Prevalence and clinicopathological characteristics of lipomatous neurofibromas in neurofibromatosis 1: An investigation of 229 cutaneous neurofibromas and a systematic review of the literature

• Published in: Journal of cutaneous pathology Vol. 45; no. 10; pp. 743 - 753
• Main Authors: Rozza‐de‐Menezes, Rafaela Elvira, Brum, Carolina de Almeida Ito, Gaglionone, Nicolle Cavalcante, de Sousa Almeida, Lilian Machado, Andrade‐Losso, Raquel Machado, Paiva, Brenda Vasconcelos Barboza, Faveret, Pedro Leonardo Sanches, da Silva, André Vallejo, Siqueira, Orlando Hiroshi Kiono, Riccardi, Vincent M., Cunha, Karin Soares
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-10-2018; Wiley Subscription Services, Inc
• Subjects: Adipocytes; Adipocytes - pathology; Adolescent; Adult; Aged; Female; Genetic disorders; Giant cells; Humans; Investigations; Leptin; Lipid metabolism; Literature reviews; Male; Middle Aged; neurofibroma; Neurofibroma - epidemiology; Neurofibroma - pathology; Neurofibromatosis; neurofibromatosis 1; Neurofibromatosis 1 - complications; Neurofibromatosis 1 - pathology; Neurological disorders; Pathogenesis; Prevalence; Recklinghausen's disease; Reviews; Skin Neoplasms - epidemiology; Skin Neoplasms - pathology; Tumors; Young Adult; neurofibroma; adipocytes; leptin; neurofibromatosis 1
• ISSN: 0303-6987; 1600-0560
• DOI: 10.1111/cup.13315

Background
Lipomatous neurofibroma (Lnf) is a histopathological variant with adipocytes noted among cells of cutaneous neurofibromas. We aimed to investigate the prevalence and clinicopathological features of Lnfs of neurofibromatosis 1 (NF1)‐associated cutaneous neurofibromas and to review the literature systematically. We also evaluated the expression of leptin (a hormone involved in lipid metabolism) in neurofibromas to better understand the pathogenesis of Lnfs.
Methods
A prospective histologic study was conducted on 229 cutaneous neurofibromas from 85 NF1 individuals. Leptin expression was immunohistochemically evaluated in 111 cutaneous neurofibromas. To systematically review the literature, two authors independently performed literature searches without year restriction.
Results
Forty (17.5%) neurofibromas were lipomatous. Lnfs were significantly larger lesions and associated with females. Eighteen (7.9%) of all neurofibromas had multinucleated floret‐like giant cells, and these were associated with Lnfs. All neurofibromas expressed leptin. We systematically reviewed 13 articles. Three large studies investigated Lnfs mainly in sporadic neurofibromas and suggested that 0.3% to 8.0% of tumors (NF1 and sporadic) are Lnfs.
Conclusion
In NF1, Lnfs are common, mainly in larger tumors and women. All cutaneous NF1‐neurofibromas express leptin. It is unknown if the expression of leptin accounts for the lipomatous variant, but it may have a role in the pathogenesis of cutaneous neurofibroma.