Merkel cell carcinoma, unspecified

This code represents a malignant neoplasm of neuroendocrine cells in the skin, specifically Merkel cell carcinoma, when the primary site is not specified. It is a rare and aggressive form of skin cancer that often presents as a rapidly growing, firm, painless nodule.

Use this code when the medical record clearly documents a diagnosis of Merkel cell carcinoma, but the specific anatomical location or primary site of the tumor is not identified. This code is appropriate when the provider's documentation lacks the specificity needed to assign a more precise anatomical site code (e.g., C4A.0-C4A.8).

• Avoid using this code if the documentation specifies the primary anatomical site of the Merkel cell carcinoma; instead, select the appropriate site-specific code (C4A.0-C4A.8).
• Always query the provider for clarification on the primary site if "unspecified" is documented, to allow for more precise coding.
• This code is for the malignant neoplasm itself, not for benign or uncertain skin lesions.