Question: A patient has been diagnosed with a Merkel cell tumor on the skin of his leg. What is the correct ICD-9 code for this condition? I know that a Merkel cell tumor is a stage IV neuroendocrine tumor. Someone suggested using a melanoma code, but I want to be sure that the code I-m using is correct. Wisconsin Subscriber Answer: You-ll start your coding process by looking in the ICD-9 index under Merkel cell tumor. The entry directs you to Neoplasm, by site, malignant. Under neoplasm, you-ll find 173.x (Other malignant neoplasm of skin). Don't forget: You need the fourth digit to code properly for this condition. The code you-re looking for is 173.7 (Skin of lower limb, including hip), which includes a listing for various sites including the leg.