Benign Tumors of the Lung

I

Overview

• 1.

  These tumors account for less than 1% of all resected lung tumors.

• 2.

  They may be derived from epithelial, mesodermal, or endodermal cell lines.

• 3.

  Hamartomas account for greater than 75% of benign tumors of the lung.

• 4.

  Endobronchial tumors present with signs and symptoms related to airway obstruction (most often pneumonia) and bleeding.

• 5.

  Peripheral airway and parenchymal tumors usually present as incidental solitary pulmonary nodules.

II

History

• 1.

  The probability of malignancy rises with age; greater than 50 years of age raises risk of malignancy significantly.

• 2.

  Only 5% of all radiographically detected lung nodules prove to be malignant.

• 3.

  Smoking, family history, female sex, emphysema, chemical exposure, asbestos, or coal mining are risk factors for malignancy.

III

Physical Examination

• 1.

  Lymph node assessment—cervical, supraclavicular, and axillary

• 2.

  Dyspnea/shortness of breath (SOB)

• 3.

  Chest pain

• 4.

  Cough

• 5.

  Weight loss

• 6.

  Hemoptysis

• 7.

  Most commonly, nodules are asymptomatic and found incidentally.

IV

Initial Evaluation

• 1.

  Characterize the mass through imaging, that is, dedicated chest computed tomography (CT) scan, which is respiratory gated.

• 2.

  Based on features (nodule vs. mass), determine to monitor or establish a histologic diagnosis.

  • a.

    Nodule; ≤3 cm, regular borders and surrounded by normal parenchyma

  • b.

    Mass; greater than 3 cm, irregular (particularly speculated), extensions to pleura or adjacent structures or other associated abnormalities

V

Imaging

• 1.

  Comparison radiographs are essential.

• 2.

  Tumor doubling time

  • a.

    Malignant tumors double in weeks to months.

  • b.

    Benign tumors double over years or remain unchanged (solid nodules are followed for 2 years if unchanged as doubling time is inconsistent with malignancy).

• 3.

  Computed tomography

  • a.

    CT scanning is the standard modality to assess lung lesions and provides the following features:

    • (1)

      Location—upper lobe lesions are more often malignant.

    • (2)

      Size less than 1 cm have a 2%–6% risk of malignancy

    • (3)

      Attenuation—solid, mixed attenuation (partially solid) or ground-glass opacity (no solid component)

    • (4)

      Rate of growth

    • (5)

      Border—smooth (often benign) versus irregular (spiculation is statistically correlated with malignancy)

    • (6)

      Calcification—popcorn, laminated, central, and diffuse—all point to benign etiology

    • (7)

      Invasiveness into adjacent structures

    • (8)

      Hilar or mediastinal adenopathy (a smooth-edged lesion is considered a mass if associated with lymphadenopathy)

    • (9)

      Presence suspicious lesions that could herald metastatic spread

• 4.

  Positron emission tomography (PET) scan

  • a.

    Determines metabolic rate of tissues based on the uptake of fluorodeoxyglucose (FDG)

  • b.

    The intensity of uptake is measured in standardized uptake value (SUV), with a threshold of 2.5 or greater correlating with malignancy.

  • c.

    Inflammation (sarcoidosis) and infection (fungal granuloma) can be PET positive, typically less than 2.5 SUV.

  • d.

    When performed for patients with benign-appearing lesions, the PET scan helps to further determine probability of benign disease if negative. In the setting of a mass (higher suspicion of malignancy), the PET is most useful to assess mediastinal or distant areas for abnormal FDG uptake.

VI

Biopsy Options

• 1.

  Sputum cytology—not used routinely, should be considered on a case-by-case basis

• 2.

  Flexible bronchoscopy with direct biopsy or transbronchial needle aspiration (TBNA)

• 3.

  Endobronchial ultrasound–guided transbronchial biopsy (EBUS-TBNA)

• 4.

  Percutaneous fine-needle aspiration, CT guided

• 5.

  Surgical biopsy—diagnostic wedge resection via video-assisted thoracic surgery (VATS)

VII

Epithelial Tumors