Step 2 CK · Internal Medicine · Pulmonology

Lung Cancer & Solitary Nodule

Name: Lung Cancer & Solitary Nodule
Creator: Veli Bakalov, MD

From an incidental nodule to cell type, staging, and cessation

Pulmonology·Pleural, Mediastinal & Thoracic Oncology·4 min read·9 high-yield points·Reviewed by Veli Bakalov, MD @HemeOncBuddy

Study materialsNo account needed

Card deckActive-recall cards · quick checks · quiz

High-yield

A solitary pulmonary nodule is ≤3 cm and surrounded by lung; age over 40, smoking, size over 8 mm, spiculation, upper-lobe location, subsolid density, and growth favor cancer, so compare with old films first.
Popcorn calcification = hamartoma; central, laminated, or diffuse calcification = old granuloma; eccentric or stippled calcification is not reassuring; a solid nodule stable over 2 years is benign.
Fleischner (incidental solid nodule, age ≥35): under 6 mm no routine follow-up, 6–8 mm CT at 6–12 months, over 8 mm CT at 3 months, PET-CT, or biopsy.
Screen with annual low-dose CT at age 50–80 with ≥20 pack-years who smoke now or quit within 15 years; stop after 15 smoke-free years or limited life expectancy.
Adenocarcinoma = peripheral, most common overall and in nonsmokers/women (EGFR, ALK, KRAS); squamous = central, cavitating, PTHrP hypercalcemia; small cell = central, SIADH, ectopic ACTH, Lambert-Eaton.
Lambert-Eaton (anti-voltage-gated calcium channel, small cell) weakness improves with repeated use, unlike myasthenia gravis.
Pancoast tumor: Horner syndrome (sympathetic chain), C8–T1 arm pain with hand wasting, and SVC syndrome.
Early NSCLC → lobectomy (segmentectomy for peripheral tumors ≤2 cm); metastatic NSCLC → targeted therapy (osimertinib for EGFR, ALK inhibitors) or anti-PD-1/PD-L1; SCLC → platinum-etoposide with chemoradiation then durvalumab (limited) or with immunotherapy (extensive), plus prophylactic cranial irradiation or MRI brain surveillance.
Smoking cessation is the highest-yield intervention: use the 5 A's, and varenicline (partial nicotinic agonist) is the most effective single drug, best combined with counseling.

The solitary pulmonary nodule

Definition. A solitary pulmonary nodule is a lesion ≤3 cm completely surrounded by lung. Anything larger than 3 cm is a mass, which is far more likely to be cancer. The first step with any nodule is to compare it with old imaging.

Reading a nodule

Feature	Favors malignancy	Favors benign
Patient	Age >40, smoker	Young nonsmoker
Size	>8 mm	Small
Margins and location	Spiculated or irregular; upper lobe	Smooth
Density	Part-solid or ground-glass	Solid and calcified in a benign pattern
Calcification	Eccentric or stippled (not reassuring)	Popcorn (hamartoma); central, laminated, or diffuse (old granuloma from TB or histoplasmosis)
Behavior over time	Growth	Solid nodule stable for >2 years

The 2-year rule applies to solid nodules. Ground-glass and part-solid nodules can grow slowly and are followed longer.

PET-CT. PET-CT helps characterize nodules >8 mm. It can miss very small lesions, ground-glass adenocarcinomas, and carcinoid tumors, and infection or granulomas can light up falsely.

Follow-up and screening

Fleischner 2017. These criteria apply to incidental solid nodules in adults aged ≥35. They do not apply to screening CTs, patients with known cancer, or immunosuppressed patients. Higher-risk patients get shorter intervals.

<6 mmNo routine follow-up in a low-risk patient.
6–8 mmCT at 6–12 months.
>8 mmCT at 3 months, PET-CT, or biopsy.

Screening (USPSTF 2021). Offer annual low-dose CT to adults aged 50–80 with a ≥20 pack-year history who currently smoke or quit within the past 15 years. Stop once the person has been smoke-free for 15 years, or when a health problem limits life expectancy or the ability to undergo curative treatment. Chest x-ray and sputum cytology are not screening tests.

