Bowen’s disease, sometimes referred to as squamous cell carcinoma in situ, is a form of squamous cell carcinoma that appears as a red, scaly, and irregular plaque that slowly enlarges as the cancerous cells grow laterally. The phrase in situ means “in its original place” and is used to differentiate this form of cancer from invasive squamous cell carcinoma – a more serious form which carries a higher risk of metastasis.