Pediatric Pulmonology 50:456–459 (2015)
Natural History of Incidental Pulmonary Nodules in Children Dagnachew Assefa,
MD
and Arthur B. Atlas,
MD
Summary. RATIONALE: As there are no evidence based guidelines for the diagnosis and/or management of pulmonary nodules in children, there is an over reliance on the adult based algorithms when dealing with pulmonary nodules in children. We present our experience of pediatric patients evaluated for incidentally found pulmonary nodules. METHODS: Retrospective chart review of patients diagnosed with a pulmonary nodule and evaluated at Goryeb Children’s Hospital between January 2000 and December 2012. Primary outcome: change in the size of the pulmonary nodule between the initial and follow-up imaging. RESULTS: Thirty six patients with pulmonary nodule (21 male/15 female; Median [range] age 15 [5–20] years.) were included in the study. Chest CT was obtained for respiratory symptoms and/or abnormal chest radiograph in 19 (52%). Nine pulmonary nodules (25%) were identified on abdominal CT obtained for abdominal symptoms. A total of 46 nodules were identified in 36 patients. Nine of the pulmonary nodules (9 patients) were 4 mm in size, 37 of the pulmonary nodules (27 patients) were >4 mm in size. Twenty-two of the 27 (81%) patients with nodule size >4 mm had follow-up CT: 14 nodules (54%) remained unchanged in size, 5 nodules (19%) decreased in size, and 7 nodules (27%) were not detected. CONCLUSION: Our review of 36 patients with pulmonary nodules shows no obvious growth of the nodules over the study period, suggesting low risk of malignancy. Routine follow-up chest computer tomography using ACCP/Fleischner Society guidelines may not apply in children without known malignancy. Pediatr Pulmonol. 2015;50:456–459. ß 2014 Wiley Periodicals, Inc.
Key words: Pulmonary nodule; fleischner society guideline; children. Funding source: None reported.
INTRODUCTION
A pulmonary nodule is a radiologic abnormality that is most often detected incidentally by chest radiograph or computer tomography (CT) obtained for other reasons. Pulmonary nodules are increasingly detected with the widespread use of CT.1 It is estimated that a pulmonary nodule is detected on 0.1–0.2 percent of all chest radiographs2 and accounts for approximately 150,000 nodules identified each year in adults in the US.3 Most pulmonary nodules are benign, but in adults nodules may represent a primary or secondary malignancy, and therefore require further evaluation. Guidelines for the management of pulmonary nodules in adults have been published.4,5 These guidelines were developed based on findings of several CT lung screening studies performed on adult populations (age >35 years). The recommendation for follow-up is determined on the basis of nodule size (Table 1) and the patients’ risk for malignancy. Low-risk patients are those with minimal or absent smoking history, or other known risk factors, while high-risk patients have a history of smoking or have other known risk factors.4,5 As there are no guidelines for evaluating children with pulmonary nodules, radiologists who interpret the chest computer tomography scans of children are likely to use ß 2014 Wiley Periodicals, Inc.
the adult recommendations.6 The efficacy, and risks/ benefits of these guidelines in pediatric patients have not been studied. Currently there are no evidence based guidelines or algorithms for the diagnosis and/or management of pulmonary nodules in children. We present our experience with 36 patients who were evaluated for pulmonary nodules which were found incidentally on chest radiographs or chest CT between January 2000 and December 2012.
Respiratory Center for Children, Goryeb Children’s Hospital, Atlantic Health System, Morristown, New Jersey. Conflict of interest: None.
Correspondence to: Dagnachew Assefa, MD, Respiratory Center for Children, Goryeb Children’s Hospital, 100 Madison Avenue, Box #107, Morristown, NJ 07960, E-mail: [email protected] Received 31 May 2014; Revised 23 September 2014; Accepted 12 October 2014. DOI 10.1002/ppul.23141 Published online 21 November 2014 in Wiley Online Library (wileyonlinelibrary.com).
