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SEER Inquiry System - Report
Produced: 01/06/2026 3:48 PM
Question 20130072
Inquiry Details
References:
2007 MP/H Rules
Question:
MP/H Rules/Multiple primaries--Lung: How many primaries are accessioned when the right lower lobe lung has two adenocarcinomas, both with lepidic pattern, if the tumor board staged these tumors as separate primaries? See Discussion.
Discussion:
Per pathology report
- Lung, right lower lobe, wedge excision (A): Invasive moderately differentiated adenocarcinoma with focal lepidic pattern (pT1a, pN0).
- Right lower lobe, completion lobectomy (F): Separate focus of well differentiated adenocarcinoma with lepidic pattern (<4mm) (see comment).
- COMMENT: The block F7 shows a microscopic focus of adenocarcinoma with lepidic growth pattern. This most likely represents a separate primary tumor since the stapled margins were all negative for involvement. This focus measures less than 0.4 cm.
- Tumor focality: Most likely two separate primary tumor nodules. Histologic type: adenocarcinoma, mixed type (NOS and lepidic type).
The tumor board has staged this as two separate primaries and is treating it as such. They are not considering the second focus metastatic even though it is the same histology. Lepidic is not in the ICD-O-3. Is lepidic a new term for histology?
Answer:
For cases diagnosed 2007 and later, accession a single primary, adenocarcinoma [8140/3] of the right lower lobe lung. The steps used to arrive at this decision are:
Step 1: Open the Multiple Primary and Histology Coding Rules Manual. Choose one of the three formats (i.e., flowchart, matrix or text). Go to the Lung MP rules because site specific rules have been developed for this primary.
Step 2: Start at the MULTIPLE TUMORS module, rule M3. The rules are intended to be reviewed in consecutive order within a module. Stop at rule M12. Accession a single primary when the patient has two tumors in the same lung with the same histology.
Keep in mind that physicians follow different "rules" to determine the number of primaries. Even though the physicians consider this case to represent two primaries, the MP/H rules instruct you to accession one primary.
We have received quite a few questions about the term lepidic. Below is the general definition of lepidic that will be added to the next MP/H revision.
"Lepidic" is a growth pattern meaning that tumor cells are growing along the alveolar septa. It is characteristic of bronchioloalveolar carcinoma (BAC), but not diagnostic of it. The diagnosis of BAC also requires no stromal, vascular, or pleural invasion. Lepidic growth may be seen in other adenocarcinomas, including metastases to lung from other sites. It is not a type/subtype of adenocarcinoma. For lepidic lung neoplasms, code the histology indicated, for example BAC.
