Segmental Neurofibromatosis

Segmental neurofibromas are the rarest variant of neurofibromatosis. We describe one such case in a 34-year-old man with multiple subcutaneous swellings in the posterior aspect of the left lower limb.

NF1-like optic pathway gliomas in children: clinical and molecular characterization of this specific presentation

Background

Pediatric neurofibromatosis type 1 (NF1)–associated optic pathway gliomas (OPGs) exhibit different clinico-radiological features, treatment, and outcome compared with sporadic OPGs. While NF1-associated OPGs are caused by complete loss-of-function of the NF1 gene, other genetic alterations of the RAS-MAPK pathway are frequently described in the sporadic cases. We identified a group of patients who presented OPGs with typical radiological features of NF1-associated OPGs but without the NF1 diagnostic criteria. We aim to investigate into the possible molecular mechanisms underlying this “NF1-like” pediatric OPGs presentation.

Methods

We analyzed clinico-radiological features of 16 children with NF1-like OPGs and without NF1 diagnostic criteria. We performed targeted sequencing of the NF1 gene in constitutional samples (n = 16). The RAS-MAPK pathway major genes were sequenced in OPG tumor samples (n = 11); BRAF FISH and IHC analyses were also performed.

Results

In one patient’s blood and tumor samples, we identified a NF1 nonsense mutation (exon 50: c.7285C>T, p.Arg2429*) with ~8% and ~70% VAFs, respectively, suggesting a mosaic NF1 mutation limited to the brain (segmental NF1). This patient presented signs of neurodevelopmental disorder. We identified a somatic alteration of the RAS-MAPK pathway in eight tumors: four BRAF activating p.Val600Glu mutations, three BRAF:KIAA oncogenic fusions, and one putative gain-of-function complex KRAS indel inframe mutation.

Conclusions

NF1-like OPGs can rarely be associated with mosaic NF1 that needs specific constitutional DNA analyses for diagnosis. Further studies are warranted to explore unknown predisposition condition leading to the NF1-like OPG presentation, particularly in patients with the association of a neurodevelopmental disorder.

Congenital extra calvarial plexiform neurofibroma in occipito-cervical region with Occipital bone defect with neurofibromatosis type 1 and segmental neurofibromatosis: Case report and review of literature

Plexiform neurofibroma (PNF) of the scalp is an extremely rare lesion reported in association with neurofibromatosis (NF). Occipital location of PNF is even more infrequent; we reported one pediatric case of PNF in occipito-cervical region with multiple small occipital bone defects and associated with NF-1.

Segmental neurofibromatosis with deep schwannoma

An elderly patient presented with two clusters of asymptomatic fleshy and pedunculated papules. Biopsy of the papules was consistent with neurofibromas. Decades prior she had undergone a surgery for the excision of a large schwannoma. Given her lack of other neurofibromatosis findings, the patient was diagnosed with multisegmental neurofibromatosis (multi-SN) with deep schwannoma, a possible new phenotype of SN. Because this entity may be associated with internal malignancy, it is important to screen and educate these patients as well as to provide regular follow-up.

Segmental neurofibromatosis

Segmental neurofibromatosis or type V neurofibromatosis is a rare genodermatosis characterized by neurofibromas, café-au-lait spots and neurofibromas limited to a circumscribed body region. The disease may be associated with systemic involvement and malignancies. The disorder has not been reported yet in the Polish medical literature. A 63-year-old Caucasian woman presented with a 20-year history of multiple, flesh colored, dome-shaped, soft to firm nodules situated in the right lumbar region. A histopathologic evaluation of three excised tumors revealed neurofibromas. No neurological and ophthalmologic symptoms of neurofibromatosis were diagnosed.