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Abstract a single primary using Solid Tumor Rules, Malignant CNS and Peripheral Nerves, Rule M10 based on the information provided.  Rule M10 applies as both non-contiguous tumors are of the same histology; i.e., on the same row in Table 3. As MPNST can arise in many sites, look for information about the precise location and tissue type in which the tumor arose. For example, if the tumors are stated to arise in soft tissue, follow the Multiple Primary Rules for Other Sites.

Both WHO Classification of Central Nervous System Tumors and WHO Classification of Soft Tissue and Bone Tumors state that MPNST is a malignant spindle cell tumor often arising from a peripheral nerve, from a pre-existing benign nerve sheath tumor, or in a patient with neurofibromatosis type 1 (NF1).

Future updates will move C470-C479 from CNS to other sites module.

Assign code 8742/2 (lentigo maligna) for “early lentiginous melanoma in situ.” ICD-O-3.2 lists the preferred term for 8742/2 as lentigo maligna (C44._).

Updated Answer July 2024

Code histology as myelodysplastic neoplasm with increased blasts (9983/3) based on the WHO Classification of Hematolymphoid Tumors, 5th edition, Beta version 2.  WHO lists MDS with increased blasts-2 (MDS-IB2) as a subtype of 9983/3.

Terms coded to 9983/3 include

• Myelodysplastic neoplasm with increased blasts
• Myelodysplastic neoplasm with increased blasts-1
• Myelodysplastic neoplasm with increased blasts-2
• Myelodysplastic neoplasm with increased blasts and fibrosis
• Subtypes: MDS with increased blasts-1 (MDS-IB1); MDS with increased blasts-2 (MDS-IB2); MDS with increased blasts and fibrosis (MDS-F)

When differences exist between WHO and ICC, assign the histology based on the WHO Classification.

Do not report serous borderline tumor–micropapillary variant of the ovary (8460/2, C569) as borderline ovarian tumors are not reportable. This applies to cases 2018 and later.

Do report serous borderline tumor–micropapillary variant of the testis as stated in SINQ 20220032. It is reportable for cases diagnosed Jan 1, 2021 and later.

For the example provided: For 2023 cases and forward, if no part of the surgery was performed, code Surgery of Primary Site 2023 (NAACCR Item #1291) as code A000 or B000 (no surgical procedure of the primary site).  Code Reason for No Surgery of Primary Site (NAACCR Item #1340) as code 2 (surgery of the primary site was not recommended/performed because it was contraindicated due to patient risk factors (comorbid conditions, advanced age, progression of tumor prior to planned surgery, etc.).

In contrast, if any part of the surgery was performed, assign the Surgery of Primary Site 2023 (NAACCR Item #1291) code that best reflects the extent of the surgery performed.  Code Reason for No Surgery of Primary Site (NAACCR Item #1340) as code 0 (surgery of the primary site was performed).

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For cases prior to 2023, apply the same approach using Surgery of Primary Site (NAACCR Item #1290) instead of Surgery of Primary Site 2023 (NAACCR Item #1291).

Assign 9380/1 for low grade glioma diagnosed 1/1/2018 forward and for low grade glioma diagnosed prior to 1/1/2018 assign code 8000/1 on the advice of our expert neuropathologists. The site/type combination of C71 _ and 9380/1 will flag histology/site/behavior edits which should be overridden.

Low grade glioma is an umbrella term or non-specific diagnosis, primarily seen on radiologic reports such as CT scans and MRIs. Often, the patient is actively followed with scans and surgical intervention delayed or not recommended. WHO Classification of Central Nervous System Tumors, 5th edition, does not recognize this term and indicates that tissue diagnosis (including genetic testing) is needed to provide a specific diagnosis. Since biopsy of these “neoplasms” is not routinely done, a definitive diagnosis is not available. Literature searches yielded conflicting information with some stating low grade gliomas are malignant with an indolent clinical course while others felt they were benign. Until such time as WHO proposes a code for this neoplasm, our expert neuropathologists recommend coding glioma, NOS with borderline behavior 9380/1. 

According to the 5th edition WHO Blue Book for Hematopoietic Neoplasms, Beta Version, (not released yet), nodular lymphocyte predominant B-cell lymphoma is an alternate name for 9659/3. We will update the Heme database once the 5th edition is released in print.

Assign histology code 8254/3 (mixed invasive mucinous and non-mucinous adenocarcinoma) to this lung tumor using Lung Solid Tumor Rules, Rule H4. This is a new code/term approved by IARC/WHO for ICD-O. Rule H4 instructs one to code the histology when only one histology is present. In this case, the pathologist indicates the tumor is mixed mucinous and non-mucinous histologies. The non-mucinous carcinoma that is seen in this mixed histology may be identified as: Adenocarcinoma in situ, minimally invasive adenocarcinoma, or lepidic predominant adenocarcinoma. In this case it is lepidic predominant adenocarcinoma. Lepidic is a recognized histology in lung. It is not unusual for the pathologist to indicate mixed non-muncinous and mucinous adenocarcinoma AND also list the non-mucinous subytpe. It is important to capture both mucinous and non-mucinous histologies which drives treatment, etc. 

Code Primary Site as Overlapping lesion of cervix uteri (C538). The 2023 SEER Program Coding and Staging Manual Primary Site Coding Instructions for Solid Tumors #4 says to code the last digit of the primary site code to ‘8’ when a single tumor overlaps an adjacent subsite(s) of an organ and the point of origin cannot be determined. This is also supported by the ICD-O-3, 3rd edition, note in the Topography section that states: In categories C00 to C809, neoplasms should be assigned to the subcategory that includes the point of origin of the tumor. A tumor that overlaps the boundaries of two or more subcategories and whose point of origin cannot be determined should be classified to subcategory ‘8.”

Assign Laterality code 4 (Bilateral involvement at time of diagnosis, lateral origin unknown for a single primary) in the situations you describe. Skin of upper limb and shoulder and Skin of other and unspecific parts of the face are listed as paired organs in the table Sites for Which Laterality Must Be Recorded In the 2023 SEER Manual.