What is the clinical significance of a 9 mm pleural-based nodule at the lateral right lung apex?

Clinical Significance of a 9 mm Pleural-Based Nodule at the Lateral Right Lung Apex

A 9 mm pleural-based nodule at the lateral right lung apex most likely represents benign apical scarring or an intrapulmonary lymph node and does not require routine follow-up imaging if it demonstrates typical benign morphologic features. 1, 2

Morphologic Assessment is Critical

The first step is to carefully evaluate the nodule's morphology on multiplanar reconstructions:

• Review coronal and sagittal CT images to assess the true shape and pleural relationship of this nodule, as transverse images alone can be misleading for apical pleural-based opacities 1, 2

• Benign features that would allow discharge without follow-up include: 1, 2

  • Pleural-based configuration with elongated shape
  • Straight or concave margins
  • Triangular, lentiform, or oval morphology
  • Homogeneous solid appearance
  • Fine linear septal extension to pleura

• Apical scarring is extremely common and frequently appears nodular on CT, particularly in the lung apices where pleural and subpleural scarring occurs routinely 1, 2

When No Follow-Up is Needed

British Thoracic Society guidelines explicitly state not to offer follow-up for typical perifissural or subpleural nodules that are homogeneous, smooth, solid with lentiform or triangular shape, either within 1 cm of a fissure or pleural surface and <10 mm. 1 Your 9 mm pleural-based nodule falls into this category if morphology is typical.

• The NELSON trial demonstrated that 20% of all nodules were perifissural/pleural-based, 16% showed growth, yet none were malignant after 5 years of follow-up 1, 3

• Fleischner Society 2017 guidelines confirm that follow-up CT is not recommended for nodules with perifissural or juxtapleural location and morphology consistent with intrapulmonary lymph nodes, even if average dimension exceeds 6 mm 1, 2

High-Risk Features That Would Change Management

You must actively look for concerning features that would mandate surveillance:

• Spiculated borders (OR 2.1-5.7 for malignancy) 1
• Displacement of adjacent pleura or fissure 1, 2
• Irregular or lobulated margins rather than smooth 1
• History of extrapulmonary malignancy 1
• Upper lobe location (though this nodule is apical, which is a common site for benign scarring) 1

If any of these high-risk features are present, perform follow-up CT at 6-12 months rather than discharging the patient. 1, 2

Risk Stratification if Morphology is Indeterminate

If the nodule lacks clearly benign morphologic features but also lacks high-risk features:

• Use the Brock prediction model for nodules ≥8 mm to calculate malignancy probability, incorporating age, smoking history, nodule diameter, spiculation, and upper lobe location 1

• For malignancy risk <10%: Perform CT surveillance with volumetric analysis at 3 months and 1 year 1

• For malignancy risk 10-70%: Consider PET-CT with Herder model risk reassessment (though PET has limited utility for nodules at the lower size threshold) 1

Common Pitfalls to Avoid

• Do not apply aggressive surveillance protocols to clearly benign-appearing pleural-based apical opacities – this leads to unnecessary radiation exposure, cost, and patient anxiety without improving outcomes 2

• Do not evaluate this nodule on transverse images alone – multiplanar reconstruction is essential to distinguish true nodules from pleural-based scars 1, 2

• Do not assume all pleural-based nodules are benign – larger perifissural nodules (>10 mm) in patients with known extrapulmonary cancer may rarely be malignant and warrant consideration of follow-up 1

• Do not ignore the clinical context – presence of previous malignancy, smoking history, and age significantly impact the pretest probability and should guide decision-making 1

Practical Algorithm

1. Obtain multiplanar CT reconstructions (coronal/sagittal views) 1, 2
2. If typical benign morphology (smooth, triangular/lentiform, pleural-based): No follow-up needed 1
3. If atypical morphology or high-risk features present: Follow-up CT at 6-12 months 1, 2
4. If indeterminate morphology: Calculate Brock score and manage according to risk stratification 1