. In this study, we developed allele-specific small interfering RNAs capable of selectively suppressing the expression of a mutant Krt75, which causes hair shaft structural defects characterized by the development of blebs along the hair shaft in mice. Hair regenerated from epidermal keratinocyte progenitor cells isolated from mutant Krt75 mouse models reproduced the blebbing phenotype when grafted in vivo. In contrast, mutant cells manipulated with a lentiviral vector expressing mutant Krt75-specific short hairpin RNA (shRNA) persistently suppressed this phenotype. The phenotypic correction was associated with a significant reduction of mutant Krt75 mRNA in the skin grafts. Thus, data obtained from this study demonstrated the feasibility of utilizing RNA interference to achieve durable correction of hair structural phenotypes through allele-specific silencing of mutant keratin genes., (Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.)

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., (© 2015 Wiley Periodicals, Inc.)

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., (Copyright © 2015 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

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 β-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.

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.

Recent developments in research methods and techniques, such as whole-exome and -genome sequencing, have substantially improved our understanding of genetic conditions. Special progress has been made in the field of genotrichoses, or hereditary hair diseases, a field that has been obscure for many years. The underlying genes for many of the monogenic hair diseases are now known. Additionally, complex analyses of large cohorts of patients have given us the first clues to the genes associated with polygenic hair disorders, such as androgenetic alopecia and alopecia areata. Thanks to these major findings, the sophisticated regulation of the morphogenesis, development and growth of hair follicles has begun to be revealed, and new players in this delicate molecular interplay have been exposed., (© 2015 S. Karger AG, Basel.)

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., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

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., (© 2014 British Association of Dermatologists.)

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., (Published by Elsevier Ltd.)

Histone deacetylases (HDACs) are present in the epidermal layer of the skin, outer root sheath, and hair matrix. To investigate how histone acetylation affects skin morphogenesis and homeostasis, mice were generated with a K14 promoter-mediated reduction of Hdac1 or Hdac2. The skin of HDAC1 null (K14-Cre Hdac1(cKO/cKO)) mice exhibited a spectrum of lesions, including irregularly thickened interfollicular epidermis, alopecia, hair follicle dystrophy, claw dystrophy, and abnormal pigmentation. Hairs are sparse, short, and intermittently coiled. The distinct pelage hair types are lost. During the first hair cycle, hairs are lost and replaced by dystrophic hair follicles with dilated infundibulae. The dystrophic hair follicle epithelium is stratified and is positive for K14, involucrin, and TRP63, but negative for keratin 10. Some dystrophic follicles are K15 positive, but mature hair fiber keratins are absent. The digits form extra hyperpigmented claws on the lateral sides. Hyperpigmentation is observed in the interfollicular epithelium, the tail, and the feet. Hdac1 and Hdac2 dual transgenic mice (K14-Cre Hdac1(cKO/cKO) Hdac2(+/cKO)) have similar but more obvious abnormalities. These results show that suppression of epidermal HDAC activity leads to improper ectodermal organ morphogenesis and disrupted hair follicle regeneration and homeostasis, as well as indirect effects on pigmentation.

Although, of no vital value, hair plays a significant role in expressing any person's psychosocial status. Many cosmetic and styling methods are available for hair. This study aimed to examine the microscopic changes in women with hair coloring, hair waving, or hair ironing in comparison with normal controls. In a cross-sectional study, 154 Iranian women were recruited and categorized in 4 groups: controls (n = 35) who had not dyed, waved or ironed their hair within the last 6 months; dyed-hair group (n = 49) who had dyed their hair using standard chemical hair colors at least three times within the last 6 months; waved-hair group (n = 35) who had frizzled their hair within the last 6 months and ironed-hair group (n = 35) who had ironed their hair at least 3 times a weak using a temperature more than 30 degrees C within the last 6 months. Hair samples of all four groups were examined microscopically, and the results were compared with the controls. The rate of abnormal findings was 17.1% in the controls, 53.1% in the dyed-hair group, 45.7% in the waved-hair group, and 54.3% in the ironed-hair group. Abnormal findings were significantly more frequent in the last three groups comparing with the controls (p < 0.05). Trichorrhexis was 17.1, 34.7, 40 and 11.4%; kinking was 0, 2, 2.9 and 25.7%; pseudo pili-annulati was 0, 6.1, 0 and 17.1%; trichonodosis was 0, 6.1, 0 and 0%; tracheoschises was 0, 2, 2.9 and 0% and trichoptilosis was 0, 2, 0 and 0% in the mentioned groups, respectively. Based on the results of the present study, hair coloring, waving and ironing all can induce abnormalities in the hair in comparison with the hairs of nonusers.

