Gastroenterology Coding Alert

Question: What is the correct code for leiomyosarcoma (LMS) of the sigmoid colon? I have found documentation stating if the LMS has originated in an organ, then it should be coded to the site. However, the provider is insisting that it should be coded to connective tissue.

AAPC Forum Participant

Answer: Your provider is correct, in this case.

Here’s why: According to the National Cancer Institute, LMS is “a type of rare cancer that grows in the smooth muscles. The smooth muscles are in the hollow organs of the body, including the intestines, stomach, bladder … blood vessels … [and] the uterus.”

This makes LMS a soft, or connective, tissue sarcoma. Per the ICD-10-CM Alphabetic Index, LMS is coded to Neoplasm, connective tissue, malignant, which is consistent with the note in the neoplasm table that tells you to code neoplasms of connective tissue according to ‘Neoplasm, connective tissue’ and to “code to neoplasm of that site” for “sites that do not appear in this list.”

Because “Neoplasm, connective tissue, intestinal, malignant” appears on the list for code C49.4 (Malignant neoplasm of connective and soft tissue of abdomen), that is the code you should use rather than coding the neoplasm to the site, which would be C18.7 (Malignant neoplasm of sigmoid colon).