Drop Metastasis

 

Features of a drop metastasis:

(1) primary tumor with extension into a fluid-filled space (CSF, pleural space, peritoneal cavity, urinary tract)

(2) presence of a secondary deposit of exactly the same tumor

(3) the secondary deposit is in location dependent or downstream to the primary focus (with spread by gravity or fluid flow)

 

Examples:

(1) primary CNS tumor with small metastases around the spinal cord

(2) thymoma with posterior or inferior tumor deposit in the pleural space

(3) renal cell carcinoma with metastasis in urinary bladder

 

Exclusions:

(1) second primary

(2) other mechanism of tumor spread (hematologic, lymphatic, etc)