Pili annulati (PA) is a rare, benign, autosomal-dominant or sporadic hair shaft disorder characterized by scalp hair with a banded or speckled appearance. We present 2 American families with PA and highlight the characteristic clinical and microscopic features. Among the 2 families, a total of 11 individuals with PA were identified, spanning 3 generations in family 1 and 4 generations in family 2.

Pili annulati is a disorder that produces a spangled appearance to the hair, caused by alternating light and dark banding of hair shafts. This phenomenon is created by abnormal cavities in the cortex of the hair shaft, which produces lighter bands seen on clinical examination. Complications of pili annulati are limited; the most noteworthy complication is increased breakage secondary to weathering of the abnormal hair shafts. We report a case of a 14-year-old adolescent girl with pili annulati and progressive hair loss of 2 months' duration. Most of her hairs were notably short, spangled, and lusterless with light and dark banding observed with handheld magnification. Light microscopy demonstrated alternating light and dark bands, and the dark bands had the typical appearance of air-filled spaces. Gentler hair grooming practices were recommended, and at a follow-up visit, the appearance of the hair had improved with darker and longer shafts. This case should alert clinicians to look for pili annulati when hair fragility is present.

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., (Copyright © 2013 S. Karger AG, Basel.)

An 86-year-old woman slowly developed a solitary 0.3 3 0.2-cm papule on the left lower eyelid. Complete excision disclosed a honeycombed lesion composed of interlacing basaloid strands unattached to the epidermis but rather extending into the dermis from a dilated hair follicle. The diagnosis was a solitary basaloid follicular hamartoma that can also occur in multiple, generalized, and inherited forms, sometimes with an associated systemic disease. The lesion exhibited a distinctive CD34-positive, mildly cellular myxoid stroma with many CK20-positive Merkel cells scattered within the basaloid cellular strands, which exhibited BCL-2 positivity only within the outermost cells bordering the stroma. These immunohistochemical features are the opposite of those displayed by basal cell carcinomas, which require more aggressive surgical management. Besides basal cell carcinomas, the differential diagnosis of basaloid follicular hamartoma includes fibrofolliculoma, tumor of the follicular infundibulum, poroma, and trabecular (Merkel cell) carcinoma.

Objective: To describe the histologic features of canine distichiasis using excised tarsoconjunctival specimens that included roots of distichiatic cilia., Procedures: The study group included 21 strips of cilia-bearing tarsoconjunctiva resected from 20 dogs with distichiasis. Eyelid tissue specimens were also collected from 11 euthanized dogs without distichiasis to serve as controls. All flat mount preparations were processed for histologic examination, and serial sections were stained with hematoxylin-eosin (H&E). A total of 157 slides were examined for the study group to describe the follicles and path of the distichiatic hairs and determine their potential connection with the tarsal glands. A total of 82 slides were examined for the control group., Results: In 19 of the 20 dogs with distichiasis, serial sections of the specimens identified anatomic segments of hair follicles located abnormally in the eyelid tarsus and associated with the aberrant cilia. They appeared as hair bulbs adjacent to tarsal glands, middle portions of hair follicles located between sebaceous lobules, and single or multiple hair shafts present within the sebaceous duct. The tarsal glands in the cilia-bearing tarsoconjunctiva were not different from those of the controls, in which no distichiatic hair bulbs or shafts were observed., Conclusions: These results demonstrate that adventitious cilia are not associated with histologic changes of the tarsal glands, and appear to arise from ectopic hair follicles present in the tarsus. Canine distichiasis may result from anomalous regulation of morphogenesis of hair follicles in the mesenchymal tissue of the tarsal plate., (© 2011 American College of Veterinary Ophthalmologists.)