C26.9Malignant neoplasm of ill-defined sites within the digestive system

C26.9 is the ICD-10-CM diagnosis code for malignant neoplasm of ill-defined sites within the digestive system. It belongs to category C26 (malignant neoplasm of other and ill-defined digestive organs), block C15-C26 (malignant neoplasms of digestive organs) and chapter 2 (neoplasms). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within C26 (malignant neoplasm of other and ill-defined digestive organs), C26.9 is specifically for malignant neoplasm of ill-defined sites within the digestive system. Related codes cover intestinal tract, part unspecified (C26.0) and spleen (C26.1).

Don't report C26.9 together with the conditions in its Excludes1 note: malignant neoplasm of abdominal NOS (C76.2) and malignant neoplasm of intra-abdominal NOS (C76.2).

It is not a CC or MCC, so as a secondary diagnosis it doesn't change the MS-DRG severity level.

In MS-DRG v44.0, it is part of the grouping logic for DRG 374 (Digestive Malignancy with MCC, relative weight 2.1109), DRG 375 (Digestive Malignancy with CC, relative weight 1.1838) and DRG 376 (Digestive Malignancy without CC/MCC, relative weight 0.8929), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 159.8 (malignant neoplasm of other sites of digestive system and intra-abdominal organs) and 159.9 (malignant neoplasm of ill-defined sites within the digestive organs and peritoneum).