Diffuse cutaneous neurofibroma

Last revised by Frank Gaillard on 26 Feb 2022

Diffuse cutaneous neurofibromas are a rare subtype of neurofibroma similar to plexiform neurofibromas.

There are variable uses and some confusion about the distinction between plexiform neurofibroma and diffuse cutaneous neurofibroma, with some sources not clearly distinguishing between the two. Generally, plexiform neurofibromas are deeper lesions affecting nerves and plexus. The two may, however, co-exist 5

Importantly it appears that diffuse cutaneous neurofibromas may not be as closely associated with neurofibromatosis type 1, nor have the same risk of malignant transformation 1-6. The distinction is thus important and they are recognized as separate entities in the WHO classification of CNS tumors and the WHO classification soft tissue tumors 7.

Diffuse neurofibromas mainly affect children and young adults 1

Unlike plexiform neurofibromas, diffuse cutaneous neurofibromas are not strongly associated with neurofibromatosis type 1 (NF1), with only 10% of affected individuals having the condition 1,4,6.  

These tumors most frequently present with overgrowth of the subcutaneous tissues typically of the head and neck, trunk, and extremities1

Diffuse cutaneous neurofibromatosis causes plaque-like elevation of the skin with thickening of the entire subcutis with a variety of macroscopic appearances ranging from flat to pedunculated but without the focal nodular masses characteristic of localized cutaneous forms 1,3,4.

In addition to many of the features seen in other forms of neurofibroma, diffuse cutaneous neurofibromas have distinctive pseudomeissnerian bodies, which are rounded layered structures also found in plexiform neurofibromas 7

Diffuse cutaneous neurofibromas usually have fairly non-specific signal intensity 1

  • T1: iso- to hypointense to skeletal muscle
  • T1 C+: usually vivid contrast enhancement
  • T2: hyperintense to skeletal muscle

Unlike plexiform neurofibromas, malignant transformation is uncommon 1,4,7.

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