Incidental Pulmonary Nodules in Children
457
TABLE 1— Guidelines for Management of Newly Detected Indeterminate Nodule in Persons 35 Years of Age or Older According to the Fleischner Society5 Low-risk patients1
High-risk patients2
4 mm >4–6 >6–8
No follow-up CT scan at 12 months. If stable, no further follow-up CT scan at 6–12 months, then at 18–24 months if stable
>8
Follow-up CT at around 3, 9, and 24 months, dynamic contrast-enhanced CT, PET, and/or biopsy
CT scan at 12 months. If stable, no further follow-up CT scan at 6–12 months, then at 18–24 months if stable CT scan at 3–6 months, then at 9–12 months and at 24 months if stable Same as for low-risk patient
Nodule size mm
1 2
Minimal or absent history of smoking and of other known risk factors. History of smoking or of other known risk factors.
METHODS Study Design and Analyses
This study is an Institutional Review Board approved retrospective chart review of patients diagnosed with a pulmonary nodule and evaluated at Goryeb Children’s Hospital between January 2000 and December 2012. A computerized data base was used to identify all patients evaluated for a pulmonary nodule. Patients were excluded if they had any type of a known malignancy. Data regarding demographics, PPD status, smoke exposure, and indications and type of initial imaging were collected. The primary outcome of the study was the change in the size of the pulmonary nodule between the initial imaging and follow-up imaging. When more than one nodule was detected in a single subject, each nodule is considered individually when analyzing the data. Descriptive statistics were calculated using the median and inter-quartile range for continuous variables. Percentages were used to describe categorical variables. The differences in nodule size from baseline (initial imaging) to follow-up imaging were analyzed using Student paired t tests. If the nodule is not detected on subsequent imaging a Zero was entered as the nodule size.
patients) were 4 mm in size, thirty-seven of the pulmonary nodules (27 patients) were >4 mm in size (Table 3). In 11 of the 29 patients (38%) nodules were detected in both chest radiograph and chest CT. The location of the nodules is shown in Table 4. Twenty-two of the 27 (81%) patients with nodule size >4 mm (total of 26 nodules) had at least two computer tomography scans of the chest done 3–12 months apart. The temporal change in the appearance of the pulmonary nodules on computer tomography took three different forms (Fig. 1). Fourteen nodules (54%) remained unchanged in size and density, five nodules (19%) decreased in size, and seven of the nodules (27%) were not detected on the follow up chest CT DISCUSSION
The results of this study show that incidental pulmonary nodules in children tend to remain stable or disappear on follow-up imaging. It is not uncommon to find incidental pulmonary nodules in children being evaluated with imaging studies for unrelated pulmonary and non-pulmonary symptoms. Currently there are no pediatric based guidelines for evaluation or management of pulmonary nodules. Therefore there is an over reliance on the adult based guidelines and algorithms when
RESULTS
Thirty six patients with pulmonary nodule were included in the study. There were 21 males, and 15 females, with a median age of 15 (5–20) years. Chest CT was obtained for respiratory symptoms and/or abnormal chest radiograph in 19 (52%), and for variable reasons in the other 48% as outlined in Table 2. Nine pulmonary nodules (25%) were identified on abdominal CT obtained for abdominal symptoms. PPD was positive in one patient (3%). Nine patients (25%) were exposed to cigarette smoke; 5 sec hand smoke, and four patients smoked. Six patients (16.7%) had a history of asthma. A total of 46 nodules (range 2–11 mm) were identified in 36 patients. Twenty-eight patients (78%) had a solitary nodule, six patients (17%) had 2 nodules, and two patients (6%) had 3 nodules. Nine of the pulmonary nodules (9
TABLE 2— Initial Indications for Computer Tomography of the Chest
Recurrent bronchitis Unexplained shortness of breath Chronic cough Chest pain Abnormal chest radiograph Abdominal CT for abdominal Pain Neck mass MVA Vocal cord paralysis Costal osteoma Total
Number
Percent
2 5 2 3 7 9 1 5 1 1 36
5.6 13.9 5.6 8.3 19.4 25.0 2.8 13.9 2.8 2.8 100
MVA, Motor vehicle accident; CT, computer tomography.
