Clinicopathological study of neurofibromatosis type 1: an experience in Nigeria

BACKGROUND: Neurofibromatosis type 1 (NF1) is the commonest single gene autosomal dominant disorder, and its diagnosis is usually composed of a set of clinical criteria. Histological examination of skin lesions is often neglected. This study was designed to evaluate the clinical and pathologic pattern of NF1 among Nigerians and to emphasize the place of histological examination. METHODS: A retrospective case study of 98 clinically diagnosed NF1 patients whose dermal mass lesions (neurofibromas) were excised and processed for histological diagnosis over a period of 22 years (1980-2001) at the University of Ilorin Teaching Hospital (UITH), Ilorin, Nigeria. RESULTS: There were 98 patients: 60 males and 38 females (ratio 3 : 2) aged 1-99 (mean +/- S.D. = 3.4 +/- 1.7) years. All patients had neurofibromas, which were benign in 95 patients (96.9%) and malignant in three (3.1%) patients, while 94 (96%) patients had cafe-au-lait spots. Benign neurofibromas were clinically cutaneous 50 (51%)], subcutaneous 37 (37.8%)] and plexiform 8 (8.2%)]. Site distribution of the neurofibromas included the extremities (50%), trunk (20.4%), head and neck (19.4%), and multiple sites (10.2%). Three patients presenting with neurofibosarcomas were aged 4, 23 and 27 years, respectively. Their deaths were responsible for the mortality rate of 3.1% recorded in this study. CONCLUSIONS: In our setting, NF1 is more common among males, with the highest density of neurofibromas covering the extremities.