C7B.1Secondary Merkel cell carcinoma

C7B.1 is the ICD-10-CM diagnosis code for secondary Merkel cell carcinoma. It belongs to category C7B (secondary neuroendocrine tumors), block C7B (secondary neuroendocrine tumors) 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 C7B (secondary neuroendocrine tumors), C7B.1 is specifically for secondary Merkel cell carcinoma. Related codes cover secondary carcinoid tumors (C7B.0) and other secondary neuroendocrine tumors (C7B.8).

Use an additional code to identify any functional activity.

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 826 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with MCC, relative weight 4.7581), DRG 827 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures with CC, relative weight 2.3896), DRG 828 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Major O.R. Procedures without CC/MCC, relative weight 1.6955), DRG 829 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures with CC/MCC, relative weight 3.1281), DRG 830 (Myeloproliferative Disorders or Poorly Differentiated Neoplasms with Other Procedures without CC/MCC, relative weight 1.4859), DRG 843 (Other Myeloproliferative Disorders or Poorly Differentiated Neoplastic Diagnoses with MCC, relative weight 1.9453) and 2 more, in MDC 17 (Myeloproliferative Diseases and Disorders, Poorly Differentiated Neoplasms), 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 209.75 (secondary Merkel cell carcinoma).