Table 6

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

FeatureSebaceomaBCC with sebaceous differentiation
BCC, basal cell carcinoma.
Overall morphologySimilar to sebaceous adenoma, but with more basaloid componentSimilar to classical BCC, but with a component of sebaceous differentiation
Main componentsAggregates of basaloid germinative cells admixed with single units or clusters of mature vacuolated sebocytesAggregate of follicular germinative basaloid cells
Architectural patternBenignMalignant
Cytological featuresMonomorphous basaloid cells, with small oval nuclei and non-prominent nucleoliPleomorphic basaloid cells, with slightly elongated nuclei
Mitotic activityMild/absentBrisk
Sebaceous differentiationProminentFocal and associated with apocrine differentiation in many cases
Peripheral palisadingUsually absentPresent
Artefactual cleftingAbsentOften present
Basaloid tumour necrosisRareFrequent
Other associated featuresSebaceous duct-like structures, rare squamous differentiation, and dense eosinophilic dermal sclerosisSebaceous duct-like structures, individual cell necrosis, keratinization and mucinous stroma