Overall morphology | Similar to sebaceous adenoma, but with more basaloid component | Similar to classical BCC, but with a component of sebaceous differentiation |
Main components | Aggregates of basaloid germinative cells admixed with single units or clusters of mature vacuolated sebocytes | Aggregate of follicular germinative basaloid cells |
Architectural pattern | Benign | Malignant |
Cytological features | Monomorphous basaloid cells, with small oval nuclei and non-prominent nucleoli | Pleomorphic basaloid cells, with slightly elongated nuclei |
Mitotic activity | Mild/absent | Brisk |
Sebaceous differentiation | Prominent | Focal and associated with apocrine differentiation in many cases |
Peripheral palisading | Usually absent | Present |
Artefactual clefting | Absent | Often present |
Basaloid tumour necrosis | Rare | Frequent |
Other associated features | Sebaceous duct-like structures, rare squamous differentiation, and dense eosinophilic dermal sclerosis | Sebaceous duct-like structures, individual cell necrosis, keratinization and mucinous stroma |