Plexiform neurofibroma (PF) is a rare benign variant belonging to a subtype of neurofibromatosis type 1 that forms bulging or deforming masses arising from the peripheral nerve sheath. These masses involve surrounding connective tissue or dermal layers, leading to multiple cutaneous changes and certain characteristic appearances. It is these appearances that aid in the diagnosis of PF. We have encountered two distinct patients diagnosed with this disorder. While one patient was clinically and pathologically confirmed for PF, the other had no characteristic cutaneous changes. The diagnosis was made with postoperative histopathology and confirmed with an immunohistochemical examination. There are various modalities in the management of PFs, with surgery being a mainstay in the treatment of disfiguring large PFs, especially in resource-restrained settings. In view of high recurrence rates, postoperative clinical follow-up is a must. This paper describes these patients\' typical and atypical clinical presentation and subsequent management.

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Neurofibromatosis type 1 (NF-1) is the most common neurocutaneous syndrome. It is inherited in an autosomal dominant manner, with many patients having the syndrome as the result of a de novo mutation. NF-1 is caused by a mutation in the NF-1 gene located on the chromosome 17q11.2. NF-1 gene mutations result in the absence or reduced function of neurofibromin protein, thereby promoting tumor development and other clinical findings. NF-1 is fully penetrant, and it is commonly manifested by café-au-lait macules, axillary and/or inguinal freckling, neurofibromas, and Lisch nodules in the eyes. Skeletal manifestations include scoliosis, short stature, long bone dysplasia, and pseudoarthrosis. Rarely, NF-1 can manifest lambdoid suture defects. This report describes the case of a 12-year-old neurofibromatosis patient who presented to the pediatric clinic with a palpable posterior scalp defect, as well as café-au-lait macules and Lisch nodules. Diagnosis of NF-1 was made clinically. MRI and CT scan were done, and the patient was diagnosed with a lambdoid suture defect that is not associated with plexiform neurofibroma. Moreover, whole exome sequence (WES) was done, and diagnosis of NF-1 was confirmed. Watchful waiting and continuous monitoring were the management of choice for this case.

Legius syndrome (LS) is a rare and underrecognized disorder that is often misdiagnosed as neurofibromatosis type 1 (NF1). It is characterized by café-au-lait macules without the tumoral manifestations of NF1. We report the case of an 11-year-old patient with multiple café-au-lait macules and intertriginous freckling who was admitted for bloody stools, joint pain, and weight loss. His clinical and endoscopic findings were consistent with inflammatory bowel disease (IBD). He also met the clinical diagnostic criteria for NF1 but not for LS. Genetic testing played a pivotal role in the differential diagnosis and revealed a loss-of-function mutation in the SPRED1 gene, confirming the diagnosis of LS. This is the first reported case of a patient with IBD and LS. The subtle manifestations of LS make it an underdiagnosed disease, which reduces the likelihood of it being diagnosed in association with other diseases, such as IBD. There are, however, 10 published case reports linking IBD and NF1, and some pathophysiological mechanisms have been proposed. Continued reporting will help clarify the relationship between IBD and RASopathies such as NF1 and LS.

Atopic dermatitis (AD) is a chronic immune-mediated disease characterized by intense pruritis, causing inflammation, itching, and redness of the skin. Dupilumab is a human monoclonal antibody that has been approved for the treatment of atopic dermatitis. It has also been linked with various adverse effects, most of them confined to the injection site. Café-au-lait-macules are benign pigmented lesions of the skin, usually seen in people with genetic disorders. We present a case of café-au-lait macules as an adverse effect of dupilumab therapy in a patient with atopic dermatitis. The patient in this case had been receiving dupilumab therapy for atopic dermatitis. The eczematous lesions had seen improvement; however, the patient presented with CALMs on follow-up, which seem to be linked with dupilumab therapy.

