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Report this case of leukemia cutis and code to bone marrow (C421) and leukemia NOS (9800/3) based on the information provided. Update the abstract if new information becomes available.

Leukemia cutis is the rare infiltration of neoplastic leukocytes into the epidermis, dermis, or subcutis from an existing leukemia that results in clinically identifiable cutaneous lesions. Leukemia cutis may precede, follow, or occur concurrently with the diagnosis of systemic leukemia. It is an advanced phase of the leukemia having a poor prognosis that also strongly correlates with additional sites of extramedullary involvement. This can alter the appropriate treatment regimen for a patient. It is a type of "metastasis" or spread of the leukemia cells. The "conventional" definition for leukemia cutis is the infiltration of skin from a bone marrow primary. It is most often diagnosed via skin biopsy—punch, shave, etc., utilizing IHC/biomarker testing and is commonly associated with CMML and acute myeloid leukemia (AML). As such, it a reportable condition especially when preceding a confirmed systemic leukemia diagnosis. In this situation, the diagnosis date would be the date of the positive leukemia cutis skin bx—punch, shave, etc. The case should be coded to C421; 9800/3 Leukemia NOS until the official systemic leukemia diagnosis is rendered. If possible, follow back should be conducted to determine the specific systemic leukemia histology (CMML; AML) and the treatment received. If the leukemia cutis follows or occurs concurrently with the diagnosis of a systemic leukemia, it is NOT a separate primary but merely an advanced stage of the systemic leukemia diagnosis.

Do not report angiomyxoma. ICD-O-3.2 assigns 8841/0 to this benign tumor. This includes superficial and deep (aggressive) angiomyxoma.

Code the specific histology as stated by the pathologist according to the site-specific instructions in the Solid Tumor Rules. When the histology provides a subtype/variant in addition to the HPV histology codes, code the subtype/variant as it is important to capture this histology as in the example provided. the instruction to code the subtype/variant over 8085 or 8086 applies to the following sites: oropharynx, cervix, vagina, vulva, anus, and penis. A note will be added indicatng this in 2025. 

Per 2024 Cancer PathCHART expert pathologist review, morphology codes 8085/3 and/or 8086/3 are valid and applicable to head and neck, oropharynx, cervix, vagina, vulva, fallopian tube, anus, and penis (reference: Cancer PathCHART: Product Downloads and Timelines). Other coding resources will be updated to reflect these changes in 2025.

Code Primary Site to C480 (retroperitoneum). 

Endometrial tissue may "break away” from the uterus and implant throughout the pelvic and abdominal cavities. This can occur in patients who suffer from endometriosis. This tissue remains behind when surgical removal of the uterus is done. Common sites of implantation are colon, peritoneum, retroperitoneum, and bladder. These cells may become malignant. When the uterus is no longer present (patient had surgical removal), code the site where the carcinoma was identified.

The site-morphology combination of C480 and 8380/3 was designated as an unlikely site-morphology combination by the Cancer PathCHART expert pathologist review, as this is a rare type of tumor. Assign a value of 1 in the Over-ride Site/Type [2030] data item in order to pass the Primary Site, Morphology-Type, Beh ICDO3, 2024 (SEER) edit.

The CPC ICD-O-3 Site Morphology Validation Lists (SMVLs) designate all tumor site-morphology combinations that are either valid or impossible as determined for the sites reviewed by the Cancer PathCHART initiative. These lists provide information on the Validity Status of specific tumor site and morphology combinations, similar to the way the ICD-O-3 SEER Site/Histology Validation List used to. However, the CPC SMVLs do not include information on the reportability of specific tumor site and morphology combinations. For tumor reportability, you will continue to use the Excel ICD-O-3.2 spreadsheets posted to the NAACCR ICD-O-3 Coding Updates website: https://www.naaccr.org/icdo3/, and the most recent SEER Manual and federal, state, local, and other standard setters' reportability requirements.

Sites may be added to certain combinations when indicated by ClinCORE review for Cancer PathCHART. Please note some sites were added in the 2024 update as a result of PathCHART review. A newly-formed Solid Tumor Editorial Board and its subgroups are currently working to evaluate the Solid Tumor Manual and make recommendations on ways to improve the structure and formatting of the manual and its content.

Follow the rules and instructions in the Other Sites STRs when assigning combination histology codes.

Histology Coding Rules

Use the Histology Coding Rules when assigning combination codes.

Coding Histology Information

Use this section that includes the mixed histology (Table 2) and site-specific histology tables (Tables 3-23) for one or more histologies within a single tumor. Do not use this section in place of the Histology Coding Rules.

While site-specific histology tables, based on current WHO Classification of Tumors books, have been added to Other Sites STRs, not all site groups have individual histology tables; coding may require the use of ICD-O and updates. The histology tables in Other Sites STRs include additional coding instructions and notes to assign the correct ICD-O code when appropriate.

The tables are not meant to be all-inclusive; rather they are intended to address difficult coding situations to facilitate the assignment of the correct histology code.

Table 2: Mixed and Combination Codes Instructions

Once you have identified the histology terms and have been instructed to use Table 2 by the Histology Coding Rules, compare the terms in the diagnosis to the terms in Column 1. When the terms match, use the combination code listed in Column 2. Use adenocarcinoma mixed subtypes 8255 as a “last resort” code.

Assign histology as DLBCL (9680/3) as supported by the WHO Classification of Hematolymphoid Tumors, 5th edition. It is consistent with how it would have been coded in the 4th edition. The Heme Manual and Database currently are based on the 4th edition. Physicians are using the 5th edition blue book, whereas the cancer registry field is not yet at this time.

Regarding the Heme Manual and Database, this type of scenario is not covered because it is part of the 5th edition WHO Blue Book. The database cannot be updated until the 5th edition is approved for implementation (2026).

Lymphoepithelial carcinoma is a subtype of SCC usually seen in skin or H&N sites and often associated with EBV. CPC SME review determined 8082/3 invalid for breast but did not recommend a substitute code. There were only 45 cases coded 8082 2001 to 2019. For this case, it's possible the lesion originated in the breast skin and progressed to breast tissue. SCC is a subtype of metaplastic breast carcinoma so one could argue it code be coded either 8575 or 8070. For this case, we recommend assigning 8500/3. Use text fields to record the details.

High grade dysplasia of the esophagus is reportable. The example will be corrected in the next edition of the SEER manual.

Report malignant spindle cell neoplasms consistent with atypical fibroxanthoma as directed by Appendix E.1 of the 2023 and 2024 versions of the SEER Manual using 8830/3 (fibroxanthoma, malignant).

We will update the answer in SINQ 20190102.  While the Other Sites Solid Tumor Rules address coding an NOS and specific histology sub-type/variant, this situation is not specifically addressed. We will also review the rules.