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SEER Inquiry System - Report
Produced: 01/21/2026 8:53 AM
Question 20051103
Inquiry Details
References:
#1: 2004 SEER Manual, C-432. App C, July 2003
#2: ICD-O-3
Question:
Discussion:
For melanoma, many path reports document the presence or absence of regression. At what point does the presence of regression become significant enough to code it for histology and for CS Extension?
Example 1: Skin biopsy showed malignant melanoma, Breslow thickness 0.38 mm, Clark's level II, ulceration is absent, regression is present.
Example 2: Punch biopsy showed malignant melanoma, Clark's level II, 0.34-mm maximum depth of invasion, with apparent regression.
Example 3: Skin biopsy showed lentigo maligna undergoing regression.
Answer:
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.
