• adnexal neoplasm;
  • cutaneous;
  • dermatopathology;
  • DNA repair;
  • pathology

Borderline sebaceous neoplasms are rare tumors that can be challenging to diagnose because of their admixture of histopathologic features. Most such tumors have been described in patients with Muir-Torre syndrome (MTS). We report the case of an immunosuppressed, 82-year-old African-American woman without MTS who developed a rapidly growing lesion on the left cheek. Histopathology revealed a borderline sebaceous neoplasm with predominant features of sebaceous adenoma and with focal features raising concern for the possibility of an evolving, well-differentiated, low-grade sebaceous carcinoma with a high mitotic index. In the setting of immunosuppression, borderline sebaceous neoplasms may occur outside of MTS; careful evaluation and conservative treatment are recommended in managing such tumors.