50–80years of age

≥20pack-years

≤15 ysince quitting (or still smoking)

The 2021 update broadened the older NLST criteria (age 55–74, 30 pack-years) to age 50–80 and 20 pack-years, which brings more women and Black smokers into screening.

Cell types

Two treatment families. Non-small cell lung cancer (NSCLC, about 85%) includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. It is staged by TNM and is potentially resectable when localized. Small cell lung cancer (SCLC, about 15%) is a central, aggressive neuroendocrine tumor arising from Kulchitsky cells. It is usually metastatic at diagnosis, so it is staged as limited or extensive and treated with chemotherapy and radiation rather than surgery.

Lung cancer by cell type

Type	Location and link	Pathology	Paraneoplastic and associations
Adenocarcinoma	Peripheral; most common overall and in nonsmokers and women	Gland-forming; driver mutations EGFR, ALK, KRAS	Hypertrophic osteoarthropathy (clubbing); migratory thrombophlebitis (Trousseau)
Squamous cell	Central; smoking-linked; cavitates	Keratin pearls, intercellular bridges	PTHrP → hypercalcemia with suppressed PTH
Small cell	Central; strongly smoking-linked; early widespread metastasis	Neuroendocrine (Kulchitsky) cells	SIADH (hyponatremia); ectopic ACTH (Cushing); Lambert-Eaton (anti-voltage-gated calcium channel)
Large cell	Peripheral; smoking-linked	Undifferentiated, pleomorphic cells	Poor prognosis

Squamous is central, smoking-linked, and makes PTHrP ("Sentral"). A central mass with hypercalcemia and no bone metastases is squamous cell carcinoma until proven otherwise.

Paraneoplastic and local syndromes

Small cell syndromes. SIADH causes euvolemic hyponatremia with low serum osmolality and inappropriately concentrated urine. Ectopic ACTH causes Cushing syndrome, often with hypokalemia and little time for the classic body habitus to develop. Lambert-Eaton myasthenic syndrome comes from antibodies against presynaptic voltage-gated calcium channels.

Lambert-Eaton weakness is proximal and improves with repeated use, with hyporeflexia and autonomic symptoms. Myasthenia gravis weakness worsens with use.

Pancoast (superior sulcus) tumor. A tumor at the lung apex, usually squamous cell or adenocarcinoma, that invades nearby structures:

The sympathetic chain → Horner syndrome (ptosis, miosis, anhidrosis)
The C8–T1 brachial plexus → shoulder and arm pain with wasting of the hand muscles
Mediastinal vessels → SVC syndrome

SVC syndrome. Any apical or central tumor can compress the superior vena cava, causing facial and arm swelling, distended neck and chest-wall veins, and dyspnea.

Treatment and smoking cessation

Treatment by type and stage

Disease	Approach
Early-stage NSCLC	Surgical resection (lobectomy, or segmentectomy for peripheral node-negative tumors 2 cm or smaller), with or without adjuvant chemotherapy; check PFTs to confirm the patient can tolerate resection
Locally advanced NSCLC	Chemoradiation
Metastatic NSCLC	Test for driver mutations. Targeted therapy if present (EGFR TKI osimertinib; ALK inhibitors); otherwise immunotherapy (anti-PD-1/PD-L1), often with chemotherapy
SCLC	Limited stage: concurrent platinum-etoposide chemoradiation, then durvalumab consolidation. Extensive stage: platinum-etoposide plus immunotherapy. After a response, prophylactic cranial irradiation or MRI brain surveillance; surgery rarely

Smoking cessation. Cessation is the single highest-yield intervention. Use the 5 A's at every visit:

Ask about tobacco use
Advise quitting
Assess readiness to quit
Assist with the attempt
Arrange follow-up

Drugs for cessation. Combine counseling with drug therapy. Varenicline, a partial nicotinic agonist, is the most effective single drug. The alternatives are bupropion and nicotine replacement. Combining agents with counseling gives the best quit rates. Avoid bupropion in patients with seizure disorders or eating disorders, because it lowers the seizure threshold.