Mast Cells in Human Cutaneous Neurofibromas: Density, Subtypes, and Association with Clinical Features in Neurofibromatosis 1

<b><i>Background:</i></b> Cutaneous neurofibromas (cNFs) are hallmarks of neurofibromatosis 1 (NF1) and cause the main disease burden in adults with NF1. Mast cells are a known component of cNFs. However, no comprehensive characterization of mast cells in cNFs is available, and their contributions to cNF growth and symptoms such as itch are not known. <b><i>Methods:</i></b> We collected 60 cNFs from ten individuals with NF1, studied their mast cell proteinase content, and compared the mast cell numbers to selected clinical features of the tumors and patients. The tumors were immunolabeled for the mast cell markers CD117, tryptase, and chymase, and the percentage of immunopositive cells was determined using computer-assisted methods. <b><i>Results:</i></b> The median proportions of positive cells were 5.5% (range 0.1–14.4) for CD117, 4.0% (1.2–7.0) for tryptase, and 5.0% (1.1–15.9) for chymase. The median densities of cells immunopositive for CD117, tryptase, and chymase were 280, 243, and 250 cells/mm², respectively. Small tumors, growing tumors, and tumors from patients below the median age of 33 years displayed a high proportion of mast cells. Cells expressing both tryptase and chymase were the predominant mast cell type in cNFs, followed by cells expressing chymase only. <b><i>Conclusion:</i></b> The results highlight the abundance of mast cells in cNFs and that their number and subtypes clearly differ from those previously reported in unaffected skin.

[REiNS] Validating Techniques for Measurement of Cutaneous Neurofibromas: Recommendations for Clinical Trials

Objective:To assess the reliability and variability of digital calipers, 3D photography, and high frequency ultrasound (HFUS) for measurement of cutaneous neurofibromas (cNF) in patients with neurofibromatosis type 1 (NF1).Background:cNF affect virtually all patients with NF1 and are a major source of morbidity. Reliable techniques for measuring cNF are needed to develop therapies for these tumors.Methods:Adults with NF1 were recruited. For each participant, six cNF were assessed independently by three different examiners at five different timepoints using digital calipers, 3D photography, and HFUS. The intraclass correlation coefficient (ICC) was used to assess intra- and inter-rater reliability of linear and volumetric measurements for each technique, with ICC values >0.90 defined as “excellent” reliability. The coefficient of variation (CV) was used to estimate the minimal detectable difference (MDD) for each technique.Results:57 cNF across 10 participants were evaluated. The ICC for image acquisition and measurement was >0.97 within and across examiners for HFUS and 3D photography. ICC for digital calipers was 0.62–0.88. CV varied by measurement tool, linear vs. volumetric measurement, and tumor size.Conclusions:HFUS and 3D photography demonstrate “excellent” reliability whereas digital calipers have “good” to “excellent” reliability in measuring cNF. The MDD for each technique was used to create tables of proposed thresholds for investigators to use as guides for clinical trials focused on cNF size. These criteria should be updated as the performance of these endpoints are evaluated.

REiNS: Measuring the Impact of Cutaneous Neurofibromas on Quality of Life in Neurofibromatosis Type 1

Objective:In order to explore the use of Skindex scoring in NF1 patients across multiple clinical sites, and inform design of additional quality of life measures, we analysed correlations between skindex, site and clinical parameters for 79 patients with NF1 from specialised clinics in Sydney, NSW Australia (RNS) and Minneapolis Minnesota, USA (UMN).Methods:The relationship between the clinical factors and Skindex scores were explored by clinic site and overall.Results:40 subjects were recruited from RNS and 39 from UMN. Female sex, total number of cNFs, and whether cNFs were present on the face, correlated highly with skindex and not Riccardi scores. The UMN site had lower average scores, but these differences were almost entirely removed after adjusting for age, sex, facial CNFs and total CNF number.Conclusions:The development of cutaneous neurofibromas (cNFs) in adolescence and adulthood in neurofibromatosis, type 1 (NF1) often lead to progressive disfigurement and discomfort, and are among one of the most common reasons for patients to seek medical treatment. Skindex has been used to assess skin related quality of life in NF1 previously but is not specific to NF1. These findings highlight the need for a low threshold for referral to Dermatologists for all patients with Neurofibromatosis Type 1 regardless of the severity of disease. The finding that facial CNFs and higher total number of CNFs correlates with poorer skin related quality of life, may benefit design of more specific NF1 skin related quality of life measures.

