Plexiform neurofibroma considered pathognomonic for neurofibromatosis type 1, therefore patient sent to undergo genetic testing.

Diagnostic criteria  - The hallmarks of NF1 are the multiple café-au-lait spots (CALS) and associated cutaneous neurofibromas. The diagnostic criteria developed by the NIH Consensus Conference in 1987 and updated in 1997 are based upon specific clinical features of NF1. According to these criteria, at least two of the following clinical features must be present to make the diagnosis of NF1:

• Six or more café-au-lait macules >5 mm in diameter in prepubertal and >15 mm in diameter in postpubertal individuals; for each lesion, the longest diameter is measured.
• Two or more neurofibromas of any type or one plexiform neurofibroma.
• Freckling in the axillary or inguinal regions.
• Optic glioma.
• Two or more Lisch nodules (iris hamartomas).
• A distinctive bony lesion such as sphenoid dysplasia or thinning of the long bone cortex with or without pseudoarthrosis.
• A first-degree relative (parent, sibling, or offspring) with NF1 based upon the above criteria.

Special thanks to Dr. David Mamunts, "Davidyants Laboratories" Yerevan, Armenia for contributing histopathology report.