[Exclusive nodular plexiform neurofibroma. An unusual case of neurofibromatosis type 1]

Type 1 neurofibromatous tumours (NF) are benign skin tumours which include cutaneous, subcutaneous and plexiform neurofibromas. Plexiform neurofibromas are either diffuse or nodular, the latter form being much more frequent.

We observed a particular form of neurofibroma in an 18-year-old patient who developed large deep subcutaneous which histology examination revealed to be exclusively nodular plexiform neurofibromas. The patient also had 6 café au lait spots leading to the diagnosis of sporadic NF 1. He did not have acoustic neuronoma, schwannoma or posterior cataract, eliminating NF 2.

In NF 1, subcutaneous neurofibromas develop in 5 p. 100 of the patients. These lesions are termed nodular plexiform neurofibromas when they form long formations along nerve branches. The exclusive nature of the nodular plexiform neurofibromas in our case was exceptional. It could be hypothesized that the particular phenotype in our patient might correspond to a particular anomaly of the NF 1 gene.