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There are two histologies provided in the final diagnosis, malignant spindle cell neoplasm (8004/3) and atypical fibroxanthoma (8830/3). There is a definitive diagnosis of the non-specific histology, but the more specific histology is only described using ambiguous terminology.

The external ear (C442) is included in the Head and Neck schema for diagnosis year 2018 and later. The Head and Neck Histology Rules indicate ambiguous terminology cannot be used to code a more specific histology. So ignoring the atypical fibroxanthoma, because it is modified by ambiguous terminology, we are left with a non-reportable site and histology combination (C442, 8004/3).

Diagnoses of malignant atypical fibroxanthomas are regularly diagnosed using the syntax above in our area. Follow-up with the physician or pathologist is generally not possible as these cases are received from dermatopathology clinics only. The pathology report is the only information that will be received. If the reportable diagnosis of malignant atypical fibroxanthoma is ignored per the current Solid Tumor Rules, incidence cases will be lost.

Core biopsy of left breast at 2:00: Invasive ductal carcinoma, Nottingham score 6/9.

Core biopsy of left breast at 4:00: Invasive mucinous carcinoma (variant of ductal carcinoma), Nottingham score 5/9.

Post neo-adjuvant mastectomy: Main (largest tumor): Invasive ductal carcinoma, upper outer quadrant grade 2. Secondary tumor: mucinous carcinoma, grade 1 at 4:00.

Example: Right breast core biopsy found ductal carcinoma in situ in the upper outer quadrant. Subsequent resection has a final diagnosis of invasive mucinous carcinoma, grade 1, measuring approximately 7 mm, with close margins. See staging summary. Gross description mentions only the primary tumor with associated marker clip from previous biopsy.

Breast Cancer Staging Summary lists (testing and margins removed for brevity):

Procedure type: Lumpectomy.

Specimen laterality: Right.

Tumor size: 7mm.

Histologic type: Invasive mucinous carcinoma.

Histologic grade (Nottingham histologic score): Grade 1, (score 5/9).

Tumor focality: Single focus.

Lymph-vascular invasion: Not identified.

Treatment effect: No known therapy.

Ductal carcinoma in situ (DCIS): Present.

Architectural pattern: Cribriform.

Nuclear grade: Grade 1.

Necrosis: Not identified.

Calcifications: Not identified.

Estimated size/extent of DCIS: Spanning an area measuring 15mm.

Pathologic stage: pT1b, pNx. (AJCC 8th ed).

Distant metastasis: Not applicable.

Additional findings: Background lobular carcinoma in situ (LCIS), flat epithelial atypia (FEA), and atypical ductal hyperplasia (ADH).

According to the 2018 SEER Manual, Sentinel Lymph Nodes (SLNs) Examined and SLNs Positive are included in Regional Nodes (RNs) Examined and RNs Positive when both a sentinel node biopsy procedure and a subsequent dissection procedure are performed or a sentinel node biopsy procedure is performed during the same procedure as the regional node dissection.

Appendix E1 of the 2018 SEER manual references a similar diagnosis as being reportable for vulva and vagina only. However, the WHO Classification of Tumors of the Urinary System and Male Genital Organs (4th ed) does include high grade penile intraepithelial neoplasia as a synonym for 8077/2.

The Solid Tumor Rules instruct us not to use differentiation for coding histology unless it is specifically listed in the table. The terminology non-small cell carcinoma with neuroendocrine differentiation is not in lung histology Table 2.

However, SINQ 20150033, prior to Solid Tumor rules, indicates this diagnosis should be coded to 8574 (adenocarcinoma/carcinoma with neuroendocrine differentiation).

This presentation appears to represent distinctly different histologies. However, because the 2018 histology diagnosis is not in the table and the prior SINQ appears to disagree with current instruction, it is not clear how to apply the M rules to this case. The outcome of the histology coding will affect the number of primaries reported in this case.

Table 3 (Specific Histologies, NOS, and Subtypes/Variants) lists Ewing sarcoma as a synonym for Peripheral primitive neuroectodermal tumor 9364. Presumably, this is to be used for the reportable malignant peripheral nerve tumors when diagnosed as pPNET or Ewing sarcoma. However, this patient has a type of central (or CNS) primitive neuroectodermal tumor (histology 9473). Table 3 does not list central primitive neuroectodermal tumor (PNET or CPNET) as a valid histology for CNS tumors.

While Table 3 does not list all the possible histologies for the CNS, it currently is not clear how one would arrive at the histology code for a CNS Ewing sarcoma family tumor with CIC alteration, as this is recognized as a new entity for primitive neuroectodermal tumors of the CNS (i.e., PNET, histology 9473) per multiple journal articles. Ewing sarcoma family tumors include both peripheral PNET and central PNET tumors, but to code this histology as a peripheral PNET (9364) in this case seems incorrect when the primary tumor is stated to be of central nervous system origin, not peripheral nervous system origin.

For example, pathologic diagnosis is non-small cell carcinoma with squamous features. The medical oncologist describes this as squamous cell carcinoma and begins treatment regimen. As I interpret the rules, we would use code 8046, non-small cell carcinoma, because of instruction 2 and the fact that features is not included in the list of ambiguous terminology.

Example: Patient diagnosed following a resection of a cystic mass at L2-4 that proved an intradural tumor excision with final diagnosis of schwannoma, WHO grade 1.

Per new Solid Tumor Rules, the primary site in this case should be coded C476 (peripheral nerves of trunk, NOS) and histology is 9560/0 (schwannoma, NOS). However, there are currently no coding options in the Soft Tissue of Trunk and Extremities EOD schema relating to a benign tumor. Likewise there are no coding options in the Soft Tissue and Sarcoma Summary Stage 2018 schema relating to a benign tumor.

How should EOD 2018 and Summary Stage 2018 be coded for reportable benign schwannomas of the spinal nerve roots?