BACKGROUND: Although various benign and malignant tumors can arise in nevus sebaceus (NS), the demographic and clinicopathological features of the secondary tumors vary among different published reports. The aim of this study was to obtain a better understanding of the features of tumors secondary to NS.
METHODS: A multicenter study was performed by reviewing patients diagnosed with NS from the Dermatology Department of the First Affiliated Hospital of Chongqing Medical University and Qijiang Hospital of the First Affiliated Hospital of Chongqing Medical University from 2010 to 2022. A literature review of case series of secondary tumors arising in NS was also conducted.
RESULTS: We retrospectively analyzed the literature on tumors secondary to NS published since 2000, with a total of 443 cases, and carefully studied cases of tumors arising in NS from multiple centers since 2010, with a total of 54 cases. There were 497 cases in this study; 90.3% were benign tumors (n = 449), and the rest were malignant tumors (9.7%, n = 48). Syringocystadenoma papilliferum was the most common benign tumor, followed by trichoblastoma and trichilemmoma. Basal cell carcinoma was the most common secondary malignant tumor to NS, followed by squamous cell carcinoma. Two of these cases developed metastasis. Secondary malignancies developed at an earlier age in Caucasians than in Hispanics and Asians.
CONCLUSIONS: The present study is the largest analysis of tumors secondary to NS. Racial differences were seen in secondary tumors to NS and may contribute to healthcare disparities between races.

Nevus sebaceus is frequently associated with the development of secondary neoplasms. Incidences of malignant transformation vary among different reports and few data is available regarding Asian populations. We aimed to determine the characteristics of secondary tumors developing from nevus sebaceus in a Taiwanese population and to review the published work. Patients with clinically and histologically confirmed nevus sebaceus were identified from 1992 to 2012 in a medical center. Among the 450 cases of nevus sebaceus, 38 secondary neoplasms were noted, accounting for 8.5% of all cases. Benign tumors represented more than 80% of all tumors. Syringocystadenoma papilliferum (2.7%) was the most common benign tumor, followed by trichoblastoma (1.6%) and trichilemmoma (1.6%) whereas basal cell carcinoma (0.9%) was the most frequent malignant tumor on nevus sebaceus and its clinical features were not typical. All the malignant tumors on nevus sebaceus were noted only in adulthood and the mean age of those with basal cell carcinoma was significantly older than that of trichoblastoma (P = 0.028). Our study concludes that malignant transformation is rare in nevus sebaceus and occurs uniquely in adulthood. On the basis of the findings, prophylactic excision of nevus sebaceus can be elective during childhood but is strongly advocated at puberty due to the increased risk of malignant transformation with time.

BACKGROUND: The preferential occurrence of certain skin neoplasms on the scalp of children raises concerns from their parents and warrants special diagnostic and therapeutic approaches.
OBJECTIVE: To explore the demographic and clinical characteristics of scalp neoplasms in the pediatric population, with attention to malignant tumors and systemic syndromes.
METHODS: Scalp neoplasms in patients aged 12 years or younger were retrospectively collected in 1990-2010 from two tertiary referral centers in Taiwan.
RESULTS: A total of 267 scalp neoplasms in 265 pediatric patients were recruited. Among the 209 neoplasms with a histopathological diagnosis, nevus sebaceus was the most common (67.9%), followed by melanocytic nevus (6.2%) and juvenile xanthogranuloma (6.2%). Most of the scalp neoplasms (77.9%) were seen at birth or before 1 month of age. Infantile hemangioma was clinically diagnosed without histology in 41.4% of cases. Malignant scalp tumors were identified in two patients (0.95%), with one basal cell carcinoma and one precursor B-cell lymphoblastic lymphoma, respectively. Scalp neoplasms in association with systemic syndromes were found in two cases. One had neurofibromatosis type I with juvenile xanthogranuloma and the other basal cell nevus syndrome with basal cell carcinoma.
CONCLUSIONS: Most pediatric scalp neoplasms in our study were hamartomas or teratomas. Malignant scalp tumors and malignant transformation of nevus sebaceus were rare. A detailed medical history taking and complete physical examinations are needed to exclude possible associations with systemic syndromes or malignancies.

BACKGROUND: Nevus sebaceus is commonly associated with the development of secondary neoplasms. Data on the frequency of malignant tumors vary considerably in published reports.
OBJECTIVE: We sought to analyze the distribution of secondary neoplasm in nevus sebaceus.
METHODS: A retrospective analysis of all cases of nevus sebaceus diagnosed at the Ackerman Academy of Dermatopathology from 1999 to 2012 was conducted.
RESULTS: A total of 706 patients (707 specimens) were included in the study. Trichoblastoma was the most frequent benign tumor (n = 52, 7.4%) followed by syringocystadenoma papilliferum (n = 33, 5.2%). Malignant tumors were present in 2.5% of the specimens with basal cell carcinoma being the most common (n = 8, 1.1%) followed by squamous cell carcinoma (n = 4, 0.57%). The incidence of secondary neoplasms was statistically related to age and anatomic site (P < .05). Almost all malignant tumors were seen in adults.
CONCLUSIONS: Some of our cases were referred for second opinion and there may be a bias in our data toward unusual secondary neoplasms.
CONCLUSIONS: Our study confirms that most of the secondary neoplasms arising in association with nevus sebaceus are benign. As no malignant tumors were seen in children, we believe it is reasonable to delay surgical management until adolescence.