Histopathologic and Immunohistochemical Analysis of Neurofibromas in a North-Western Nigerian Tertiary Hospital: A Ten-Year Retrospective Study

Background: Neurofibromas are the most common benign nerve sheath tumours occurring as solitary sporadic tumours or multiple Syndromic tumours associated with neurofibromatosis type 1(NF1). In Nigeria and West Africa, there is a paucity of literature and studies on neurofibromas. This study aims to analyse the histopathologic and immunohistochemical patterns of neurofibromas and determine the frequency, demographic and anatomic distributions.

Methodology: The study was a hospital-based retrospective study, and the study population constituted all surgical specimens submitted for histological examination to the Department of Pathology between 1^st January 2010 to 31^st December 2019 reported as neurofibroma. Records were retrieved from the archives and subjected to histopathologic and immunohistochemical analysis following standard protocols. Collated data was analysed, slides were reviewed, and results were presented in frequency distribution tables and statistical charts.

Results: A total of 125 cases were seen constituting 8.3% of all soft tissue tumours seen. Neurofibromas were more prevalent in females with a male-to-female ratio of 1:1.15. The age ranged between 2-70 years with a mean age of 25.38 years and the highest frequency of occurrence was in the second decade of life. The most frequent anatomic site of occurrence was the head and neck region. Most of the tumours 103 (82.4%) were sporadic while 22(17.6%) were Syndromic and associated with NF1. A malignant transformation of a pre-existing neurofibroma in an NF1 patient was seen. The most common histologic variant seen was the conventional variant. Ninety percent of these tumours showed SOX10 immunopositivity, 91% showed S100 immunopositivity and 95% showed CD34 immunopositivity. Calretinin expression was low showing 16%. No hot spots labeling index seen with Ki67 antibody.

Conclusion: Neurofibromas are more common in females in our environment and the most frequent anatomic site of involvement is the head and neck region.