How can Bowen's disease be differentiated from squamous cell carcinoma?

Bowen's disease, a form of squamous cell carcinoma in situ, is characterized by atypical squamous cells that are confined to the epidermis and do not invade the underlying dermis. The presence of an intact basement membrane is a crucial factor in distinguishing Bowen's disease from invasive squamous cell carcinoma. Invasive squamous cell carcinoma demonstrates cellular infiltration beyond the basement membrane, indicating a loss of this structural boundary. Thus, histological examination for basement membrane confinement is vital for the diagnosis. Identifying whether the atypical cells only occupy the epidermal layer helps confirm that the condition is still confined to its in situ state, characteristic of Bowen's disease.