Large germline deletions of the CYLD gene in patients with Brooke-Spiegler syndrome and multiple familial trichoepithelioma. Am J Dermatopathol. 2014;36:868-874. [PMID: 25347032 DOI: 10.1097/DAD.0000000000000068]

A Misdiagnosed Familiar Brooke-Spiegler Syndrome: Case Report and Review of the Literature

Aim of the report: Brooke-Spiegler syndrome (BSS) is a rare autosomal dominant disease characterized by the growth of cylindromas, spiradenomas, trichoepitheliomas, or their combination. These neoplasms usually begin in the second decade and progressively increase in number and size over the years. Diagnosis necessitates consideration of family history, clinical examination, histological findings, and genetic analysis. The aim of this paper is to explore the clinical overlap between Brooke-Spiegler syndrome (BSS) and neurofibromatosis type 1 (NF1). We aim to highlight the challenges associated with their differential diagnosis and emphasize the lack of standardized diagnostic criteria and treatment approaches. Case presentation: Hereby, we introduce the case of a 28-year-old male referred for suspicion of neurofibromatosis type 1 (NF1) who initially declined the recommended surgical excision for a scalp mass. After four years, he returned with larger masses of the scalp, and underwent excision of multiple masses, revealing cylindromas, spiradenomas, and spiradenocylindromas. Family history reported similar tumors in his father, who was also diagnosed with NF1 for the presence of multiple subcutaneous lesions on the scalp. Clinical overlap led to a genetic consultation, but testing for CYLD mutations yielded no significant variations. Despite this, the strong family history and consistent findings led to a revised diagnosis of Brooke-Spiegler syndrome, correcting the initial misdiagnosis of NF1 syndrome. Conclusions: Thanks to the evolving landscape of BSS research over the past two decades, its molecular underpinnings, clinical presentation, and histopathological features are now clearer. However, a thorough family history assessment is mandatory when BSS is suspected. It is our belief that a multidisciplinary approach and cooperation between specialists are essential when dealing with BSS. By sharing this case, we hope to underscore the importance of considering BSS as a differential diagnosis, especially in cases with atypical presentations or overlapping features with other syndromes like NF1.

Genetic Testing in CYLD Cutaneous Syndrome: An Update

CYLD cutaneous syndrome (CCS) is an inclusive label for the inherited skin adnexal tumour syndromes Brooke–Spiegler Syndrome (BSS-OMIM 605041), familial cylindromatosis (FC – OMIM 132700) and multiple familial trichoepitheliomas (MFT-OMIM 601606). All three syndromes arise due to germline pathogenic variants in CYLD, a tumour suppressor gene (OMIM 605018). CCS is transmitted in an autosomal dominant pattern, and has variable expressivity, both of the three syndromic phenotypes, and of the severity of tumour burden. Age-related penetrance figures are not precisely reported. The first tumours typically appear during puberty and progressively accumulate through adulthood. Penetrance is typically high, with equal numbers of males and females affected. Genetic testing is important for confirmation of the clinical diagnosis, genetic counselling and family planning, including preimplantation diagnosis. Additionally, identified CCS patients may be eligible for future clinical trials of non-surgical pre-emptive interventions that aim to prevent tumour growth. In this update, we review the clinical presentations of germline and mosaic CCS. An overview of the germline pathogenic variant spectrum of patients with CCS reveals more than 100 single nucleotide variants and small insertions and deletions in coding exons, most frequently resulting in predicted truncation. In addition, a minority of patients have large deletions involving the CYLD gene, intronic pathogenic variants that affect splicing, or inversions. We discuss germline and somatic testing approaches. Somatic testing of tumour tissue, relevant in mosaic CCS, can reveal recurrently detected pathogenic variants when two or more tumours are tested. This can influence genetic testing of children, who may inherit this as a germline variant, and inform genetic counselling and prenatal diagnosis. Finally, we discuss testing technologies that are currently used, their benefits and limitations, and future directions for genetic testing in CCS.

A novel large deletion of the CYLD gene causes CYLD cutaneous syndrome in a Chinese family

BACKGROUND

CYLD cutaneous syndrome (CCS; syn. Brooke-Spiegler syndrome) is a rare autosomal dominant hereditary disease characterized by multiple adnexal skin tumors including cylindromas, spiradenomas, and trichoepitheliomas. More than 100 germline mutations of the cylindromatosis (CYLD) gene have been reported in CCS and most of them are frameshift mutations or small alterations.

METHODS

We identified a large, three-generation Chinese family with CCS, which consisted of 18 living family members, including six affected individuals. To explore the molecular biology of this family, we carried out targeted next-generation sequencing and Affymetrix CytoScan HD SNP array to analyze the mutation in the CYLD gene.

