Cavitating Mass in the Lungs

• What is it:
  • A cavitating mass in the lungs is a localized area of abnormal tissue growth with central necrosis or liquefaction, leading to the formation of an air- or fluid-filled cavity.
  • Cavitation is typically seen within a lung mass due to infection, malignancy, or other pathological processes.
• Etymology:
  • The term “cavitation” derives from the Latin word cavus, meaning “hollow,” describing the cavity formation within the mass.
• AKA:
  • Cavitary lesion, cavitating tumor (if malignancy is suspected).
• How does it appear on each relevant imaging modality:
  • Chest CT (preferred):
    • Parts: A thick-walled mass with a central cavity containing air, fluid, or both.
    • Size: Variable, depending on the underlying etiology.
    • Shape: Irregular or round margins with a cavity inside.
    • Position: May be central, peripheral, or in association with pre-existing lung pathology.
    • Character:
      • Wall thickness: Malignancies usually have thicker walls (>15 mm), while benign lesions often have thinner walls (<5 mm).
      • Presence of air-fluid levels: Indicates communication with the bronchial tree or superimposed infection.
      • Adjacent findings: Possible surrounding ground-glass opacities, consolidation, or lymphadenopathy.
  • Chest X-ray:
    • Appears as a thick-walled mass with a radiolucent center.
    • May show air-fluid levels.
    • Limited sensitivity for subtle features compared to CT.
  • PET-CT:
    • Increased metabolic activity (high SUV) is suggestive of malignancy.
    • Benign processes like infections may also show moderate uptake.
  • Ultrasound:
    • Rarely used but may show a hypoechoic lesion with internal air or fluid (pleural-based masses).
• Differential diagnosis:
  • Infectious:
    • Pulmonary abscess.
    • Tuberculosis with cavitation.
    • Fungal infections (e.g., aspergillosis, histoplasmosis).
  • Neoplastic:
    • Primary lung cancer with necrosis (e.g., squamous cell carcinoma).
    • Metastatic disease with cavitation (e.g., squamous carcinoma, sarcomas).
  • Inflammatory: Rheumatoid nodule, Wegener’s granulomatosis (GPA).
  • Trauma: Post-traumatic hematoma with secondary infection.
  • Congenital: Bronchogenic cyst with secondary infection.
• Recommendations:
  • Further evaluation:
    • Contrast-enhanced CT to better characterize the lesion and identify vascularity or bronchial communication.
    • PET-CT for metabolic assessment if malignancy is suspected.
    • Bronchoscopy for direct visualization and biopsy.
    • CT-guided biopsy for histopathological and microbiological analysis.
  • Follow-up imaging:
    • Short-interval CT for indeterminate lesions.
  • Clinical correlation:
    • Consider recent infections, malignancy risk factors (e.g., smoking), or autoimmune diseases.
• Key considerations and pearls:
  • Wall thickness is a key feature to distinguish between benign and malignant causes.
  • Air-fluid levels often suggest infection but can also be seen in necrotic tumors.
  • Adjacent findings, such as lymphadenopathy or invasion of surrounding structures, favor malignancy.
  • Cavitation in squamous cell carcinoma is a classic finding, especially in smokers.
  • Superimposed infection can complicate interpretation and management, especially in immunocompromised patients.

This structured format provides clarity and guidance for interpreting cavitating masses in the lungs.