Imaging diagnosis of plexiform neurofibroma- unravelling the confounding features: A report of two cases

The role of multimodality imaging in diffuse pelvicoabdominal plexiform neurofibroma: A rare case report

Pelvicoabdominal plexiform neurofibroma is a rare and complicated form of type 1 neurofibromatosis (NF1), distinguished by developing benign nerve sheath tumors in the pelvis and abdomen. A male patient, aged 26, came to our center with dysuria, abdominal bloating, rectal mucosa prolapses, and trouble walking and moving legs. Physical examination revealed a palpable mass of solid consistency fixed in the pelvic cavity to the abdominal cavity. A large and extensive mass in the pelvic to the abdominal region can be evaluated with multimodality radiological imaging, including ultrasound, computed tomography, and magnetic resonance imaging. Imaging is crucial for diagnosis, evaluation of extension, and early detection of potential malignant transformation in these patients. The patient was scheduled for palliative surgical resection due to the extensive mass; however, he did not survive while waiting for the operation. Pathology examination and immunohistochemical staining revealed positive S-100 protein, indicating the neural crest originate lesion. We report the clinical and radiological features of plexiform neurofibroma in a young male patient, confirmed by pathology examination.

Genetic basis and imaging findings of neurofibromatosis 1 and other somatic overgrowth disorders

Somatic overgrowth disorders comprise a wide range of rare conditions that present with focal enlargement of one or more tissue types. The PI3K-AKT-mTOR pathway is a signalling pathway that induces angiogenesis and cell proliferation, and is one of the most commonly overactivated signalling pathways in cancer. The PI3K-AKT-mTOR pathway can be up-regulated by genetic variants that code for proteins in this pathway, or down-regulated by proteins that inhibit the pathway. Mosaic genetic variations can result in cells that proliferate excessively in specific anatomical locations. The PIK3CA-related overgrowth spectrum (PROS) disorders include CLOVES syndrome, macrodystrophia lipomatosa, and Klippel-Trenaunay syndrome among many. The neurofibromatosis type 1 (NF1) gene encodes neurofibromin which down-regulates the PI3K-AKT-mTOR pathway. Thousands of pathological variants in the NF1 gene have been described which can result in lower-than-normal levels of neurofibromin and therefore up-regulation of the PI3K-AKT-mTOR pathway promoting cellular overgrowth. Somatic overgrowth is a rare presentation in NF1 with a wide range of clinical and radiological presentations. Hypertrophy of all ectodermal and mesodermal elements has been described in NF1 including bone, muscle, fat, nerve, lymphatics, arteries and veins, and skin. The shared signalling pathway for cellular overgrowth means that these radiological appearances can overlap with other conditions in the PIK3CA-related overgrowth spectrum. The aim of this review is to describe the genetic basis for the radiological features of NF1 and in particular compare the appearances of the somatic overgrowth disorders in NF1 with other conditions in the PIK3CA-related overgrowth spectrum.

Intraparotid plexiform neurofibroma: A rare diagnostic challenge

Isolated intraparotid neurofibromas are exceptionally rare and often associated with neurofibromatosis type 1 (NF1). Diagnosing these tumors proves challenging because of the clinical resemblance to primary salivary gland masses. This case report details an 18-year-old with a painful, enlarging parotid mass, diagnosed through fine needle aspiration biopsy (FNAB) revealing myxoid stroma and spindle cells. Magnetic resonance imaging confirmed a plexiform neurofibroma involving the parotid gland and facial nerve. Histopathology validated the diagnosis, emphasizing the importance of cytological and radiological correlation. Notably, the absent NF1 association makes this case unique. Surgical excision with facial nerve reconstruction was performed, highlighting the complexity of managing such rare intraparotid neurofibromas. Awareness of this entity is crucial for accurate diagnosis and appropriate management.

