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Report Produced: 03/09/2026 08:16 AM

Report Question ID Question Discussion Answer
20051103 CS Extension/Histology (Pre-2007)--Melanoma: When do the terms "regression is present," "apparent regression," or "undergoing regression" affect the coding of melanoma cases? See 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.

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.
20061051

Reportability--Melanoma: Is the final diagnosis for an excisional skin biopsy of "compound nevus with severe cytoarchitectural atypia and regression" reportable if a re-excision may be clinically indicated because there is an "overlap of morphology between malignant melanoma and nevi with severe atypia, and there's evidence of regression"?

Compound nevus with severe atypia is not reportable unless also stated to be malignant melanoma or melanoma in situ.
20061086

Reportability--Melanoma: Is an excisional biopsy of the skin with a diagnosis on the pathology report of "Tumoral melanosis" reportable by itself or must there be a pathologist note, such as "Note: Unless proven otherwise, tumoral melanosis should be considered as a regressed melanoma", in order for it to be reportable? See Discussion.

Skin, left upper back, exc Bx: Tumoral melanosis. Note: Unless proven otherwise, tumoral melanosis should be considered as a regressed melanoma.

If reportable, do we report a diagnosis of tumoral melanosis without a similar note?

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.
20061087

Reportability--Melanoma: Is the following reportable? See Discussion.

PATH: Skin, Lt back exc bx: compound nevus with severe cytoarchitectural atypia and regression. Comment: due to overlap of morphology between MM and nevi with severe atypia, and since there's evidence of regression, consideration for re-excision may be considered if clinically indicated. The final diagnosis, compound nevus with severe atypia, is not reportable. This diagnosis is not listed in ICD-O-3.
20081044 MP/H Rules/Behavior--Melanoma of Skin: How are histology and behavior coded for a "malignant melanoma in situ with regression"? See Discussion. Per the microscopic portion of the path report, there is a zone of regression within the confines of the lesion, such that the possibility of antecedent invasive disease at the site cannot be ruled out with certainty.

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.
20081045 MP/H Rules--Melanoma: How is histology coded for a regressing melanoma? See Discussion.

How is histology to be coded for the following tumors?

Example 1: Path showed malignant melanoma Histologic type: superficial spreading. Regression: present.

Example 2: Shave, mid back: malignant melanoma, lentigo melanoma type, level II, regression: present and prominent.

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].
20081055 MP/H Rules--Melanoma: How many primaries are represented if subsequent to a diagnosis of malignant melanoma of skin of left thorax in April 2006, a metastatic melanoma is discovered in the soft tissue of the abdomen and in the skin and subcutaneous tissue of the groin in late 2007? See Discussion.

4/20/06: skin left lateral thorax, excision: Pedunculated malignant melanoma, 0.5 CM in height, Clark's level 3, Breslow depth 0.5 CM, superficial ulceration noted. No host response. Margins clear.

6/19/06: Four sentinel LNs negative. Interferon therapy.

10/30/07: FNA of soft tissue, left lower abdomen: consistent with metastatic melanoma.

12/20/07 A) sentinel lymph node, left groin, biopsy: No morphologic or immunophenotypic findings support for metastatic melanoma (see comment). B) skin and subcutaneous tissue, left groin, excisional biopsy: Metastatic malignant melanoma (see comment). Lymphovascular invasion identified. Margins free of melanoma. Melanoma 1.5 MM from the closest designated deep margin and 5 MM from the designated 6:00 margin. C) skin, left groin/additional inferior margin, excisional biopsy: No significant histopathologic abnormality. No evidence of villus or melanoma or malignancy. Comment: A 0.8 cm metastatic nodular melanoma is present in the adipose tissue. The underlying skin is unremarkable. There is no evidence of ulceration, melanocytic lesion, melanoma in situ, or regression of melanoma. Block A1 is sent for immunohistochemical studies. The immunophenotypic findings provide no support for metastatic melanoma in lymph node. Please see the immunohistochemical study. The primary MD states "Recurrent intransit mets, left groin."

 For cases diagnosed 2007 or later, this is a single primary, melanoma of the thorax 4/20/06. The subsequent reports mention metastases, but do not document another primary. Do not count metastatic lesions as new primaries.
20100007 MP/H Rules/Histology--Melanoma: Regarding SINQ #20081044, when would you apply Rule H6 rather than Rule H5 for a cutaneous malignant melanoma given that you normally always have a specific cell type mentioned? For cases diagnosed 2007 or later, Rule H6 is used when you do not have a specific cell type other than regressing melanoma, or malignant melanoma, regressing. If you have regressing melanoma with a specific cell type, apply rule H5.
20210009

Solid Tumor Rules (2018, 2021)/Histology--Melanoma: In what situation will Rule H4 be used to code the histology to regressing melanoma? See Discussion.

Rule H4 states: Code 8723/3 (malignant melanoma, regressing) when the diagnosis is regressing melanoma. However, if the diagnosis was strictly regressing melanoma or malignant melanoma, regressing, the first rule that applies is Rule H1 because regressing melanoma is a single, specific histologic type and Rule H1 states: Code the histology when only one histologic type is identified. Following the current rules, one would never arrive at Rule H4. Should the H Rules be reordered? Or should an example of when one would use Rule H4 be added to clarify when to use this rule?

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.