RESULTS

A novel large deletion mutation, NC_000016.9:g.(50826498_50827517)_(50963389-50967346)del was found in the proband of this family. This deletion results in the loss of a nearly 140 kb fragment of the CYLD gene, spanning exons 17 ~ 20, which represent the coding regions of the ubiquitin-specific protease domain. Further quantitative polymerase chain reaction proved that all patients and two proband-related family members carried this large deletion.

CONCLUSIONS

Our study expands the types of mutations in CCS and will undoubtedly provide valuable information for genetic counseling for families affected by the condition.

Diverse presentations of cutaneous mosaicism occur in CYLD cutaneous syndrome and may result in parent-to-child transmission

Background

Clusters of rare cylindroma or spiradenoma tumors are a recurrent clinical presentation, yet conventional genetic testing results in individuals with these tumors are frequently normal.

Objective

To determine if genetic mosaicism accounts for such cases.

Methods

A study of 6 cases from a series of 55 patients who met criteria for diagnostic gene testing for pathogenic CYLD variants over a 5-year period (2012-2017) was performed. A novel genetic assay was used to study DNA from peripheral blood leukocytes and, where possible, matched skin and tumor tissue.

Results

Two patients had mosaic pathogenic CYLD variants in both the blood and skin. One of these patients transmitted a pathogenic variant to her daughter, and we report the novel phenotype of a contiguous gene deletion syndrome involving CYLD. Two patients had recurrent pathogenic variants in skin tumors from a single cluster but none detectable in the blood.

Limitations

The remaining 2 patients had clinical features of mosaicism, but these cases were not solved with the assays used because of a lack of access of fresh tumor tissue.

Conclusion

Genetic mosaicism should be considered in patients presenting with clustered cylindromas, because this may inform genetic testing and counseling of these patients.

Heterozygous Cylindromatosis Gene Mutation c.1628_1629delCT in a Family with Brook-Spiegler Syndrome

Brooke–Spiegler Syndrome (BSS) is a rare genodermatosis characterized by the progressive formation of adnexal skin tumors in the scalp and face, mainly trichoepitheliomas, cylindromas, and spiradenomas. It has also been associated with salivary glands neoplasms. It is due to mutations in the tumor suppressor gene cylindromatosis (CYLD gene) localized on chromosome 16q12−q13. Around 93 mutations have been described. The study of CYLD gene in patients and their relatives is of vital importance to establish the molecular diagnosis and offer appropriate genetic counseling. There is a low risk of malignancy and patients require long-term follow-up. A case of BSS in a family is described. The existence of the genetic mutation at the CYLD gene c. 1628_1629delCT in three of the women affected was demonstrated. This mutation has only been described once in a previous study.

The cylindromatosis (CYLD) gene and head and neck tumorigenesis

Germline CYLD mutation is associated with the development of a rare inheritable syndrome, called the CYLD cutaneous syndrome. Patients with this syndrome are distinctly presented with multiple tumors in the head and neck region, which can grow in size and number over time. Some of these benign head and neck tumors can turn into malignancies in some individuals. CYLD has been identified to be the only tumor suppressor gene reported to be associated with this syndrome thus far. Here, we summarize all reported CYLD germline mutations associated with this syndrome, as well as the reported paired somatic CYLD mutations of the developed tumors. Interestingly, whole-exome sequencing (WES) studies of multiple cancer types also revealed CYLD mutations in many human malignancies, including head and neck cancers and several epithelial cancers. Currently, the role of CYLD mutations in head and neck carcinogenesis and other cancers is poorly defined. We hope that this timely review of recent findings on CYLD genetics and animal models for oncogenesis can provide important insights into the mechanism of head and neck tumorigenesis.

Overexpression of MYB drives proliferation of CYLD-defective cylindroma cells

Cutaneous cylindroma is an adnexal tumour with apocrine differentiation. A predisposition to multiple cylindromas is seen in patients with Brooke-Spiegler syndrome, who carry germline mutations in the tumour suppressor gene CYLD. Previous studies of inherited cylindromas have highlighted the frequent presence of bi-allelic truncating CYLD mutations as a recurrent driver mutation. We have previously shown that sporadic cylindromas express either MYB-NFIB fusion transcripts or show evidence of MYB activation in the absence of such fusions. Here, we investigated inherited cylindromas from several families with germline CYLD mutations for the presence of MYB activation. Strikingly, none of the inherited CYLD-defective (n = 23) tumours expressed MYB-NFIB fusion transcripts. However, MYB expression was increased in the majority of tumours (69%) and global gene expression analysis revealed that well-established MYB target genes were up-regulated in CYLD-defective tumours. Moreover, knock-down of MYB expression caused a significant reduction in cylindroma cell proliferation, suggesting that MYB is also a key player and oncogenic driver in inherited cylindromas. Taken together, our findings suggest molecular heterogeneity in the pathogenesis of sporadic and inherited cutaneous cylindromas, with convergence on MYB activation. © 2016 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Brooke-Spiegler Syndrome and Phenotypic Variants: An Update

