CASE 13560 Published on 06.11.2016

Recurrent abdominal and pelvic plexiform neurofibroma:CT and MRI findings

Section

Uroradiology & genital male imaging

Case Type

Clinical Cases

Authors

Funda Dinç Elibol1, Cenk Elibol1, Özcan Dere2, Süha Gül1, Okay Nazlı2

Department of Radiology1, Mugla Sitki Koçman University Education and Research Hospital, Mugla/Turkey
Department of General Surgery2, Mugla Sitki Koçman University Education and Research Hospital, Mugla/Turkey
Email:fundadi@yahoo.com
Patient

55 years, male

Categories
Area of Interest Abdomen ; Imaging Technique CT, MR
Clinical History
A 55-year-old man presented with right upper quadrant pain and abdominal distension. On physical examination, incisional hernia and abdominal tenderness were detected. The patient had surgery 20 years ago due to symptoms of intra-abdominal and pelvic neurofibromas.
Imaging Findings
In our patient, abdominal sonogram shows intraabdominal, pelvic, and subcutaneus oval and tubular, smooth masses with hypoechoic midly heterogenous echotexture. CT scans reveal paraspinal, abdominal, pelvic, pararectal, subcutaneous hypodnese masses. Focal hyperattenuating areas are present in some of the neurofibromas. MRI shows pelvic and inguinal target-like lesions, abdominal and pararectal neurofibromas that are oval and septated markedly hyperintense on T2 weighted images and hypointense on T1 weighted images.
Discussion
Neurofibromatosis type 1(NF1) is one of the most common autosomal dominant disorders that affects approximately 1:3000 individuals [1]. Mutations of the NF1 gene, which is located at chromosome 17, lead to abnormal tumour suppression [2]. NF1 is diagnosed based on clinical criteria. The presence of at least two diagnostic criteria (cafe-au-lait macules, neurofibromas, Lisch nodules, axillary or inguinal freckling, optic glioma, distinctive osseous lesions or first-degree relatives with NF1) is necessary for diagnosis of NF1. The clinical expression of this phakomatosis is extremely variable [3].
Neurofibromas are benign nerve sheath tumours and may involve the skin, soft tissues, or viscera. Plexiform neurofibromas are network-like growths of tumour involving multiple fascicles of a nerve, leading to a diffuse mass of thickened nerve fibres surrounded by proteinaceous matrix which are pathognomonic for NF1 [4]. Local recurrences are common after surgical resection [5]. In this case, the patient had surgery twice 20 years ago and pathology revealed plexiform neurofibromas. Multimodality imaging showed recurrent intraabdominal and pelvic plexiform neurofibromas.
The most common site of visceral involvement in NF1 is the gastrointestinal tract (10%-25% of patients). Paraspinal and sacral neurofibromas are the most common abdominal neoplasm in NF1. The majority of gastrointestinal neurofibromas are asymptomatic. Genitourinary neurofibromas are rare. The bladder is the most common genitourinary organ affected by neurofibromas and rarely asymptomatic when involved [7].
Sonographic views of neurofibromas are typically well-defined oval homogeneously or heterogenously hypoechoic masses [7]. On CT, plexiform neurofibromas are typically bilateral, symmetrical low-attenuation smooth masses in parapsoas or presacral location. The attenuation values range between 20-25 HU in nonenhanced and 30-50 HU in iv-contrast enhanced CT scans [6, 8].
Neurofibromas are typically hypointense on T1 weighted images and heterogenous markedly hyperintense on T2 weighted images. On T2 weighted images high signal represents areas of cystic degeneration or myxoid matrix and the low signal represents collagen and fibrous tissue [9, 10]. Plexiform neurofibromas characteristically have a target-like appearance on T2 weighted MR images, with well-defined central decreased signal intensity and peripheral increased signal intensity. Neurofibromas enhance following administration of gadolinium [4, 10]. Ring-like or septated pattern, that is typical of plexiform neurofibromas, is best observed on T2 weighted images and contrast-enhanced T1 weighted images [10]. Since the MRI features of abdominal and plevic neurofibromas are characteristic, diagnosis can be based on MRI and other lesions can be ruled out. MRI is the valuable tool in initial and follow up evaluation of this phakomatosis.
Differential Diagnosis List
Abdominal and pelvic plexiform neurofibroma
Lymph node
Malignant peripheral nerve sheath tumour
Final Diagnosis
Abdominal and pelvic plexiform neurofibroma
Case information
URL: https://www.eurorad.org/case/13560
DOI: 10.1594/EURORAD/CASE.13560
ISSN: 1563-4086
License