K63.5 vs D12.4 colon polyp
Polyps are defined as an abnormal growth of tissue projecting from a mucous membrane. They are attached by a narrow stalk. Polyps often are benign, but they can become malignant over time if not removed. Coding for polyps can be accomplished by using the Index to Diseases and Injuries confirming the code choice in the Tabular List.
According to Coding Clinic, ATE (Hyperplastic versus Adenomatous Colon Polyp) (2017 Vol 4, No 1) ICD-10-CM does not classify adenomatous (neoplastic) polyps of the colon the same as hyperplastic polyps. Code K63.5 describes a hyperplastic polyp and is the default when the type of polyp is not specified as adenomatous/neoplastic. Hyperplastic polyps, by definition, are not neoplastic, and are typically followed on a much different surveillance protocol than adenomatous polyps. Category D12, Benign neoplasm of colon, rectum, anus and anal canal, classifies neoplastic polyps according to anatomic location.
You can use code D12.4 for benign neoplasm (adenomatous polyp) of descending colon.