Case Report: Mosaicism of a novel nonsense variant in the neurofibromin gene underlies a mosaic generalized NF1 phenotype

Neurofibromatosis 1 (NF1) is a neurocutaneous syndrome characterized by multiple café-au-lait macules, cutaneous neurofibromas or plexiform neurofibromas, iris Lisch nodules, axillary and inguinal freckling. Mosaicism in NF1 can either present as a generalized disease, or in a localized (segmental) manner. Mosaic generalized NF1 may have presentations that are similar to generalized NF1 or have a milder phenotype and hence may be under-recognised in clinical practice. We report a nonsense mutation in the NF1 gene in a 55-year old Chinese male with the mosaic generalized phenotype. He reported noticing increasing numbers of skin-colored papules over his face, neck, back and abdomen when he was about 40 years old. From both next-generation and Sanger sequencing data, the variant appeared to be mosaic and present at about 24%. It is in exon 39 and has not been reported in any database or published literature.

Case Report: Mosaicism of a novel nonsense variant in the neurofibromin gene underlies a mosaic generalized NF1 phenotype

Neurofibromatosis 1 (NF1) is a neurocutaneous syndrome characterized by multiple café-au-lait macules, cutaneous neurofibromas or plexiform neurofibromas, iris Lisch nodules, axillary and inguinal freckling. Mosaicism in NF1 can either present as a generalized disease, or in a localized (segmental) manner. Mosaic generalized NF1 may have presentations that are similar to generalized NF1 or have a milder phenotype and hence may be under-recognised in clinical practice. We report a nonsense mutation in the NF1 gene in a 55-year old Chinese male with the mosaic generalized phenotype. He reported noticing increasing numbers of skin-colored papules over his face, neck, back and abdomen when he was about 40 years old. From both next-generation and Sanger sequencing data, the variant appeared to be mosaic and present at about 24%. It is in exon 39 and has not been reported in any database or published literature.

A Clinicopathologic Study on the Role of Estrogen, Progesterone, and Their Classical and Nonclassical Receptors in Cutaneous Neurofibromas of Individuals With Neurofibromatosis 1

Objectives To evaluate the expression of progesterone receptor (PR), estrogen receptor (ER), and G protein–coupled estrogen receptor 1 (GPER-1) in cutaneous neurofibromas (cNFs) and their correlation with demographic, clinical, and laboratory data of individuals with neurofibromatosis 1 (NF1). The association of PROGINS polymorphism and PR expression in cNFs, as well as the serum steroidal hormones and the number of cNFs, was investigated. Methods The sample comprised 80 large and 80 small cNFs from 80 individuals with NF1. PR, ER, GPER-1, and Ki-67 expression were investigated by immunohistochemistry in tissue micro- and macroarrays and quantified using a digital computer-assisted method. The number of cNFs, the levels of serum 17β estradiol and progesterone, and the PROGINS polymorphism were identified. Results Twelve (8.5%) small cNFs were weakly positive for ER, 131 (92.3%) cNFs expressed PR, and all (100%) cNFs expressed GPER-1. Large cNFs showed a higher expression of PR (P &lt; .0001) and GPER-1 (P = .019) and had a higher intensity of staining for these receptors (P &lt; .0001). The cell proliferation index was positively correlated with PR (P = .001). Persons with more cNFs had higher serum levels of progesterone (P = .001). Conclusions These findings emphasize the role of estrogen and progesterone in cNF development and suggest that these hormones may act on cNF cells via a noncanonical pathway through GPER-1.