Sebaceous nevus is a congenital hamartoma described by Jadassohn in 1895, noting the possibility of developing epithelial neoplasia on the nevus sebaceous of Jadassohn (NSJ).
A clinicopathological study of 118 cases of nevus sebaceous of Jadassohn was made. Out of all the 118 patients, 7 patients (5.9%), 3 men and 4 women aged between 28 and 46 years, presented tumors on the NSJ, one patient having developed 4 tumors on the same NSJ.
Histopathologic examination of all these tumors revealed 7 trichoblastoma 4 of which were found on a single person, 2 syringocystadenoma papilliferum and one basal cell carcinoma.
Studies have shown that malignancies on NSJ occur at an adult age. These are usually benign epithelial cancers, the most common being the syringocystadenoma papilliferum, trichoblastoma and tricholeiomyoma. Malignant epithelial neoplasia occurred on NSJ are rare, the most commonly are the basal cell carcinoma.