A solitary pulmonary nodule is defined as a discrete, well-marginated, rounded opacity less than or equal to 3 cm in diameter that is completely surrounded by lung parenchyma, does not touch the hilum or mediastinum, and is without associated atelectasis or pleural effusion. See the images below.
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A 1.5-cm coin lesion in the left upper lobe in a patient with prior colonic carcinoma. Transthoracic needle biopsy findings confirmed this to be a met....
View Image
Mediastinal windows of the patient in the image above.
Patients with solitary pulmonary nodules are usually asymptomatic; however, solitary pulmonary nodules pose a challenge to both clinicians and patients. Whether detected serendipitously or during a routine investigation, a nodule on a chest radiograph raises several questions: Is the nodule benign or malignant? Should it be investigated or observed? Should it be surgically resected?
Most solitary pulmonary nodules are benign, but they may represent an early stage of lung cancer. Lung cancer is the leading cause of cancer death in the United States, accounting for more deaths annually than breast, colon, and prostate cancers combined. Lung cancer survival rates remain dismally low at 14% at 5 years. Early lung cancer, when the primary tumor is less than 3 cm in diameter (stage 1A), may lead to 5-year survival rates of 70-80%. Therefore, prompt diagnosis and management of early lung cancer manifesting as solitary pulmonary nodule may be the only chance for cure.
A solitary pulmonary nodule is defined as a single, discrete pulmonary opacity that is less than 3 cm in diameter, surrounded by normal lung tissue, and not associated with adenopathy or atelectasis. Lesions larger than 3 cm are considered masses and are treated as malignancies until proven otherwise.
Generally, a pulmonary nodule must reach 1 cm in diameter before it can be identified on a chest radiograph. For a malignant nodule to reach this size, approximately 30 doublings would have occurred. The average doubling time for a tumor is 120 days (range 7-590 d). A lesion at this growth rate may be present for 10 years before discovery.
A solitary pulmonary nodule may be secondary to a wide differential of causes. However, greater than 95% are malignancies (most likely primary), granulomas (most likely infectious), or benign tumors (most likely hamartoma).
Solitary pulmonary nodules are one of the most common thoracic radiographic abnormalities. Approximately 150,000 cases are detected each year as an incidental finding, either on chest radiographs or thoracic CT scans.[1] In lung cancer screening studies that enrolled people at high risk for lung cancer, the prevalence of solitary pulmonary nodules ranged from 8-51%.[2]
Approximately 40-50% of solitary pulmonary nodules are malignant. Gould et al reported after a review of the literature that most of these are adenocarcinoma (47%), followed by squamous cell carcinoma (22%); small cell lung cancer makes up only 4% of malignant solitary pulmonary nodules.[3]
Mortality/Morbidity
Most solitary pulmonary nodules are benign, but they may represent an early stage of lung cancer. Although lung cancer survival rates remain dismally low at 14% at 5 years, early lung cancer (ie, diagnosed when the primary tumor has a diameter < 3 cm [stage 1A]) can be associated with a 5-year survival rate of 70-80%. Accordingly, the only chance for cure of early lung cancer manifesting as solitary pulmonary nodule is prompt diagnosis and management.
Age
Risk of malignancy increases with age. For individuals younger than 39 years, the risk is 3%. The risk increases to 15% for individuals aged 40-49 years, to 43% for persons aged 50-59 years, and to more than 50% for persons older than 60 years.
Most patients with solitary pulmonary nodules are asymptomatic; the nodules are typically detected as an incidental finding. Approximately 20-30% of all bronchogenic carcinomas appear as solitary pulmonary nodules on initial radiographs. The following features are important when assessing whether the nodule is benign or malignant.
History of malignancy
History of smoking
Occupational risk factors for lung cancer: Exposure to asbestos, radon, nickel, chromium, vinyl chloride, and polycyclic hydrocarbons can lead to the development of a solitary pulmonary nodule.
