A patient with a 65 pack-year smoking history, type 2 diabetes, and prosthetic complications, presents with a CT scan showing a cavitary mass extending into the hilar region, what type of cancer is most likely?

Primary Lung Cancer: Squamous Cell Carcinoma

In a patient with a 65 pack-year smoking history presenting with a cavitary lung mass extending into the hilar region, squamous cell carcinoma is the most likely diagnosis. 1

Clinical Reasoning

Cavitation as a Key Diagnostic Feature

• Cavitation in lung masses strongly suggests squamous cell carcinoma, particularly in heavy smokers, as peripheral squamous cell carcinomas with cavitation are well-documented presentations. 1
• Large cell carcinoma can also present with central necrosis or cavitation in the lung periphery, but this is less common than squamous cell carcinoma in the context of hilar extension. 2
• Adenocarcinoma, now the most common lung cancer overall, typically presents as peripheral nodules or masses but rarely cavitates. 1

Hilar Extension Pattern

• Squamous cell carcinomas classically arise in central bronchi with local extension into the hilum and mediastinum, making this anatomic distribution highly characteristic. 1
• The combination of hilar involvement with cavitation creates a particularly strong signature for squamous cell histology in heavy smokers. 1
• Small cell carcinoma typically presents with bulky hilar or mediastinal adenopathy and distant metastasis rather than a discrete cavitary mass. 1

Smoking History Impact

• A 65 pack-year history represents extremely heavy tobacco exposure, which is the single most important causative factor for bronchogenic carcinoma, particularly squamous cell and small cell types. 2
• Heavy smoking history serves as both an etiologic risk factor and should prompt consideration of lung cancer screening protocols for this high-risk population. 1
• This patient would have qualified for annual low-dose CT screening per U.S. Preventive Services Task Force guidelines, which target patients with ≥20 pack-year smoking history. 1, 3

Diagnostic Algorithm

Immediate Next Steps

• Obtain CT chest with IV contrast to fully characterize the mass, assess mediastinal and hilar lymphadenopathy, and evaluate for metastatic disease. 1, 4
• IV contrast improves detection of mediastinal and hilar adenopathy by distinguishing nodes from mediastinal vessels and aids in delineating soft tissue extension. 1
• Contrast-enhanced CT is superior to non-contrast imaging when evaluating hilar masses and assessing for nodal staging. 4

Tissue Diagnosis Strategy

• Bronchoscopy with endobronchial biopsy should be the initial invasive procedure given the central location with hilar extension, which suggests likely endobronchial involvement. 5
• For central lesions with suspected airways involvement, bronchoscopy has high diagnostic yield and allows direct visualization of the airways. 5
• If bronchoscopy is non-diagnostic and the patient is not a surgical candidate, transthoracic needle aspiration (TTNA) can provide tissue diagnosis, though it carries higher pneumothorax risk for central lesions. 5

Staging Considerations

• Evaluate for mediastinal lymph node involvement using endobronchial ultrasound-guided needle aspiration (EBUS-NA) if accessible nodes are identified on CT. 4
• Screen for distant metastases to lymph nodes, liver, adrenal glands, bone, and brain, as these are the most common sites. 1
• Consider PET-CT for comprehensive staging, particularly if surgical resection is being considered. 4

Critical Pitfalls to Avoid

• Do not rely on chest radiography alone, as sensitivity for detecting pulmonary lesions is only 28% compared to CT, and up to 72% of lesions may be missed. 1, 4
• Do not assume the diagnosis without histological confirmation, as benign conditions like tuberculosis and fungal infections can present with cavitary masses in the hilar region. 4
• Do not overlook the possibility of a synchronous second primary lung cancer, as patients with heavy smoking history have a 7-14% risk of having a second lung primary at initial staging. 1, 3
• Avoid ordering CT without and with contrast (dual-phase) as there is no supporting literature for this approach in standard lung mass evaluation. 1, 3, 4

Comorbidity Considerations

• The patient's type 2 diabetes does not significantly alter the differential diagnosis but may impact surgical candidacy and wound healing if resection is planned. 6
• Assess cardiopulmonary reserve carefully given the extensive smoking history, as this will determine eligibility for surgical resection versus medical management. 5