Brooke-Spiegler syndrome (BSS) is an inherited autosomal dominant disease characterized by the development of multiple adnexal cutaneous neoplasms most commonly spiradenoma, cylindroma, spiradenocylindroma, and trichoepithelioma. Multiple familial trichoepithelioma (MFT) is a phenotypic variant of the disease characterized by the development of numerous trichoepitheliomas (cribriform trichoblastoma) only. Malignant tumors arise in association with preexisting benign cutaneous neoplasms in about 5-10% of the patients . Apart from the skin, major and minor salivary glands have been rarely involved in BSS patients. Extremely rare is the occurrence of breast tumors (cylindroma). The gene implicated in the pathogenesis of the disease is the CYLD gene, a tumor suppressor gene located on chromosome 16q12-q13. Germline CYLD mutations are detected in about 80-85% of patients with the classical BSS phenotype and in about 40-50% of the individuals with the MFT phenotype using a PCR based approach with analysis of exonic sequences and exon-intron junctions of the CYLD gene. There appears to be no genotype-phenotype correlations with respect to the severity of the disease, the possibility of malignant transformation, and development of extracutaneous lesions.

Report of Three Novel Germline CYLD Mutations in Unrelated Patients with Brooke-Spiegler Syndrome, Including Classic Phenotype, Multiple Familial Trichoepitheliomas and Malignant Transformation

Brooke-Spiegler syndrome is a rare autosomal-dominant genetic disorder characterized by multiple adnexal tumors, including cylindromas, spiradenomas, spiradenocylindromas and trichoepitheliomas. It is caused by germline CYLD mutations commonly leading to a premature stop codon. We here report on 3 novel CYLD mutations in 3 unrelated BSS patients, including the classic phenotype, multiple familial trichoepitheliomas phenotype and malignant transformation. These included c.1821_1826+1delinsCT/L607Ffs*9, c.2666A>T/p.D889V and c.2712delT/p.905Kfs*8. By extending the spectrum of CYLD mutations, better understanding of the molecular mechanisms of BSS can be gained, which might later assist in finding new treatment options.

CYLD GeneticTesting for Brooke-Spiegler Syndrome, Familial Cylindromatosis and Multiple Familial Trichoepitheliomas

The clinical presentation of multiple, rare, skin appendage tumours called cylindromas has been attributed to germline mutations in the tumour suppressor gene <i>CYLD</i> (OMIM 605018). Brooke-Spiegler Syndrome (BSS), familial cylindromatosis (FC) and multiple familial trichoepitheliomas (MFT) (OMIM #605041, #132700, #601606 respectively) differ due to the types of other skin appendage tumour seen together with cylindroma, such as spiradenoma and trichoepithelioma. Previously thought to be separate entities, they are now viewed as allelic variants with overlapping phenotypes, supported by mutation analysis of <i>CYLD</i> . The conditions display autosomal dominant inheritance and affected individuals develop multiple benign skin tumours most commonly on the head and neck. <i>CYLD</i> testing can be performed using PCR and Sanger sequencing for patients with: 1. Multiple cylindromas, spiradenomas or trichoepitheliomas. 2. A single cylindroma, spiradenoma or trichoepithelioma and an affected first-degree relative with any of these tumours. 3. An asymptomatic family member at 50% risk with a known mutation in the family.

Knowledge explosion for monogenic skin diseases

During the past few decades, the investigative tech-nologies of molecular biology - especially sequencing - underwent huge advances, leading to the sequencing of the entire human genome, as well as the identification of several candidate genes and the causative genetic variations that are responsible for monogenic skin diseases. These advances provided a solid basis for subsequent studies elucidating mechanisms of monogenic skin diseases and improving our understanding of common skin diseases. Furthermore, these discoveries also contributed to the development of novel therapeutic modalities for monogenic skin diseases. In this review, we have used the disease spectrum caused by mutations in the CYLD gene - Brooke-Spiegler syndrome, familial cylindromatosis and multiple familial trichoepithelioma type 1 - as a model for demonstrating the knowledge explosion for this group of diseases.