Travel: Travel to areas with endemic mycosis (eg, histoplasmosis, coccidioidomycosis, blastomycosis) or to areas with a high prevalence of tuberculosis (TB) can lead to the development of a benign solitary pulmonary nodule.
Bearing in mind that the major distinction that must be made is between neoplastic and inflammatory lesions, solitary pulmonary nodules may have the following causes:
Laboratory studies have a limited role in the workup of solitary pulmonary nodules (SPNs).
Anemia or an elevated sedimentation rate may indicate an underlying neoplastic or infectious process.
Elevated levels of liver enzymes, alkaline phosphatase, or serum calcium may indicate metastases from a solitary bronchogenic carcinoma or extrapulmonary malignancy.
Patients who have histoplasmosis or coccidioidomycosis may have high levels of immunoglobulin G and immunoglobulin M antibodies specific to these fungi.
Because solitary pulmonary nodules are first detected on chest radiographs, the initial distinction is whether the nodule is pulmonary or extrapulmonary in nature. Findings from a lateral chest radiography, fluoroscopy, or CT scanning may help confirm the location of the nodule. Although nodules of 5 mm in diameter are occasionally visualized on chest radiographs, solitary pulmonary nodules are quite often 8-10 mm in diameter.
Chest radiographs can provide information regarding size, shape, cavitation, growth rate, and calcification pattern. All of these radiologic features can help determine whether the lesion is benign or malignant. However, none of these features is entirely specific for lung carcinoma.
CT scanning of the chest has many advantages over plain chest radiography.[4] Advantages include better resolution of nodules and detection of nodules as small as 3-4 mm. CT scan images also help better characterize the morphologic features of various lesions. Multiple nodules and regions that are difficult to assess on chest radiographs are better visualized on CT scan images. See the images below.
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A left upper lobe nodule with central lucency and poorly circumscribed margins was diagnosed as actinomycosis based on needle biopsy findings.
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CT scan of the patient presented in the image above. After needle biopsy, the presence of classic sulfur granules confirmed actinomycosis.
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A left upper lobe solitary pulmonary nodule. The differential diagnosis is large, but CT scan findings help narrow the differentials and establish the....
CT densitometry measures the attenuation coefficients of a lesion and aids detection of occult calcification. Attenuation coefficients are expressed in Hounsfield units (HU); a value of more than 185 HU has been suggested as a cutoff for benign lesions. However, prospective studies have indicated low sensitivity and specificity for CT densitometry measurements; thus, these measurements are no longer routinely used.
With regard to dynamic contrast enhancement, a greater degree of contrast enhancement on repeated measurements of attenuation indicates that the nodule is malignant. Enhancement of greater than 20 HU is associated with malignancy, whereas less than 15 HU suggests a benign lesion. A multicenter study, using a cutoff value of 15 HU, found a sensitivity and specificity of 98% and 58%.[5] Active granulomas or other infectious lesions may also enhance, thus limiting the application of this technique. However, a failure to enhance by more than 15-20 HU has greater than a 95% predictive value for benignity.
Several radiologic characteristics, both on CT and radiography (although CT is superior), may help establish the diagnosis or suggest if a lesion is benign or malignant. These include (1) size, (2) growth rate, (3) presence of calcification, (4) border characteristics, (5) internal characteristics, and (6) location.
Size: Although a well-defined nodule of smaller size that is clearly visible on chest radiographs may be calcified and benign, small lesions may very well be early-stage bronchogenic carcinoma. A lesion greater than 4 cm in diameter is very likely a bronchogenic carcinoma, although exceptions include lung abscess, Wegener's granulomatosis, lymphoma, round pneumonia, rounded atelectasis, and hydatid cyst. Midthun et al indicated that the likelihood of malignancy was 50% in nodules greater than 20 mm and 18% for those 8-20 mm in diameter. With lesions smaller than 8 mm, a sharp decline is noted, with nodules of 4-7 mm having a likelihood of malignancy of only 0.9% and those less that 3 mm only 0.2%.[6]
Rate of growth: Serial chest radiographs facilitate estimation of the growth rate of a nodule.