A Child Plexiform Neurofibroma of the Temple Region: A Case Report

Plexiform neurofibroma is a rare variant of neurofibromatosis type 1. Diagnosis is challenging due to the highly variable clinical presentation. Early diagnosis is essential for appropriate treatment and prevention of complications. This report describes a sporadic solitary plexiform neurofibroma in the temporal region of a seven-year-old girl. The growth of the mass began at birth and grew steadily over five years. Subsequently, the mass began to expand rapidly. The patient underwent complete surgical resection under general anesthesia. Histopathological examination revealed a plexiform neurofibroma. In conclusion, surgical excision is the gold standard for cases with symptomatic, visible, large superficial lesions.

A case of plexiform schwannoma arising from the sciatic, tibial, and peroneal nerves

Plexiform schwannoma is a rare subtype of schwannoma. In this report, we present a case of plexiform schwannoma arising from the sciatic, tibial, and peroneal nerves. A 54-year-old man presented with a painful palpable mass extending from the left posterior thigh to the calf. Magnetic resonance imaging showed multiple bead-like nodular structures along the sciatic, tibial, and peroneal nerve pathway. The nodular lesions showed uniform signal intensity on T1-weighted imaging. On T2-weighted imaging, each nodule showed an eccentric area of relatively low signal intensity surrounded by an area of higher signal intensity and a low-intensity rim. Plexiform schwannoma or neurofibroma was considered as the preoperative diagnosis. Because of the patient's severe symptoms and strong desire for relief, tumor enucleation of the largest painful nodule was performed, and plexiform schwannoma was confirmed pathologically.

The Great Imposter: An Atypical Case of Pleomorphic Adenoma With Review of Literature

Pleomorphic adenomas (PA) are the most common type of salivary gland tumors. These slow-growing benign tumors most commonly involve the parotid gland, but can sometimes occur at atypical sites such as the submandibular or minor salivary glands. We describe an atypical case of pleomorphic adenoma with multicentric involvement of the parotid, the submandibular gland, and the parapharyngeal space in a 35-year-old male which mimicked a slow-flow malformation on magnetic resonance imaging (MRI). Diagnosis was confirmed on fine needle aspiration cytology, and conservative approach was opted for the patient in view of perioperative risks. This case highlights the uncommon multicentricity and atypical presentation of PA, challenging the initial differential diagnosis based on MRI features. It also underscores the importance of considering atypical presentations and utilizing accurate diagnostic tools like cytology for managing complex salivary gland tumors.

Diagnosis and Treatment of Peripheral and Cranial Nerve Tumors with Expert Recommendations: An EUropean Network for RAre CANcers (EURACAN) Initiative

The 2021 WHO classification of the CNS Tumors identifies as "Peripheral nerve sheath tumors" (PNST) some entities with specific clinical and anatomical characteristics, histological and molecular markers, imaging findings, and aggressiveness. The Task Force has reviewed the evidence of diagnostic and therapeutic interventions, which is particularly low due to the rarity, and drawn recommendations accordingly. Tumor diagnosis is primarily based on hematoxylin and eosin-stained sections and immunohistochemistry. Molecular analysis is not essential to establish the histological nature of these tumors, although genetic analyses on DNA extracted from PNST (neurofibromas/schwannomas) is required to diagnose mosaic forms of NF1 and SPS. MRI is the gold-standard to delineate the extension with respect to adjacent structures. Gross-total resection is the first choice, and can be curative in benign lesions; however, the extent of resection must be balanced with preservation of nerve functioning. Radiotherapy can be omitted in benign tumors after complete resection and in NF-related tumors, due to the theoretic risk of secondary malignancies in a tumor-suppressor syndrome. Systemic therapy should be considered in incomplete resected plexiform neurofibromas/MPNSTs. MEK inhibitor selumetinib can be used in NF1 children ≥2 years with inoperable/symptomatic plexiform neurofibromas, while anthracycline-based treatment is the first choice for unresectable/locally advanced/metastatic MPNST. Clinical trials on other MEK1-2 inhibitors alone or in combination with mTOR inhibitors are under investigation in plexiform neurofibromas and MPNST, respectively.