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Assefa and Atlas
TABLE 3— Comparison of the Results of Computer Tomography of the Chest (CT) and Chest Radiograph. Total of 36 Patients (46 Nodules)
Size of nodule (mm)
Nodule seen on both CT and chest radiograph patient (nodules)
4 >4–8 >8 Total
1 8 2 11
Nodule seen on chest CT but not chest radiograph patients (nodules)
(1) (11) (2) (14)
5 11 2 18
(5) (16) (3) (24)
No chest radiograph patients (nodules) 3 (3) 4 (5) 0 7 (8)
evaluating pulmonary nodules in children. The wide spread use of computed tomography for imaging of the chest and abdomen in children has led to an increase in the number of incidentally detected pulmonary nodules. The significance of these nodules and their natural history in children is often uncertain. To our knowledge, there are no studies evaluating the natural history of pulmonary nodules incidentally detected in children with nonmalignant disease. There are relatively few articles in the literature describing the CT features of lung nodules in children, and these articles base results exclusively on studies in children with known extrapulmonary malignancies. Several of these studies have shown that most of the pulmonary nodules detected by computer tomography in children with malignancies were benign lesions, and possibly due to post-chemotherapy fibrotic nodules or benign granulomas.7,8 In contrast to adults, the CT features of pulmonary nodules have not been extensively evaluated in children. Certain CT characteristics of a pulmonary nodule, such as size and nodule margins, are thought to be indicative of malignancy in adults but probably do not apply to children. McCarville et al.6 evaluated 41 children with malignant solid tumors and found that lung nodules smaller than 5 mm were as likely to be malignant as larger ones, and that pulmonary nodules with well-defined margins were more often malignant than benign. Silva et al.9 studied 111 infants and children with lung nodules identified at diagnosis of an extrapulmonary malignancy. The authors found that none of the CT nodule characteristics i.e., location, number, distribution, CT attenuation, shape,
TABLE 4— Location of the Pulmonary Nodules Nodule Size 4 mm
RUL
RML
RLL
LUL
LLL
3 6
0 2
2 10
3 11
1 8
RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe; LUL, left upper lobe; LLL, left lower lobe.
Pediatric Pulmonology
Fig. 1. Temporal change in computer tomography appearance of pulmonary nodules (computer tomography of the chest done 3–12 months apart).
margins, calcification, and size, was able to differentiate malignant from benign nodules in the 27 patients who underwent tissue biopsy. In contrast, Grampp et al.10 found that in children with known extrapulmonary malignancies, solitary lung nodules smaller than 5 mm, especially those with unsharp margins, tended to remain stable on followup CT, whereas nodules larger than 5 mm, especially when multiple and with sharp margins, were almost always malignant. We found no articles, in the English language literature, regarding the natural history of pulmonary nodules found incidentally in children with non-malignant disease. Our study, albeit limited, showed that these incidental nodules are highly likely to remain stable, get smaller or disappear completely on follow-up imaging. Most radiologists who interpret the chest computer tomography scans of children, practice either in general pediatric or combined adult-pediatric settings,6 and are likely to follow either the Fleischner or ACCP guideline. For patients less than 35 years of age, the Fleischner society guidelines5 recommend that unless there is a known primary cancer, multiple follow-up CT studies for small (3–5 mm) incidentally detected nodules should not be instituted. In such cases, the guideline suggests a single low-dose follow-up CT scan in 6–12 months. However, this recommendation, which is based on expert opinion, is surprisingly not followed by the reading radiologists11,12 or practicing pediatric pulmonologists.13 A survey of the members of the Society of Thoracic Radiology12 showed that, in general, radiologists tend to be overly aggressive in follow-up strategies with nearly 50% recommending a follow-up examination in 3 to 6 months even for small (3–5 mm) pulmonary nodules identified on computer tomography in low-risk individuals. These recommendations result in most children with pulmonary nodules, who
Incidental Pulmonary Nodules in Children
are at low risk for malignancy getting repeated computer tomography scans. Similarly, approximately 48% of pediatric pulmonologists surveyed recommend either a 3–6 month (21%) or 12 month (27%) CT follow-up for a small (4-mm-diameter, noncalcified) nodule found incidentally.13 The Fleischner5 and ACCP4 guidelines were developed based on findings of several CT lung screening studies performed on older patient populations. Therefore, these recommendations cannot be reliably extrapolated to children. Moreover, the pretest probability that a pulmonary nodule in an otherwise healthy child is malignant is extremely low. Hence, using these guidelines in children results in their receiving increased radiation, without changing the likelihood of detection of lung cancer or a metastatic lesion. Children are particularly sensitive to radiation, and their young age allows many years in the future for cancers to develop. The approximately 4 million pediatric CT scans of the head, abdomen/pelvis, chest, or spine performed in the US each year are projected to cause 4,870 future cancers.14 It is suggested that a third of pediatric CT scans are unnecessary and that eliminating them could potentially reduce the number of CTattributable cancers by a third.15 In summary, our review of 36 patients with pulmonary nodules shows no obvious growth or enlargement of the nodules over the study period, suggesting low risk of malignancy. Routine follow-up CT tomography using ACCP/Fleischner Society guidelines may not apply in children without known malignancy. In low risk children with sub-centimetric nodules (4 mm in size on the initial computer tomography did not return for followup imaging. Larger studies which include different geographic locations are needed to verify our findings.
