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Coding regressing melanoma has been an issue as registrars may not realize it is a reportable histology. Hence, H4 was written to reinforce correct histology. A note will be added to H1 instructing registrars to continue thru rules when the diagnosis is regressing melanoma.

For cases diagnosed 2007-2014:

Apply MP/H Melanoma Histology Coding rule H5 and code the histologic type of the melanoma.

Code example 1 as 8743 [Superficial spreading melanoma].

Code example 2 as 8742 [Lentigo maligna melanoma].

For cases diagnosed 2007 or later:

Code malignant melanoma in situ with regression to 8720/2 [Melanoma in situ].

Code the histology according to the histologic type specified in the pathology report final diagnosis. Code the behavior as specified in the pathology report. Regression does not affect the coding of histology or behavior. See Melanoma Histology Coding rule H5. See 2007 SEER manual instructions for coding behavior, page 84.

Tumoral melanosis (TM) alone is not reportable. It is not listed in ICD-O-3. TM can be associated with a regressed melanoma, but it can also occur with other cutaneous tumors. The case is reportable if there is a diagnosis of melanoma.

Compound nevus with severe atypia is not reportable unless also stated to be malignant melanoma or melanoma in situ.

This answer was provided in the context of CSv1 coding guidelines. The response may not be used after your registry database has been converted to CSv2.

For tumors diagnosed prior to 2007:

Regression does not affect CS staging for cutaneous melanoma. "Malignant melanoma, regressing" [8723] is coded only when it is the final diagnosis. Do not use code 8723 for the examples above.

According to our pathologist consultant:

Melanoma can occasionally undergo "spontaneous" regression -- the tumor can become smaller, and in some cases even disappear. This phenomenon is likely due to an increased immune response on the part of the "host" (person with the melanoma). This is noted occasionally in patients with metastatic disease which gets smaller, or even disappears. We think this is also what has happened in patients who get diagnosed with metastatic melanoma, say in a lymph node, but have no primary tumor, though sometimes give a history of a skin lesion which came and then went away, or a skin lesion which was not submitted for pathological examination. In addition, we (pathologists) occasionally see biopsies which have melanoma as well as the presence of the immune reaction to it, and once in a while, the immune reaction with little or no evidence of residual melanoma.

The College of American Pathologists says that regression of 75% or more of the melanoma carries an adverse prognosis.

For tumors diagnosed 2007 or later, refer to the MP/H rules. If there are still questions about how this type of tumor should be coded, submit a new question to SINQ and include the difficulties you are encountering in applying the MP/H rules.