Growth rate refers to the doubling time of a nodule, which is doubling of the nodule volume. Because a nodule on a chest radiograph is seen as a 2-dimensional circle rather than a 3-dimensional sphere, an increase in diameter of 26% corresponds to a doubling of nodule volume.
Bronchogenic carcinoma generally doubles in 1-18 months (average 4-8 mo). Although a doubling time of less than 1 month or longer than 18 months makes bronchogenic carcinoma unlikely, it does not exclude the diagnosis completely. Important exceptions are bronchoalveolar carcinoma, which may require more than 2 years to double in size, and metastases from specific tumors (eg, osteosarcoma, choriosarcoma), which grow rapidly.[7]
In general, doubling times of less than 1 month suggest infections; doubling times of more than 18 months suggest benign processes such as granuloma, hamartoma, bronchial carcinoid, and rounded atelectasis. If a nodule remains the same size for 2 years, it is very likely benign; however, further follow-up monitoring may be indicated.
In one restrospective series, a volume doubling time of < 400 days at 3 month and 1 year followup was strongly predictive of malignancy (OR 15.6 [4.5-53.5] and 213.3 [18.7-2430.9) respectively)[8]
Calcification: Chest radiographs may demonstrate calcification, which often indicates that the lesion is benign. (The CT scan is the most sensitive technique for detection of calcification.) The 5 patterns of calcification usually observed in benign lesions are diffuse, central, laminar, concentric, and popcorn. A stippled or eccentric pattern is associated with malignancy. See the images below.
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Close-up view of a right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
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A "popcorn" calcification in the left lung nodule indicates a benign lesion or hamartoma. No further tests or observations are needed for this patient....
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Right upper lobe nodule shows peripheral calcification and high Hounsfield unit enhancement, suggesting that the lesion is a calcified benign pulmonar....
Border characteristics
A very irregular edge or corona radiata (numerous strands radiating into the surrounding lung) may indicate a bronchogenic carcinoma.
A well-defined, smooth, nonlobulated edge may indicate a benign lesion or metastasis, whereas lobulation and notching may indicate bronchogenic carcinoma.
Cavitation with a thin, smooth wall may indicate lung abscess or a benign lesion, whereas thick-walled cavitations imply an underlying malignant neoplasm. See the images below.
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Left upper lobe cavitating solitary nodule eventually identified as active pulmonary tuberculosis from percutaneous needle biopsy findings.
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Cavitating right lower lobe nodule later confirmed to be primary pulmonary lymphoma. Calcium deposits may also be present in the lesion.
The CT halo sign (ie, ground-glass attenuation surrounding a nodule on CT scan image) most commonly indicates infection with an invasive Aspergillus species. Other less common possibilities include TB, cytomegalovirus infection, or herpes simplex infections.
Internal characteristics: Several characteristics within the nodule itself can indicate a specific cause.
Demonstration of fat within the lesion is specific for a hamartoma, a benign lesion. See the images below.
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Left upper lobe 1.5-cm nodule shows negative CT scan numbers, suggesting fat in the lesion consistent with hamartoma.
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The parenchymal lesion in this CT scan demonstrates low attenuation within the lesion, indicating the presence of fat. Fat density is only observed in....
Ground-glass opacities may represent a benign lesion, such as atypical adenomatous hyperplasia, or malignancy, such as bronchoalveolar carcinoma (BAC).[3] Importantly, malignant ground-glass opacities often grow slower and may require longer follow up.[2]
Subsolid nodules (nodules with both solid and ground glass component) are frequently peripheral adenocarcinomas of the lung. Studies have demonstrated excellent correlation between the Noguchi classification of adenocarcinomas and CT findings. Specifically, atypical alveolar hyperplasia typically manifests as pure ground glass lesions less than 5cm; BAC is usually greater than 5cm; lesions with mixed solid component and ground glass correlate with adenocarcima, mixed subtype.[9]
The presence of air bronchograms within the solitary pulmonary nodule makes bronchogenic carcinoma or metastasis unlikely, although they may be observed with bronchoalveolar carcinoma or lymphoma. Invasion of the adjacent bone by the nodule is pathognomic of bronchogenic carcinoma.
