Merkel cell carcinoma of unsp upper limb, including shoulder

This code signifies a malignant neuroendocrine tumor of the skin, specifically Merkel cell carcinoma, located on an unspecified part of the upper limb, which includes the shoulder. It indicates an aggressive form of skin cancer originating from Merkel cells, without further specification of the exact location within the upper limb.

Use this code when documentation confirms a diagnosis of Merkel cell carcinoma affecting the upper limb or shoulder, but the precise anatomical site (e.g., arm, forearm, hand) is not specified. This code is appropriate when the pathology report confirms Merkel cell carcinoma and the physician's notes indicate an upper limb or shoulder primary site without further detail.

• Ensure the pathology report explicitly states "Merkel cell carcinoma."
• Avoid using this code if a more specific anatomical site within the upper limb (e.g., C4A.31 for right upper limb, C4A.32 for left upper limb) is documented.
• Always sequence this code as a primary diagnosis when it is the reason for the encounter, unless another condition is clearly identified as the principal diagnosis.