In-transit metastasis is a group of tumour cells found within the skin or soft tissue at least 2 cm from the original tumour. The word ‘in-transit’ is used because the tumour cells are found in between the original tumour and the first lymph nodes that drain that area of the body.
Pathologists typically use the term in-transit metastasis when describing the movement of tumour cells in a type of skin cancer called melanoma. In melanoma, pathologists look for in-transit metastases to determine the pathologic cancer stage (pTNM).