Location
Nodules that are attached to pleura, vessels or fissures are likely benign[8, 10]
Positron-emission tomography
Whether positron-emission tomography (PET) scanning will be useful depends on (1) the clinical pretest probability of malignancy, (2) nodule morphology, (3) the size and position of the nodule, and (4) the scanning facility available.[11]
Because malignant nodules have increased glucose metabolism compared with benign lesions and healthy lungs, enhancement of the lesion makes it likely to be malignant. Injection of analogue 18-F-2 fluorodeoxyglucose (FDG) is used to assess the metabolic activity. FDG-PET scans may be analyzed semiquantitatively using standardized uptake values (SUVs) to normalize measurements for the patient's weight and the injected dose of radioisotope. Although visual analysis findings (depending on the experience and judgment of the nuclear medicine physician) may match SUV calculations, an SUV of less than 2.5 is considered indicative of a benign lesion.
FDG-PET scans are quite helpful in detecting mediastinal metastases, thus improving staging of noninvasive lung cancer. FDG-PET scans have several limitations because the false-positive findings occur in other metabolically active pulmonary nodules, which are either infectious or inflammatory. Tumors that have lower metabolic rates, such as carcinoid and bronchoalveolar carcinoma, may be difficult to distinguish from background activity. Finally, the FDG-PET scan has lower sensitivity for nodules smaller than 20 mm in diameter and may miss lesions smaller than 10 mm.
Several studies have reported the sensitivity, specificity, and accuracy of FDG-PET scanning to be greater than 90%, 75%, and 90%, respectively,[12] including a meta-analysis of 40 studies evaluating 1474 focal pulmonary lesions of any size.[13] FDG-PET scanning is an accurate and noninvasive imaging test for the diagnosis of pulmonary nodules and larger masses.[14] However, not much data are available for nodules smaller than 1 cm in diameter.
One study compared the diagnostic accuracy of helical dynamic CT (HDCT) scanning and integrated PET/CT scanning for pulmonary nodule characterization. The sensitivity, specificity, and accuracy for malignancy with HDCT scanning were 81% (64 of 79 nodules), 93% (37 of 40 nodules), and 85% (101 of 119 nodules), respectively, whereas the values for integrated PET/CT scanning were 96% (76 of 79 nodules), 88% (35 of 40 nodules), and 93% (111 of 119 nodules), respectively.[15] Integrated PET/CT scanning is more sensitive and accurate than HDCT scanning for malignant nodule diagnosis, making it the first-line evaluation tool for solitary pulmonary nodules. Because of the high specificity and acceptable sensitivity and accuracy of HDCT scanning, it may be a reasonable alternative if PET/CT scanning is unavailable.
PET scanning has low sensitivity in small and slow growing lesions, such as BAC and carcinoid tumors.[9] One study showed very high false negative rates (up to 100%) for BAC.[16]
Single-photon emission computed tomography
Single-photon emission computed tomography (SPECT) scanning is less expensive than PET scanning, but both modalities have comparable sensitivity and specificity. SPECT imaging is performed using a radiolabeled somatostatin-type receptor binder, technetium Tc P829. SPECT imaging has not been evaluated in a large series of patients; in a smaller series, the sensitivity fell significantly for nodules less than 20 mm in diameter.
Naalsund et al evaluated the diagnostic performances of technetium Tc 99m depreotide in differentiating benign solitary pulmonary nodules from malignant solitary pulmonary nodules.[17] They also compared the diagnostic accuracy of99m Tc with FDG-PET scanning in a prospective, multicenter trial. SPECT scanning with99m Tc depreotide revealed a sensitivity, specificity, and diagnostic accuracy of 89%, 67%, and 81%, respectively. Furthermore, in patients who underwent both99m Tc depreotide SPECT imaging and FDG-PET imaging, the sensitivity, specificity, and diagnostic accuracy were identical for both modalities.