BACKGROUND: Piebaldism is a rare, autosomal dominant, and congenital pigmentary disorder characterized by stable depigmentation of the skin and white forelock. Mutations in KIT or SLUG genes result in piebaldism. Most individuals with piebaldism have a family history of the disorder.
METHODS: In this paper, we report a case of piebaldism with café-au-lait macules resulting from a novel mutation of KIT gene c.1982C > T (p.Thr661Ile) in a three-generation Chinese family. The whole-exome sequencing, mitochondrial gene 3000X, and bioinformatics tools were used to identify the mutation in this new-found pedigree. In addition, we searched the databases of \"Punmed, Chinese National Knowledge Infrastructure, CMJD, WANFANG MED ONLINE\", reviewed 88 cases of piebaldism caused by KIT gene mutation, and summarized the relationship between clinical phenotype and genotype of piebaldism through logistic regression and other statistical methods.
RESULTS: The proband and her affected mother carried a heterozygous c.1982C > T missense mutation (p.Thr661Ile) on KIT gene. Bioinformatics analysis hinted that it had potential pathogenicity. The data showed that piebaldism patients with cafè-au-lait macules had KIT mutations almost located in the intracellular tyrosine kinase domain and were mostly related to the severe clinical phenotype of piebaldism.
CONCLUSIONS: The new heterozygous c.1982C > T missense mutation on KIT caused piebaldism with café-au-lait macules in this Chinese family. This study provides a new reference index for clinicians to judge the severity of clinical phenotypes of piebaldism, broadens the understanding of the correlation between clinical phenotypes and genotypes of piebaldism, and provides reference of genetic counseling and prenatal diagnosis for affected families.

UNASSIGNED: Constitutional mismatch repair deficiency (CMMRD) is a rare autosomal recessive disease carrying an increased risk of cancers (paediatric tumours of central nervous system, haematolymphoid malignancies along with gastrointestinal (GI) cancer(s), which are usually seen in the second and third decades), leading to syndromic presentation. Causal mutations are detected in DNA mismatch repair (MMR) genes, including MLH1, PMS2, MSH2 and MSH6 that are also known for their established role in Lynch syndrome. We describe a case of CMMRD with an earlier (first decade of life) presentation of mediastinal acute lymphoblastic lymphoma and colorectal malignancy.
UNASSIGNED: A 5-year-old boy presented with respiratory complaints, bilateral cervical lymphadenopathy, multiple café-au-lait macules (CALMs) on the lower back and history of parental consanguinity with the death of three sisters due to brain tumour within 6 months of diagnosis. Computerised tomographic scan chest revealed a huge mediastinal mass. The patient underwent a trucut biopsy of the mass. The results were significant for a pre-T-cell acute lymphoblastic lymphoma. Suspicion of CMMRD was raised based on a combination of factors described above. A panel of MMR proteins was applied on the biopsy tissue that revealed loss of nuclear expression of MLH1 and PMS2 immunostaining in tumour cells with positive external controls. While on maintenance therapy for lymphoma, about a year later, the patient developed subacute intestinal obstruction due to a stenosing polypoidal circumferential tumour in the mid-sigmoid colon found on flexible sigmoidoscopy that was followed by endoscopic biopsies and insertion of a fully covered self-expanding metallic adult biliary stent with a diameter of 10 mm and length of 6 cm leading to immediate relief of obstruction. Biopsies revealed adenocarcinoma with neuroendocrine differentiation. Metastatic tumour deposits were seen in the omentum, anterior abdominal wall and the left peritoneal wall.
UNASSIGNED: Earlier (first decade) presentation of GI malignancy warrants that an earlier screening through radiological scans for any possible tumours and MMR protein expression analysis (loss in tumour plus normal non-tumour cells) are essential in patients having CALMs and family history of paediatric tumours.

