Pathology of Neurofibroma; Types of Neurofibroma, Histopathological Features скачать в хорошем качестве

Pathology of Neurofibroma; Types of Neurofibroma, Histopathological Features

Neurofibroma is a benign peripheral nerve sheath tumor that arises from a mixture of cell types, including Schwann cells, fibroblasts, perineurial cells, and mast cells, embedded within a collagenous and myxoid stroma. It’s often associated with Neurofibromatosis type 1 (NF1) but can also occur sporadically. 🔬 Histopathological Features Unencapsulated lesion: Unlike schwannomas, neurofibromas lack a capsule and infiltrate surrounding tissue3. Spindle-shaped cells: Cells have wavy, serpentine nuclei and pointed ends, arranged in a loose, disorganized pattern. Stroma: Varies from myxoid to collagenous, sometimes described as “shredded carrot” appearance. Mast cells: Frequently present and easily identifiable. Axons: Interspersed within the tumor, which can be highlighted using neurofilament immunostaining. 🧪 Immunohistochemistry Marker Expression Notes S100 Positive Indicates Schwann cell origin3 CD34 Positive (stromal) Highlights fibroblastic component EMA Negative (except in plexiform subtype) Helps differentiate from perineurioma 🧬 Subtypes Localized Neurofibroma Most common; solitary, superficial lesion. Typically occurs in young adults without NF1. Plexiform Neurofibroma Involves multiple nerve fascicles in a tortuous, “bag of worms” pattern. Virtually diagnostic of NF1 and carries a risk of malignant transformation. Diffuse Neurofibroma Poorly circumscribed; causes plaque-like thickening of skin. Often seen in the head and neck region of children and young adults. 🧠 Genetic Basis Caused by biallelic inactivation of the NF1 gene, which encodes neurofibromin, a tumor suppressor involved in RAS pathway regulation. In sporadic cases, only lesional cells carry the mutation; in NF1, it’s a germline defect. #Pathology #Neurofibroma