459
REFERENCES 1. Soubani AO. The evaluation management of the solitary pulmonary nodule. Postgrad Med 2008;84:459–466. 2. Holin SM, Dwork RE, Glaser S, Rikli AE, Stocklen JB. Solitary pulmonary nodules found in a community-wide chest roentgenographic survey; a five-year follow-up study. Am Rev Tuberc 1959; 79:427–439. 3. Swensen SJ, Silverstein MD, Edell ES, Trastek VF, Aughenbaugh GL, Ilstrup DM, Schleck CD. Solitary pulmonary nodules: clinical prediction model versus physicians. Mayo Clin Proc 1999;74: 319–329. 4. Gould MK, Fletcher J, Iannettoni MD, Lynch WR, Midthun DE, Naidich DP, Ost DE; American College of Chest Physicians. Evaluation of patients with pulmonary nodules: when is it lung cancer?: ACCP evidence-based clinical practice guidelines (2nd edition). Chest 2007;132:108S–130S. 5. MacMahon H, Austin JH, Gamsu G, Herold CJ, Jett JR, Naidich DP, Patz EF Jr, Swensen SJ; Fleischner Society. Guidelines for management of small pulmonary nodules detected on CT scans: a statement from the Fleischner Society. Radiology 2005;237: 395–400. 6. McCarville MB, Lederman HM, Santana VM, Daw NC, Shochat SJ, Li CS, Kaufman RA. Distinguishing benign from malignant pulmonary nodules with helical chest CT in children with malignant solid tumors. Radiology 2006;239:514–520. 7. Cohen M, Grosfeld J, Baehner R, Weetman R. Lung CT for detection of metastases: solid tissue neoplasms in children. AJR Am J Roentgenol 1982;139:895–898. 8. Robertson PL, Boldt DW, De Campo JF. Paediatric pulmonary nodules: a comparison of computed tomography, thoracotomy findings and histology. Clin Radiol 1988;39:607–610. 9. Silva CT, Amaral JG, Moineddin R, Doda W, Babyn PS. CT characteristics of lung nodules present at diagnosis of extrapulmonary malignancy in children. Am J Roentgenol 2010;194: 772–778. 10. Grampp S, Bankier AA, Zoubek A, Wiesbauer P, Schroth B, Henk CB, Grois N, Mostbeck GH. Spiral CT of the lung in children with malignant extra-thoracic tumors: distribution of benign vs malignant pulmonary nodules. Eur Radiol 2000;10:1318–1322. 11. Jeudy J, White CS, Munden RF, Boiselle PM. Management of small (3–5 mm) pulmonary nodules at chest CT: global survey of thoracic radiologists. Radiology 2008;247:847–853. 12. Munden RF, Hess KR. “Ditzels” on Chest CT. Am J Roentgenol 2001;176:1363–1369. 13. Assefa D, Atlas AB. Management of pulmonary nodules in pediatric patients. A survey of practicing pediatric pulmonologist in the USA. Am J Respir Crit Care Mrd 2014;189:A1801. 14. Miglioretti DL, Johnson E, Williams A, Greenlee RT, Weinmann S, Solberg LI, Feigelson HS, Roblin D, Flynn MJ, Vanneman N, Smith-Bindman R. The use of computed tomography in pediatrics and the associated radiation exposure and estimated cancer risk. JAMA Pediatr 2013;167:700–707. 15. Slovis TL. Children computed tomography radiation dose, and the As Low As Reasonably Achievable (ALARA) concept. Pediatrics 2003;112:971–972.
