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SEER Inquiry System - Report
Produced: 10/18/2025 8:21 AM
Question 20220049
Inquiry Details
References:
Solid Tumor Rules. Lung, September 2021 Update
Question:
Solid Tumor Rules/Multiple Primaries--Lung: How many cases should be abstracted for a patient with 2022 wedge biopsy of right upper lobe acinar predominant lung adenocarcinoma and wedge biopsy of right lower lobe lepidic predominant adenocarcinoma if there is concern for diffuse spread throughout the lungs secondary to the lymphangitic carcinomatosis and possible diffuse pneumonic type of adenocarcinoma? See Discussion.
Discussion:
Acinar predominant adenocarcinoma measures at least 12 mm and involves wedge biopsy margins, while the lepidic predominant adenocarcinoma measures 11 mm and does not involve the margins of that separate specimen. Pathologist also notes, “CT findings of diffuse coarse reticular nodular opacity, these findings may represent pneumonic type adenocarcinoma/diffuse pulmonary involvement or intrapulmonary metastasis. Both of these scenarios have the corresponding stages of pT4 (if thought to be ipsilateral) or M1a (if thought to also involve the contralateral lobe).”
Patient declined any further treatment and transitioned to hospice before expiring less than 1 month after wedge biopsies.
It is unclear if Rule M6 would apply to these two specimens with different subtypes since this scenario is not specifically addressed in the M rule definitions.
Answer:
Abstract two separate primaries when separate/non-contiguous tumors are two or more different subtypes/variants in Column 3 of Table 3 using Rule M6 in the Solid Tumor Rules (September 2021 Update). They represent two subtypes/variants of the same NOS histology. When coding histology, tissue from pathology takes precedence over imaging, including when stated as differential diagnoses based on the CT scan, as noted by the pathologist in this example.
