150,000 detected per year with one to two nodules found on every 1,000 chest x-rays.
Most malignant (60-80%).
Two criteria of benignity are benign calcification pattern and lack of growth.
Approximately 23% of patients greater than age 60 years who undergo a screening chest CT have pulmonary nodules identified.
Of patients screened with a CT scan of the thorax only 2.7% over the age of 60 years and 1.1% of those over the age of 40 will have a malignancy.
In evaluating a tumor nodule for possible malignancy considerations include: the size, density (solid, subsolid, or mixed), the rate of change in size and density overtime, the shape (round, ovoid, or irregular, with smooth, lobulated, or speculated borders), the location (peripheral or central), and the patient’s cancer risk based on age, environmental exposures, and participation in screening.
Neoplastic nodules vary in histological characteristics and biologic aggressiveness.
Subsequent annual screening CT scans (after an initial negative screening scan of the chest) identify pulmonary nodules in 2.5% of patients and identify malignancies in 0.6% of patients.
Combination of percutaneous needle aspiration biopsy and transbronchial biopsy have a sensitivity and specificity rate of 95% ad 99% in diagnosing such lesions.
Repeat needle biopsy combined with clinical observation is a reliable method for following such lesions to determine the benign or malignant nature of solitary pulmonary nodules approaching 100% accuracy.
Premalignant neoplasms, are typically small and subsolid.
Carcinoma in situ lesions are usually larger and subsolid or solid.
The most common malignant, pulmonary nodule is adenocarcinoma, which can be so solid, mixed or subsolid.
Adenocarcinoma tends to grow more slowly than other malignancies, and is a more frequent incidental finding.
Carcinoid, tumors, typically ate spherical or ovoid, and have well-defined borders that are sometimes lobulated.
Atypical carcinoid tumors have the appearance of traditional lung cancers, with irregular shape and ill-defined, spiculated borders.
Large cell neuroendocrine carcinoma of the lung is often indistinguishable from any non-small cell lung cancer on imaging.
Small cell lung cancers usually does not manifest as a pulmonary nodular and classically manifests a bulky mess with hilar lymphadenopathy.
Metastatic lesions are well, circumscribed, round, and peripherally located.
The most common cancers that result in metastatic pulmonary nodules, include lung cancer, originating in another part of the lung, colorectal, cancer, renal, carcinoma, pancreatic carcinoma, breast, cancer, and testicular cancer.