| C4A | Merkel cell carcinoma | NON-BILLABLE CODE |
| C4A.0 | Merkel cell carcinoma of lip | BILLABLE CODE |
| C4A.1 | Merkel cell carcinoma of eyelid, including canthus | NON-BILLABLE CODE |
| C4A.10 | Merkel cell carcinoma of unspecified eyelid, including canthus | BILLABLE CODE |
| C4A.11 | Merkel cell carcinoma of right eyelid, including canthus | NON-BILLABLE CODE |
| C4A.111 | Merkel cell carcinoma of right upper eyelid, including canthus | BILLABLE CODE |
| C4A.112 | Merkel cell carcinoma of right lower eyelid, including canthus | BILLABLE CODE |
| C4A.12 | Merkel cell carcinoma of left eyelid, including canthus | NON-BILLABLE CODE |
| C4A.121 | Merkel cell carcinoma of left upper eyelid, including canthus | BILLABLE CODE |
| C4A.122 | Merkel cell carcinoma of left lower eyelid, including canthus | BILLABLE CODE |
| C4A.2 | Merkel cell carcinoma of ear and external auricular canal | NON-BILLABLE CODE |
| C4A.20 | Merkel cell carcinoma of unspecified ear and external auricular canal | BILLABLE CODE |
| C4A.21 | Merkel cell carcinoma of right ear and external auricular canal | BILLABLE CODE |
| C4A.22 | Merkel cell carcinoma of left ear and external auricular canal | BILLABLE CODE |
| C4A.3 | Merkel cell carcinoma of other and unspecified parts of face | NON-BILLABLE CODE |
| C4A.30 | Merkel cell carcinoma of unspecified part of face | BILLABLE CODE |
| C4A.31 | Merkel cell carcinoma of nose | BILLABLE CODE |
| C4A.39 | Merkel cell carcinoma of other parts of face | BILLABLE CODE |
| C4A.4 | Merkel cell carcinoma of scalp and neck | BILLABLE CODE |
| C4A.5 | Merkel cell carcinoma of trunk | NON-BILLABLE CODE |
| C4A.52 | Merkel cell carcinoma of skin of breast | BILLABLE CODE |
| C4A.59 | Merkel cell carcinoma of other part of trunk | BILLABLE CODE |
| C4A.6 | Merkel cell carcinoma of upper limb, including shoulder | NON-BILLABLE CODE |
| C4A.60 | Merkel cell carcinoma of unspecified upper limb, including shoulder | BILLABLE CODE |
| C4A.61 | Merkel cell carcinoma of right upper limb, including shoulder | BILLABLE CODE |
| C4A.62 | Merkel cell carcinoma of left upper limb, including shoulder | BILLABLE CODE |
| C4A.7 | Merkel cell carcinoma of lower limb, including hip | NON-BILLABLE CODE |
| C4A.70 | Merkel cell carcinoma of unspecified lower limb, including hip | BILLABLE CODE |
| C4A.71 | Merkel cell carcinoma of right lower limb, including hip | BILLABLE CODE |
| C4A.72 | Merkel cell carcinoma of left lower limb, including hip | BILLABLE CODE |
| C4A.8 | Merkel cell carcinoma of overlapping sites | BILLABLE CODE |
| C4A.9 | Merkel cell carcinoma, unspecified | BILLABLE CODE |
