Solitary Neurofibroma with Malignant Transformation: Case Report and Review Of Literature.

Solitary neurofibromas are rare tumors associated mainly with neurofibromatosis and widely described in the literature as benign. We report a case of a 55-year-old female with no history of neurofibromatosis who presented with a slow-growing, painless lump on her torso. Pathologic evaluation of the lesion after excisional biopsy revealed high mitotic activity and increased cellularity within the lesion as well as positive S-100 stain. She was diagnosed with solitary subcutaneous neurofibroma with features of malignant peripheral nerve sheath tumor transformation. To our knowledge, no other case of a solitary neurofibroma that transformed into a malignant tumor in this location was described in the literature.