Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of In situ
Medically reviewed by Min Clinic Staff | Updated: January 2026
In situ: In the normal location. An in situ tumor is one that is confined to its site of origin and has not invaded neighboring tissue or gone elsewhere in the body. For example, squamous cell carcinoma in situ is an early stage of skin cancer.