I have small bumps under my skin, mostly on my forearm.they are cyst like and itchy. could itbe neurofibroma?

Doubt it: If you had neurofibromatosis, you should have been diagnosed at a much younger age. Neurofibromas are characteristically firm, as they are solid nerve tumors, rather than cystic structures. Itching is not a typical symptom of a neurofibroma, rather a symptom reflecting allergy or inflammation. A contact dermatitis or other skin condition sounds more likely. See your pcp or a dermatologist.