52-year-old man with pink-yellow papules   

Findings and diagnosis


Microscopic exam showed aggregations of immature sebocytes emanating from the undersurface of the epidermis and extending into the dermis, surrounded by sheets of atypical basaloid epithelial cells with increased mitotic figures.

Inmunostains showed abnormal (deficient) staining patterns for mismatch repair proteins PMS2 and MLH1. There is a normal (intact) staining pattern for mismatch repair proteins MSH2 and MSH6.

Differential diagnosis

  • Benign sebaceous neoplasms (e.g., sebaceous adenoma)
  • Basal cell carcinoma
  • Inflammatory lesions (when periocular, e.g., chalazion, blepharoconjunctivitis, or keratoconjunctivitis)
  • Squamous cell carcinoma
  • Merkel cell carcinoma
  • Sebaceous carcinoma

 Diagnosis: Sebaceous carcinoma