Giant Pelvic Neurofibroma in Patient with Plexiform Sciatic Neurofibroma and Neurofibromatosis Type 1

BACKGROUND: Neurofibromatosis is a genetic disease with an autosomal dominant type of inheritance. It is a multisystem disease in which, besides skin manifestations, there is a possibility for the involvement of other organs and systems, and an atypical variant of neurofibromatosis type 1 can also be observed- the so-called plexiform neurofibroma. In patients with this inherited disease, mortality is higher due to the existing risk for malignant transformation and development of malignant peripheral nerve sheath tumours (MPNSTs) or neurofibrosarcoma. CASE REPORT: We present a 25-year-old woman with neurofibromatosis type 1 and a family history of the disease-father and grandmother with NF-1, with fatal outcome in the grandmother as a result of malignant transformation to neurofibrosarcoma. The patient has clinical data for multiple cafés- au- lait spots on the skin of the trunk, upper and lower limbs, and plexiform tumour formation in the seating area. From the performed imaging diagnostic there are available MRT data for 1) giant pelvic neurofibroma, 2) plexiform giant neurofibroma in the subcutaneous fat on the right thigh and gluteal fat tissue to the right, passing through the midline in the area of the external genitalia, leading to deformation of the front wall of the sacrum with bilateral meningoceles and 3) diffuse involvement of the bladder wall from the process in the area of the trigonum vesicae felleae/the two urethral ostium, as well as 4) the presence of neurofibromas in the course of the iliac vessels on the right. Surgical removal of the oval pelvic formation, identified as neurofibroma was planned, as well as the initiation of systemic therapy with Sirolimus for the plexiform sciatic formation, infiltrating the bladder. CONCLUSION: Neurofibromatosis type-1 is a problematic disease due to the parallel systemic involvement of different organs and systems, which can be both limited and diffuse. Limited tumour lesions in the form of neurofibromas with diverse localisation (as in the patient we describe) could be surgically removed without difficulty. On the other hand, the diffuse involvement of internal organs within a giant, network-3spreading plexiform neurofibromas (as in the described patient) makes interdisciplinary interventions impossible, and therefore therapeutic alternatives should be considered.