Plexiform Neurofibroma Without Neurofibromatosis Type 1.

Area of Science:

• Oncology
• Dermatology
• Genetics

Background:

• Plexiform neurofibroma (PNF) is a benign nerve sheath tumor characterized by a reticular growth pattern involving multiple nerve fascicles.
• PNF is most commonly associated with neurofibromatosis type-1 (NF-1), affecting up to 30% of patients, and can also occur in schwannomatosis and neurofibromatosis type-2 (NF-2).
• While NF-1 predisposes individuals to benign and malignant tumors, isolated cutaneous PNFs do not typically transform into malignant peripheral nerve sheath tumors.

Observation:

• A case report of an isolated plexiform neurofibroma in a 16-year-old girl with no history or clinical signs of NF-1 or NF-2.
• The patient presented with a slow-growing, asymptomatic, 1.8x1.6 cm exophytic nodule on her right flank, initially suspected to be a nevus.
• Histopathological examination revealed a spindle-cell proliferation consistent with PNF, with S-100 positive cells and myxoid stroma.

Findings:

• The diagnosis of an isolated plexiform neurofibroma, unassociated with NF-1 or NF-2, is exceptionally rare.
• Surgical excision was performed for cosmetic reasons, with successful healing and no signs of recurrence or associated syndromes.
• Literature review confirms the rarity of isolated PNFs, with only a few cases reported globally, occurring in various locations and age groups.

Implications:

• This case underscores the importance of considering isolated PNF in the differential diagnosis of cutaneous tumors, even in the absence of typical NF-1 stigmata.
• Surgical intervention remains the gold standard treatment for symptomatic or aesthetically concerning isolated PNFs.
• Further research into the genetic and molecular underpinnings of isolated PNFs may reveal novel therapeutic targets, with ongoing evaluation of agents like selumetinib and mTOR inhibitors.