Co-Occurrence of neurofibromatosis-1 with urticaria pigmentosa: A Coincidental association?

Abstract

Neurofibromatosis-1 (NF-1) is a neuroectodermal abnormality characterized by multiple neurofibromas, café-au-lait macules, axillary freckling, and Lisch nodules. Urticaria pigmentosa (UP) is a maculopapular cutaneous mastocytosis due to mast cell hyperplasia. We report a case of NF-1 associated with UP. A 19-year-old male presented with multiple neurofibromas, café-au-lait macules, axillary freckling, and Lisch nodules. He also had UP lesions with positive Darier's sign. A clinical diagnosis of NF-1 with UP was made and confirmed histopathologically. Mastocytosis exhibits mast cell hyperplasia due to C-kit gene mutation. Mast cell mediatiors directly contribute to neurofibroma growth. C-kit receptor abnormality is implicated in the formation of neurofibromas as well as in UP. With possible interconnected underlying pathology of mast cell hyperplasia and increased mast cell mediators in both UP and NF-1, a possible association of NF and UP beyond simple coincidence should be considered.