Pediatric Pulmonology
Natural History of Incidental Pulmonary Nodules in Children Dagnachew Assefa,
MD
and Arthur B. Atlas,
MD
Summary. RATIONALE: As there are no evidence based guidelines for the diagnosis and/or management of pulmonary nodules in children, there is an over reliance on the adult based algorithms when dealing with pulmonary nodules in children. We present our experience of pediatric patients evaluated for incidentally found pulmonary nodules. METHODS: Retrospective chart review of patients diagnosed with a pulmonary nodule and evaluated at Goryeb Children’s Hospital between January 2000 and December 2012. Primary outcome: change in the size of the pulmonary nodule between the initial and follow-up imaging. RESULTS: Thirty six patients with pulmonary nodule (21 male/15 female; Median [range] age 15 [5–20] years.) were included in the study. Chest CT was obtained for respiratory symptoms and/or abnormal chest radiograph in 19 (52%). Nine pulmonary nodules (25%) were identified on abdominal CT obtained for abdominal symptoms. A total of 46 nodules were identified in 36 patients. Nine of the pulmonary nodules (9 patients) were 4 mm in size, 37 of the pulmonary nodules (27 patients) were >4 mm in size. Twenty-two of the 27 (81%) patients with nodule size >4 mm had follow-up CT: 14 nodules (54%) remained unchanged in size, 5 nodules (19%) decreased in size, and 7 nodules (27%) were not detected. CONCLUSION: Our review of 36 patients with pulmonary nodules shows no obvious growth of the nodules over the study period, suggesting low risk of malignancy. Routine follow-up chest computer tomography using ACCP/Fleischner Society guidelines may not apply in children without known malignancy. Pediatr Pulmonol. 2015;50:456–459. ß 2014 Wiley Periodicals, Inc.
Key words: Pulmonary nodule; fleischner society guideline; children. Funding source: None reported.
INTRODUCTION
A pulmonary nodule is a radiologic abnormality that is most often detected incidentally by chest radiograph or computer tomography (CT) obtained for other reasons. Pulmonary nodules are increasingly detected with the widespread use of CT.1 It is estimated that a pulmonary nodule is detected on 0.1–0.2 percent of all chest radiographs2 and accounts for approximately 150,000 nodules identified each year in adults in the US.3 Most pulmonary nodules are benign, but in adults nodules may represent a primary or secondary malignancy, and therefore require further evaluation. Guidelines for the management of pulmonary nodules in adults have been published.4,5 These guidelines were developed based on findings of several CT lung screening studies performed on adult populations (age >35 years). The recommendation for follow-up is determined on the basis of nodule size (Table 1) and the patients’ risk for malignancy. Low-risk patients are those with minimal or absent smoking history, or other known risk factors, while high-risk patients have a history of smoking or have other known risk factors.4,5 As there are no guidelines for evaluating children with pulmonary nodules, radiologists who interpret the chest computer tomography scans of children are likely to use ß 2014 Wiley Periodicals, Inc.
the adult recommendations.6 The efficacy, and risks/ benefits of these guidelines in pediatric patients have not been studied. Currently there are no evidence based guidelines or algorithms for the diagnosis and/or management of pulmonary nodules in children. We present our experience with 36 patients who were evaluated for pulmonary nodules which were found incidentally on chest radiographs or chest CT between January 2000 and December 2012.
Respiratory Center for Children, Goryeb Children’s Hospital, Atlantic Health System, Morristown, New Jersey. Conflict of interest: None.
Correspondence to: Dagnachew Assefa, MD, Respiratory Center for Children, Goryeb Children’s Hospital, 100 Madison Avenue, Box #107, Morristown, NJ 07960, E-mail: [email protected] Received 31 May 2014; Revised 23 September 2014; Accepted 12 October 2014. DOI 10.1002/ppul.23141 Published online 21 November 2014 in Wiley Online Library (wileyonlinelibrary.com).
