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Patient had a radical pharyngectomy showing a glossotonsillar sulcus tumor with high grade squamous cell carcinoma and adjacent high grade mucoepidermoid carcinoma. The pathologist commented, the tumor is composed of high grade mucoepidermoid carcinoma and high grade conventional-type squamous cell carcinoma that are immediately adjacent to one another. Given that the tumors are arising so close together and could represent a single neoplastic process with divergent morphologies, they are staged together.

Employing Solid Tumor Manual Rule M1 (single primary if unable to determine if there is a single or multiple tumors), it was determined that this should be reported as a single tumor because the pathologist referred to the case as both a tumor singular and tumors pleural. However, the Solid Tumor Manual Histology Rules for a Single Tumor do not appear to have an instruction for coding this histology combination.

Example: Patient is found to have a 9.4 cm GIST in the jejunum and 2 cm GIST in the stomach during resection, neither stated to be outright malignant. Similar to the instruction in SINQ 20190041, this case is coded as a malignant jejunal primary due to multifocal tumor. However, it is unclear how to account for the stomach tumor, or any other multifocal tumor for GIST, when coding EOD and Summary Stage.

Is an M rule needed to address multiple tumors and Note 2 in Table 3? Does Note 2 in Table 3 apply when multiple tumors exist and one tumor contains only ductal carcinoma?

The M Rules currently confirm that a metaplastic carcinoma (whether it is involved with ductal or lobular) and a separate ductal carcinoma are separate primaries because these histologies are on different rows in Table 3 (separate primaries per M14). There is no specific rule regarding metaplastic carcinomas in the Multiple Tumors (M Rules) module, so presumably, the presence of a separate ductal carcinoma is not lumped into Note 2 in Table 3 for metaplastic carcinoma.

However, the note is confusing when there are multiple tumors involved because it appears to the registrars there are two options for coding the histology. To some registrars, the rules indicate it does not matter if the tumor is predominantly ductal carcinoma as long as some percentage of metaplastic carcinoma is present, code histology to metaplastic carcinoma. For other registrars, the presence of solely a ductal carcinoma in a second tumor is a separate primary from the separate metaplastic carcinoma.

The M rules and Note 2 need to clarify this issue to promote consistency.

This question was prompted from preparing SEER*Educate coding exercises. We will use the answer as a reference in the rationales.

Bone marrow, right iliac crest (aspirate smear, touch preparation, clot section and core biopsy): Hypercellular marrow (40-50%) with plasma cell neoplasm (see Comment): " No evidence of metastatic carcinoma. " Adequate iron storage.

Comment: CBC data shows normocytic anemia. Flow cytometric analysis of bone marrow detects a kappa restricted plasma cell population that expresses CD138 and CD38. CD56 is positive. CD19 and CD20 are negative. T lymphocytes are immunophenotypically unremarkable. Polyclonal B lymphocytes are detected. Blast gate is not significantly increased. Immunohistochemical stains are performed on the biopsy core and clot section for greater sensitivity and further architectural assessment with adequate controls. CD138 positive plasma cells comprise > 70% of the total cellularity. AE1/AE3 is negative. Taken together, the morphologic and immunophenotypic findings are consistent with a diagnosis of plasma cell neoplasm. Trilineage hematopoietic activity as are seen.

The Hematopoietic and Lymphoid Neoplasms Database (Heme DB) definition for systemic mastocytosis with an associated hematological neoplasm (SM-AHN, 9741/3) states SM-AHN is a variant of systemic mastocytosis that arises with a myeloid disease of non-mast cell lineage (e.g., MDS, MPN, etc.) and that,

However, SINQ 20130172 conflicts with the Heme DB stating the systemic mastocytosis and the associated hematological neoplasm are a single primary coded to a single histology (9741/3) per Rule M2.

Example: MRI found an intradural, extra-axial mass at T12/L1 with possible intramedullary component. Resection of the intradural intramedullary and extramedullary spinal cord tumor found a capillary hemangioma pathologically. The microscopic description on the path report describes a tumor with extensive vascularity involving the dura.

Should we equate the statement of capillary to mean the tumor is arising in a blood vessel as we do for venous hemangioma (non-reportable per SINQ 20130001)? Or should it be reportable as C700, 9131/0 because it is described as involving the dura (intradural, intramedullary and extramedullary)?

Example: Posterior fossa tumor resection final diagnosis was medulloblastoma, WHO Grade IV. The diagnosis comment notes the current tumor resection reveals large irregular reticulin-free nodules with streams of neoplastic cells in a fibrillary background in association with narrow reticulin-rich internodular strands of poorly differentiated neoplastic cells. Taken together, these findings are indicative of medulloblastoma with extensive nodularity. The diagnosis comment provided only one histology.

Per the 2018 Solid Tumor Manual, Malignant CNS, Priority Order for Using Documentation to Identify Histology instructions, an addendum or comment has priority over the final diagnosis. Although indicative is not listed on any ambiguous terminology list, is this an ambiguous diagnosis that must be ignored? Or does the diagnosis comment in this case provide a single, specific diagnosis of medulloblastoma with extensive nodularity?

Per the site validation list: https://seer.cancer.gov/icd-o-3/sitetype.icdo3.20190618.pdf#search=site%20validation, ill-defined sites (ILL-DEFINED C760-C768) does not include 8070- Squamous cell carcinoma as a valid histology. Therefore when a Cervical Lymph Node and Unknown Primary Tumor of the Head and Neck is submitted with a C760 and 8070/3, it requires an override be set.