This article describes some types of growth in plexiform neurofibroma (PNF) on magnetic resonance images (MRI). This tumor is almost exclusively associated with NF1. On MRI, the tumor is depicted as a hyperintensive area on T2-weighted images. We distinguished 3 patterns of tumor growth: first, the superficial and non-invasive tumors, that are restricted to the cutis and subcutis, only eventually having outgrowth to the muscles beneath and are slow growing. Second, the displacing PNF that develop in deeper layers of the skin or within the body. They can grow to a large extent but do not invade adjacent muscles or skin. Thirdly, the invasive type with no visible margins that cannot be resected without adjacent structures or organs. A combination of these tumors can sometimes be noted, e.g. a displacing tumorous nerve developing in a large lumpy, non-invasive PNF. These categories might be used as a current guideline for medical advice, surgical treatment planning and medication trials.