Biopsy of solitary pulmonary nodule can be performed bronchoscopically or via transthoracic needle aspiration (TTNA).
Because the yield from bronchoscopy is only 10-20% when the nodule is less than 2 cm in diameter, bronchoscopy and transbronchial needle aspiration (TBNA) may be helpful when the lesion is either endobronchial in location or near a large airway. Prospective data from the NELSON lung cancer screening trial indicate that the sensitivity of bronchoscopy for suspicious nodules seen on CT is only 8.3%. However, if an endobronchial lesion is visualized, the sensitivity increases to 81.8%.[18] TBNA may also be helpful in sampling the mediastinal nodes. Fluoroscopy or endobronchial ultrasound can be used to localize the lesions during TBNA to increase the diagnostic yield to 70% or more.[19, 20, 21]
TTNA reportedly has an accuracy of 90-95% when the lesion is 2 cm or larger in diameter, although the diagnosis is less accurate (60-80%) in lesions smaller than 2 cm. Confirming a specific benign diagnosis is more difficult (approximately 70% accuracy); therefore, most benign lesions are characterized as nondiagnostic following TTNA. The rate of pneumothorax following TTNA is approximately 25%, with approximately 7% requiring chest intubation.[22, 23]
Lesions that have typical benign features, such as lack of change over 2 years or a benign pattern of calcification, especially in low-risk patients, do not require further workup. On the other hand, lesions that are strongly suggestive of malignancy (eg, >3 cm diameter) or those with documented growth should be referred for surgical resection.[24] Management decisions for lesions with intermediate probability (which are most lesions) are more complex. Although management varies amongst individual institutions and practitioners, several guidelines have been published.
In 2005, the Fleischner Society published guidelines[25] for follow-up imaging of solitary pulmonary nodules (SPNs). They specified different strategies based on patient risk factors and the size of the nodule
Low-risk patients
Less than or equal to 4 mm - No further investigation
4-6 mm - CT scanning at 12 months
6-8 mm - CT scanning at 6-12 months and 18-24 months
Greater than 8 mm - CT scanning at 3, 9, and 24 months; contrast-enhanced CT scanning; positron-emission tomography (PET) scanning; and/or biopsy
High-risk patients
Less than or equal to 4 mm - CT scanning at 12 months
4-6 mm - CT scanning at 6-12 months and 18-24 months
6-8 mm - CT scanning at 3–6 months, 9–12 months, and 24 months
Greater than 8 mm - Same as low-risk patients
The American College of Chest Physicians (ACCP) proposed new guidelines in 2007[3] for the management of solitary pulmonary nodules, which are summarized below.
Carefully calculate pretest probability for malignancy, either through experienced clinical judgment or through the use of a validated model, such as Bayesian analysis.[26]
Previous chest radiographs should be reviewed to determine if the lesion has been stable over 2 years. If so, no further follow up is necessary, with the exception of pure ground-glass lesions on CT scans, which can be slower growing.
For lesions with a benign pattern of calcification, further testing is not necessary.
Management of indeterminate lesions greater than 8-10 mm depends on clinical probability of malignancy, as follows:
Low probability - Serial CT scanning at 3, 6, 12, and 24 months
Intermediate probability - 18-Fluorodeoxyglucose (FDG) PET scanning, contrast-enhanced CT scanning, transthoracic needle aspiration (TTNA), and/or transbronchial needle aspiration (TBNA) (Thoracoscopic diagnosis is recommended for patients who wish to have a surgical diagnosis if the lesion is in the peripheral third of the lung.)
High probability - Surgical resection
Subcentimeter lesions - Same as Fleischner Society, as listed above
Any unequivocal growth noted during follow up - Definitive tissue diagnosis needed
Management of pure ground glass lesions or lesions with mixed ground glass and solid components is more controversial and no formal guidelines have been made. Thus careful consideration of available data and clinical judgement should be utilized on a case-by-case basis to manage these lesions.
When a lesion is likely to be malignant, surgical resection—not TTNA or observation—is often used.
