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. Here we address two issues that have impeded optimal MCC management: lack of a consensus staging system and lack of unique diagnostic codes for MCC. Five conflicting systems currently used to stage MCC will be replaced by one system in 2010 that will diminish confusion about prognosis and management among physicians and patients. The diagnostic bundling of MCC with numerous less aggressive skin cancers leads to care refusals by insurance and an inability to track MCC care costs. Worldwide adoption in 2009 of specific diagnostic codes for MCC will also improve 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 (table 3). The introduction of these specific codes will facilitate MCC patients in obtaining insurance approval for the appropriate treatment, help track MCC-associated costs and aid researchers in identifying and following MCC patients.

Answer 1:  Currently the index includes the sites of genital and buttock to code 209.36: Merkel cell carcinoma of other sites. We also include "specified site not elsewhere classified" to this code (209.36) in case a site would be documented that is not specifically in the index.

Question 2: How does one code MCC recurrence? Would one have to list both prior history along with code..for the current lesion ?

Answer 2:  If the recurrence happened after treatment had ended and the patient was in the history phase, then it would be coded using a Chapter 2-Neoplasms code for the new malignancy (even if it is recurring at the site of the previous malignancy) AND ALSO code V10.91 to show that there was a history.

Question 3: At what point during treatment of a patient diagnosed with MCC would we code the patient visit as prior history of MCC?

Answer 3:  There is no cut off time. In the past, people have used 5 years as the cut off but that is no longer applicable since treatments are much more effective now. The ICD-9-CM guidelines for coding malignancy state:

"When a primary malignancy has been previously excised or eradicated from its site and there is no further treatment directed to that site and there is no evidence of any existing primary malignancy, a code from category V10: Personal history of malignant neoplasm, should be used to indicate the former site of the malignancy."

The intent of the history codes (in the cases of history of MCC you would use V10.91) is to indicate that the condition no longer exists and
is not receiving any treatment, but that has the potential for recurrence, and therefore may require continued monitoring."