Histologic margin involvement by cutaneous basal cell carcinoma stroma: a retrospective cohort study for residual or...

The clinical significance of histologic margin involvement by basal cell carcinoma (BCC)-associated stroma remains uncertain. This study aimed to determine the incidence of residual BCC in immediate re-excision specimens or clinical recurrence in cases managed without re-excision.

Fifty-eight cases of BCC with stromal margin involvement diagnosed between 2016 and 2020 were retrospectively reviewed. Fifty cases underwent immediate surgical re-excision, and eight were managed with clinical observation for at least two years. Tumors were classified by histologic subtype, and stromal margin involvement was categorized as peripheral, deep, or both. Residual carcinoma on re-excision or clinical recurrence within two years was recorded.

Residual carcinoma was identified in 8% of re-excised cases (4/50) and occurred exclusively in tumors with a superficial component, including three pure superficial BCCs and one mixed superficial-nodular BCC; all residual tumors were of superficial subtype. No residual carcinoma was observed among 23 nodular or infiltrative BCCs that underwent re-excision. None of the eight cases managed with observation (1 superficial, 2 mixed superficial-nodular, 5 nodular) demonstrated clinical recurrence within two years. Overall, residual or recurrent disease occurred in 7% of cases (4/58). The distribution of adverse outcomes differed significantly by histologic subtype.

Stromal margin involvement in non-superficial BCCs is rarely associated with residual or recurrent carcinoma. Adverse outcomes were confined to tumors containing a superficial component, highlighting biologic heterogeneity among BCC subtypes. These findings suggest that routine re-excision may be unnecessary for stromal-margin-positive BCCs lacking a superficial component and support more selective, subtype-informed management.