Table 6 Useful histological features for distinguishing between sebaceoma and basal cell carcinoma with sebaceous differentiation.

Feature	Sebaceoma	BCC with sebaceous differentiation
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

BCC, basal cell carcinoma.