Clinicopathologic Features and Outcomes of Basal Cell Carcinoma Coexisting with Other Tumors or Precancerous Lesions: A Single-Center Analysis.

OBJECTIVE: To characterize the clinicopathologic spectrum, treatment patterns, and outcomes of basal cell carcinoma (BCC) coexisting with other tumors or precancerous lesions. METHODS: We retrospectively reviewed pathologically confirmed cases diagnosed at Peking Union Medical College Hospital between 2020 and 2025. Demographic, clinical, histopathologic, treatment, and outcome data were extracted and analyzed. RESULTS: Among 860 pathologically confirmed BCC cases, 17 met the inclusion criteria. The cohort comprised 9 women (52.9%) and 8 men (47.1%), with a mean age of 56.71 ± 21.14 years. Coexisting lesions were classified as hamartoma/nevus-associated (7 cases), keratinocytic lesion-associated (5 cases), or adnexal/cyst-associated (5 cases). Nevus sebaceus was the most frequent coexisting lesion. All lesions involved the head and neck, and 16 (94.1%) showed recent enlargement or another new change on a preexisting lesion. Nodular and superficial BCC predominated. Exploratory comparison with a contemporary head and neck BCC cohort suggested that the present cohort was characterized by younger age, more frequent scalp/frontotemporal involvement, enrichment of superficial BCC, and fewer aggressive subtypes. Most patients had favorable outcomes without recurrence or metastasis observed. CONCLUSION: BCC coexisting with other tumors or precancerous lesions has a distinct clinicopathologic profile, and often presents as recent changes in a long-standing head/neck lesion. Classification by coexisting lesion type may help integrate clinical morphology, pathology, and risk assessment.