ICD-10 code for Merkel cell carcinoma

The ICD-10-CM code for Merkel cell carcinoma is C4A.9 (Merkel cell carcinoma, unspecified). The official index lists 23 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on C4A.9.

Within C4A, choose C4A.9 (unspecified) only when documentation doesn't support a more specific option: of lip (C4A.0), of eyelid, including canthus (C4A.1), of ear and external auricular canal (C4A.2), of other and unspecified parts of face (C4A.3), of scalp and neck (C4A.4), of trunk (C4A.5), of upper limb, including shoulder (C4A.6), of lower limb, including hip (C4A.7) and 1 more.

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 595 (Major Skin Disorders with MCC, relative weight 2.0239) and DRG 596 (Major Skin Disorders without MCC, relative weight 1.1071), in MDC 09 (Diseases and Disorders of the Skin, Subcutaneous Tissue and Breast), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.