Two Lung Lesions, an Adrenal Nodule, and an Ambiguous Pathology Line
A 66-year-old man with a 45 pack-year smoking history presents with hemoptysis. CT chest shows a 3.4 cm right upper lobe mass, a 1.2 cm left lower lobe nodule, and a 1.6 cm left adrenal nodule. PET shows all three lesions are FDG-avid with no other disease.
Right upper lobe core biopsy: moderately differentiated squamous cell carcinoma, p40 positive, TTF-1 negative. Left lower lobe biopsy: poorly differentiated carcinoma, favor metastatic squamous cell carcinoma. Adrenal fine-needle aspiration: malignant cells, consistent with metastatic carcinoma. Molecular testing on the right upper lobe specimen shows PD-L1 tumor proportion score 55% with no EGFR, ALK, ROS1, or BRAF alterations.
The medical oncologist documents metastatic squamous cell carcinoma of the lung and plans carboplatin, paclitaxel, and pembrolizumab. The patient also has a history of prostate acinar adenocarcinoma in 2016, Gleason 4+3, treated with prostatectomy, with an undetectable PSA since.
1. How many primary tumors should be abstracted for this patient, and how do the ambiguous phrases favor metastatic and consistent with metastatic affect the decision?
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Two primaries: the 2016 prostate adenocarcinoma and one lung primary. The prostate cancer is a separate, earlier primary with different histology, and an undetectable PSA does not change that; it is not a metastasis and is not merged with the lung case.
For the lung, the key question is whether the left lower lobe and adrenal lesions are metastases of the right upper lobe squamous carcinoma or new primaries. The solid tumor rules make the physician's designation of metastatic disease decisive. Here the oncologist has documented metastatic squamous cell carcinoma and is treating systemically rather than with local therapy to the left lung, and the pathology uses favor metastatic squamous for the left lesion and consistent with metastatic carcinoma for the adrenal. Read together, these support a single lung primary with metastatic spread, not three separate primaries. The phrases favor and consistent with are not definitive on their own, but they are consistent with the clinician's stated diagnosis, and registry practice accepts a diagnosis when the physician documents and treats it as such.
If the record had been silent or contradictory, the correct action would be a physician query asking directly whether the left lower lobe lesion is metastatic or a synchronous primary. The answer changes the number of primaries, the stage, and the treatment fields, so it must be resolved and documented, not inferred.
2. Assign the histology and grade for each site and explain how you would code the ambiguous lesions if the clinician does not respond to a query.
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Right upper lobe: squamous cell carcinoma, code 8070/3, grade 2 because the report calls it moderately differentiated. This is the primary and the only site that receives a full histology code for the lung case.
Left lower lobe and adrenal: if they are metastatic, they receive no separate histology code of their own; they are part of the same primary and are captured in the stage and in text documentation. Coding them as carcinoma NOS would incorrectly imply a second, less-differentiated primary.
If the clinician does not respond to a query, do not invent a determination. The default is to code only what is documented with reasonable confidence: keep one lung primary with the right upper lobe histology, note in the abstract that the left lower lobe and adrenal were designated metastatic by the treating oncologist, and leave the query in the record as unanswered. If the evidence later shows the left lesion was treated as a separate primary, add a second lung abstract with the best-supported histology from that specimen, which would be poorly differentiated carcinoma, favor squamous, coded according to your manual's ambiguous terminology rules. The registrar's job is to reconcile the record, not to overrule the pathologist or the oncologist without documentation.
3. Assuming one lung primary with the described spread, assign T, N, M, and stage group under AJCC 8th edition, and show your reasoning.
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T is assigned from the largest tumor in the lung, the 3.4 cm right upper lobe mass, which falls in the 3 to 4 cm band and is therefore T2a. The left lower lobe lesion is in the contralateral lung and is not a T descriptor; it is metastatic disease.
N is N0, because no nodal involvement is described in the imaging, biopsy, or oncologist's note.
M requires care. A nodule in the contralateral lung is M1a, while a single extrathoracic metastasis is M1b. This patient has both: a contralateral lung nodule and a solitary adrenal metastasis. When more than one M category applies, assign the highest. The adrenal lesion is a single extrathoracic site, so M1b applies rather than M1c, which requires multiple extrathoracic metastases in one or more organs.
The stage group for any T, any N with M1a or M1b is stage IVA. So this is T2a N0 M1b, stage IVA. Note the trap: the adrenal lesion alone would already make this stage IV, but the presence of a contralateral lung nodule does not push it to IVB. If imaging later shows additional extrathoracic sites such as liver or bone, reassign M1c and stage IVB.