The 2007 ACCP guidelines recommend that patients who have indeterminate lung nodules with a high probability of malignancy undergo thoracoscopic wedge resections if the lesion is in the peripheral third of the lung. This is because of the relatively low morbidity and mortality associated with the procedure compared with thoracotomy.[27] If frozen sections show evidence of malignancy, anatomic resection with mediastinal lymph node sampling or dissection may be performed.
Localization using methylene blue injection or wire placement has facilitated successful resection of smaller nodules with video-assisted thoracoscopic surgery (VATS). Intraoperative ultrasonography is also suggested as a means of nodule localization during VATS.[28]
For proven malignant solitary pulmonary nodule, lobectomy is preferred over wedge resection or segmentectomy because of the lower rate of recurrence and trend toward increased 5-year survival with lobectomy.[29]
Most solitary pulmonary nodules are benign, but they may represent an early stage of lung cancer. While lung cancer survival rates remain dismally low at 14% at 5 years, early lung cancer (ie, diagnosed when the primary tumor has a diameter smaller than 3 cm [stage 1A]) can be associated with a 5-year survival rate of 70-80%. Accordingly, the only chance for cure of early lung cancer manifesting as solitary pulmonary nodule is prompt diagnosis and management.
Asif Alavi, MD, Resident Physician, Department of Internal Medicine, University of California, Los Angeles, David Geffen School of Medicine, Olive View Medical Center
Disclosure: Nothing to disclose.
Coauthor(s)
Nader Kamangar, MD, FACP, FCCP, FCCM, Associate Professor of Medicine, Division of Pulmonary, Critical Care and Sleep Medicine, University of California, Los Angeles, David Geffen School of Medicine, Olive View-UCLA Medical Center; Associate Program Director, Pulmonary and Critical Care Multi-Campus Fellowship Program, Cedars-Sinai/West Los Angeles Veterans Affairs/Los Angeles Kaiser Permanente/Olive View-UCLA Medical Center; Site Director, Pulmonary/Critical Care Fellowship Program, Olive View-UCLA Medical Center
Disclosure: Nothing to disclose.
Specialty Editors
Stephen P Peters, MD, PhD, FACP, FAAAAI, FCCP, FCPP, Professor of Genomics and Personalized Medicine Research, Internal Medicine, and Pediatrics, Associate Director, Center for Genomics and Personalized Medicine Research, Director of Research, Section on Pulmonary, Critical Care, Allergy and Immunologic Diseases, Wake Forest University School of Medicine
Disclosure: See below for list of all activities None None
Francisco Talavera, PharmD, PhD, Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference
Disclosure: Medscape Salary Employment
Timothy D Rice, MD, Associate Professor, Departments of Internal Medicine and Pediatrics and Adolescent Medicine, St Louis University School of Medicine
Disclosure: Nothing to disclose.
Chief Editor
Zab Mosenifar, MD, Director, Division of Pulmonary and Critical Care Medicine, Director, Women's Guild Pulmonary Disease Institute, Professor and Executive Vice Chair, Department of Medicine, Cedars Sinai Medical Center, University of California, Los Angeles, David Geffen School of Medicine
Disclosure: Nothing to disclose.
Additional Contributors
The authors and editors of eMedicine gratefully acknowledge the contributions of previous authors, Sat Sharma, MD, FRCPC, and Sri R Navaratnam, MBBS, PhD, FRCPC, to the development and writing of this article.
Midthun DE, Swensen SJ, Jett JR, Hartman TE. Evaluation of nodules detected by screening for lung cancer with low dose spiral computed tomography. Lung Cancer. Aug 2003;41 (suppl 2):S40.
Chhajed PN, Bernasconi M, Gambazzi F. Combining bronchoscopy and positron emission tomography for the diagnosis of the small pulmonary nodule < or = 3 cm. Chest. Nov 2005;128(5):3558-64.
