Merkel cell carcinoma (MCC) is a neuroendocrine skin cancer with a higher propensity for recurrence and metastasis than melanoma or squamous cell carcinoma. Despite aggressive behavior and the tripling of its reported incidence in the past 20 years, there is extensive confusion about how MCC should be managed. Worldwide adoption in 2009 of specific ICD diagnostic codes for MCC improved the understanding and management of this often-lethal skin cancer.
Until late 2009, MCC was coded in the ICD system as 173.x: “Other malignant neoplasm of skin” along with BCC, SCC and many other skin cancers. This sometimes impedes management of MCC patients as insurance companies use these codes to determine whether or not a test, scan or treatment is appropriate for the diagnosis in question. When a disease does not have a code that appropriately captures its management and treatment, multiple codes must be used to attempt to justify proposed therapies for insurance and billing approvals. This was certainly the case for MCC as it was grouped with BCC and other benign diagnoses that rarely require aggressive management or inpatient care.
To address this issue, a petition was made to the CDC on behalf of the Merkel cell carcinoma Multi-center Interest Group (MMIG) to create specific ICD-CM codes for MCC. The rationale for this petition included the fact that other distinctive skin cancers with potentially aggressive behavior have unique codes. These include cutaneous T cell lymphoma (CTCL) whose incidence is approximately that of MCC 25 (code 202.x) as well as malignant melanoma (172.x). In January 2009, the CDC granted 7 MCC-specific codes that became active as of October 1, 2009. The introduction of these specific codes, later followed by the updated ICD-10 codes (table 3) help MCC patients in obtaining insurance approval for the appropriate treatment, help track MCC-associated costs and aid researchers in identifying and following MCC patients.
Merkel Cell Carcinoma Description
MCC of the Face
Eyelid (including canthus)
Ear (and external auricular canal)
Face, other part
Scalp and Neck
MCC of the Limb
Upper limb (including shoulder)
Upper limb, unspecified
Upper limb, right
Upper limb, left
Lower limb (including hip)
Lower limb, unspecified
Lower limb, right
Lower limb, left
MCC of the Trunk
Anal or perianal skin
Skin of breast
Trunk, other part
Overlapping sites (eg, junction of neck and trunk)
Metastatic MCC or nodal presentation without known primary