Partial unilateral lentiginosis is mosaic neurofibromatosis type 1 or not?

Partial unilateral lentiginosis (PUL) is a rare pigmentation disorder characterized by numerous lentigines with sharp margins in the midline in one or more dermatomes. Its segmental pattern suggests that this presentation accompanied by café-au-lait spots, Lisch nodule or neurofibromas has a close relationship with mosaic neurofibromatosis type 1 or segmental neurofibromatosis (NF) in particular. In a group of 16 patients with PUL, who presented at the dermatology outpatient clinic between 1998 and 2015, an examination was made of consanguineous marriage in the family history, the presence of a similar lesion or NF in first-degree relatives, neurofibroma in the physical examination, the involvement pattern, axillary/inguinal freckling and the presence and number of café-au-lait spots. The ophthalmological examination investigated Lisch nodule and optic glioma. The skeletal system was examined for NF involvement. Of 16 patients, 13 (81.2%) were female and three (18.8%) were male with a mean age of 31.19 years (range, 15-48). There was no family history of PUL in any case. Consanguineous marriage was absent in 15 patients (93.8%). While there were accompanying café-au-lait spots in three patients (18.8%). Lisch nodule was an accompanying finding in three patients (18.8%). Axillary freckling was detected in four (25%) patients. Neurofibroma was found in only one patient. Although café-au-lait spots, axillary freckling, neurofibroma and Lisch nodule were present in a small number of the patients, the presence of the findings may be considered to be specific to NF suggests that PUL is a variant of mosaic NF-1. Genetic studies will help to further elucidate this subject.