Herder GJ, van Tinteren H, Golding RP. Clinical prediction model to characterize pulmonary nodules: validation and added value of 18F-fluorodeoxyglucose positron emission tomography. Chest. Oct 2005;128(4):2490-6.
A 1.5-cm coin lesion in the left upper lobe in a patient with prior colonic carcinoma. Transthoracic needle biopsy findings confirmed this to be a metastatic deposit.
Mediastinal windows of the patient in the image above.
A left upper lobe nodule with central lucency and poorly circumscribed margins was diagnosed as actinomycosis based on needle biopsy findings.
CT scan of the patient presented in the image above. After needle biopsy, the presence of classic sulfur granules confirmed actinomycosis.
A left upper lobe solitary pulmonary nodule. The differential diagnosis is large, but CT scan findings help narrow the differentials and establish the diagnosis.
Close-up view of a right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
A "popcorn" calcification in the left lung nodule indicates a benign lesion or hamartoma. No further tests or observations are needed for this patient.
Right upper lobe nodule shows peripheral calcification and high Hounsfield unit enhancement, suggesting that the lesion is a calcified benign pulmonary nodule.
Left upper lobe cavitating solitary nodule eventually identified as active pulmonary tuberculosis from percutaneous needle biopsy findings.
Cavitating right lower lobe nodule later confirmed to be primary pulmonary lymphoma. Calcium deposits may also be present in the lesion.
Left upper lobe 1.5-cm nodule shows negative CT scan numbers, suggesting fat in the lesion consistent with hamartoma.
The parenchymal lesion in this CT scan demonstrates low attenuation within the lesion, indicating the presence of fat. Fat density is only observed in hamartoma and lipoid pneumonia. The likely diagnosis is hamartoma.
Right upper lobe nodule shows peripheral calcification and high Hounsfield unit enhancement, suggesting that the lesion is a calcified benign pulmonary nodule.
A 1.5-cm coin lesion in the left upper lobe in a patient with prior colonic carcinoma. Transthoracic needle biopsy findings confirmed this to be a metastatic deposit.
Mediastinal windows of the patient in the image above.
Right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
Close-up view of a right lower lobe nodule demonstrating central calcification. The most likely diagnosis is histoplasmosis.
Left upper lobe cavitating solitary nodule eventually identified as active pulmonary tuberculosis from percutaneous needle biopsy findings.
A left upper lobe nodule with central lucency and poorly circumscribed margins was diagnosed as actinomycosis based on needle biopsy findings.
CT scan of the patient presented in the image above. After needle biopsy, the presence of classic sulfur granules confirmed actinomycosis.
A right lower lobe solitary pulmonary nodule later identified to be a hamartoma.
Wedge-shaped peripheral (pleural based) density observed secondary to pulmonary infarction (pulmonary embolism). This is termed the Hampton hump.
Left upper lobe 1.5-cm nodule shows negative CT scan numbers, suggesting fat in the lesion consistent with hamartoma.
A left upper lobe solitary pulmonary nodule. The differential diagnosis is large, but CT scan findings help narrow the differentials and establish the diagnosis.
Cavitating right lower lobe nodule later confirmed to be primary pulmonary lymphoma. Calcium deposits may also be present in the lesion.
This left lower lobe carcinoid tumor was quite bloody after a percutaneous needle biopsy was performed.
A lateral radiograph of the case in the image above.
CT scan of the patient in the previous 2 images shows a well-circumscribed lesion.
A "popcorn" calcification in the left lung nodule indicates a benign lesion or hamartoma. No further tests or observations are needed for this patient.
A 1.5-cm right upper lobe nodule on CT scan was determined to be a benign fibrous lesion on needle biopsy. A follow-up at 2 years showed no change in the size of this lesion.
The parenchymal lesion in this CT scan demonstrates low attenuation within the lesion, indicating the presence of fat. Fat density is only observed in hamartoma and lipoid pneumonia. The likely diagnosis is hamartoma.
This patient has a low risk for the right upper lobe nodule to be malignant; therefore, continued observation with repeat chest radiographs to establish a growth pattern is the best treatment option.
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