Neurofibromatosis type 1 (NF1) can cause vascular complications even in undiagnosed NF1 patients. A ruptured aneurysm of the branches of the subclavian artery is a rare but life-threatening event, and the hemorrhage can cause upper airway obstruction. We present a case of NF1 patient with a ruptured transverse cervical artery aneurysm, which led to a nearly obstructed airway. A 52-year-old man who was not previously diagnosed with NF1 presented with sudden pain from the left shoulder to the neck. Since childhood, he has had multiple cutaneous neurofibromas and café-au-lait macules, and freckling in the bilateral axillae. His swollen left side of the neck and left shoulder suggested a hematoma, which compressed the upper airway. Contrast-enhanced computed tomography revealed a cervical hematoma caused by a ruptured aneurysm of the transverse cervical artery. We performed awake fiberoptic intubation because a difficult airway was predicted and surgical airway management may have been impossible due to the anterior cervical hematoma. His airway was secured, and his aneurysm was successfully treated by coil embolization. Based on his cutaneous findings, he was finally diagnosed with NF1. Those who have café-au-lait macules and cutaneous neurofibromas may present with acute cervical hematoma, and it is important to consider the possibility of ruptured aneurysms in the neck region. When patients develop an acute cervical hematoma that causes an acute upper airway obstruction, emergency physicians should consider awake fiberoptic intubation to secure the airway.

To investigate the variant spectrum and genotype-phenotype correlations in a Turkish cohort with Neurofibromatosis Type-1 (NF1).
We retrospectively investigated the clinical and molecular data of 138 NF1 patients from 129 families who had been followed-up for a median of 3.9 (1.25-18.5) years.
NF1 sequencing revealed 73 different intragenic variants, 19 of which were novel. Seven large deletions were detected by multiplex ligation-dependent probe amplification (MLPA) analyses. The total detection rate of pathogenic NF1 variants was found to be 87.1%. Comparing age groups, cutaneous neurofibromas, freckling, and Lisch nodules were more prevalent in patients older than 12 years (p > .05). Optic glioma detected in 17.3% of the patients and was significantly more common before the age of 6 (p > .001). Other solid tumors developed in 5% of the patients. There was no genotype-phenotype correlation between patients with truncating and nontruncating variants. However, six out of seven patients with large deletions had significant developmental delay, one patient with the c.2970_2972delAAT (p.Met992del) variant had only typical pigmentary features, and another patient with the c.4267A > G (p.Lys1423Glu) variant had CALMs, freckling, neurofibromas, and Noonan-like phenotype.
We described 19 novel variants and seven large deletions in NF1. Applying MLPA assay in NF1 is useful in expanding the molecular diagnosis. Although very limited genotype-phenotype correlation has been reported in NF1, the fact that specific phenotypic findings were observed in our patients with large deletions and two intragenic variants supports the studies published recently.

BACKGROUND: Constitutional mismatch repair deficiency (CMMRD) is caused by biallelic pathogenic variants in one of the mismatch repair genes, and results in early onset colorectal cancer, leukemia, brain tumors and other childhood malignancies. Here we report a case of CMMRD with compound heterozygous variants in the MSH6 gene, including a de novo variant in multiple colorectal cancers.
METHODS: An 11-year-old girl, who presented with multiple spots resembling café-au-lait macules since birth, developed abdominal pain, diarrhea and bloody stool over two months. Colonoscopy revealed multiple colonic polyps, including a large epithelial tumor, and pathological examination revealed tubular adenocarcinoma. Brain magnetic resonance imaging (MRI) showed an unidentified bright object (UBO), commonly seen in neurofibromatosis type 1 (NF1). Genetic testing revealed compound heterozygous variants, c. [2969T > A (p.Leu990*)] and [3064G > T (p.Glu1022*)] in the MSH6 gene; c.2969T > A (p.Leu990*) was identified as a de novo variant.
CONCLUSIONS: We present the first report of a CMMRD patient with a de novo variant in MSH6, who developed colorectal cancer in childhood. CMMRD symptoms often resemble NF1, as observed here. Physicians should become familiar with CMMRD clinical phenotypes for the screening and early detection of cancer.