Incidental Pulmonary Nodules in Children
457
TABLE 1— Guidelines for Management of Newly Detected Indeterminate Nodule in Persons 35 Years of Age or Older According to the Fleischner Society5 Low-risk patients1
High-risk patients2
4 mm >4–6 >6–8
No follow-up CT scan at 12 months. If stable, no further follow-up CT scan at 6–12 months, then at 18–24 months if stable
>8
Follow-up CT at around 3, 9, and 24 months, dynamic contrast-enhanced CT, PET, and/or biopsy
CT scan at 12 months. If stable, no further follow-up CT scan at 6–12 months, then at 18–24 months if stable CT scan at 3–6 months, then at 9–12 months and at 24 months if stable Same as for low-risk patient
Nodule size mm
1 2
Minimal or absent history of smoking and of other known risk factors. History of smoking or of other known risk factors.
METHODS Study Design and Analyses
This study is an Institutional Review Board approved retrospective chart review of patients diagnosed with a pulmonary nodule and evaluated at Goryeb Children’s Hospital between January 2000 and December 2012. A computerized data base was used to identify all patients evaluated for a pulmonary nodule. Patients were excluded if they had any type of a known malignancy. Data regarding demographics, PPD status, smoke exposure, and indications and type of initial imaging were collected. The primary outcome of the study was the change in the size of the pulmonary nodule between the initial imaging and follow-up imaging. When more than one nodule was detected in a single subject, each nodule is considered individually when analyzing the data. Descriptive statistics were calculated using the median and inter-quartile range for continuous variables. Percentages were used to describe categorical variables. The differences in nodule size from baseline (initial imaging) to follow-up imaging were analyzed using Student paired t tests. If the nodule is not detected on subsequent imaging a Zero was entered as the nodule size.
patients) were 4 mm in size, thirty-seven of the pulmonary nodules (27 patients) were >4 mm in size (Table 3). In 11 of the 29 patients (38%) nodules were detected in both chest radiograph and chest CT. The location of the nodules is shown in Table 4. Twenty-two of the 27 (81%) patients with nodule size >4 mm (total of 26 nodules) had at least two computer tomography scans of the chest done 3–12 months apart. The temporal change in the appearance of the pulmonary nodules on computer tomography took three different forms (Fig. 1). Fourteen nodules (54%) remained unchanged in size and density, five nodules (19%) decreased in size, and seven of the nodules (27%) were not detected on the follow up chest CT DISCUSSION
The results of this study show that incidental pulmonary nodules in children tend to remain stable or disappear on follow-up imaging. It is not uncommon to find incidental pulmonary nodules in children being evaluated with imaging studies for unrelated pulmonary and non-pulmonary symptoms. Currently there are no pediatric based guidelines for evaluation or management of pulmonary nodules. Therefore there is an over reliance on the adult based guidelines and algorithms when
RESULTS
Thirty six patients with pulmonary nodule were included in the study. There were 21 males, and 15 females, with a median age of 15 (5–20) years. Chest CT was obtained for respiratory symptoms and/or abnormal chest radiograph in 19 (52%), and for variable reasons in the other 48% as outlined in Table 2. Nine pulmonary nodules (25%) were identified on abdominal CT obtained for abdominal symptoms. PPD was positive in one patient (3%). Nine patients (25%) were exposed to cigarette smoke; 5 sec hand smoke, and four patients smoked. Six patients (16.7%) had a history of asthma. A total of 46 nodules (range 2–11 mm) were identified in 36 patients. Twenty-eight patients (78%) had a solitary nodule, six patients (17%) had 2 nodules, and two patients (6%) had 3 nodules. Nine of the pulmonary nodules (9
TABLE 2— Initial Indications for Computer Tomography of the Chest
Recurrent bronchitis Unexplained shortness of breath Chronic cough Chest pain Abnormal chest radiograph Abdominal CT for abdominal Pain Neck mass MVA Vocal cord paralysis Costal osteoma Total
Number
Percent
2 5 2 3 7 9 1 5 1 1 36
5.6 13.9 5.6 8.3 19.4 25.0 2.8 13.9 2.8 2.8 100
MVA, Motor vehicle accident; CT, computer tomography.
Pediatric Pulmonology
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Assefa and Atlas
TABLE 3— Comparison of the Results of Computer Tomography of the Chest (CT) and Chest Radiograph. Total of 36 Patients (46 Nodules)
Size of nodule (mm)
Nodule seen on both CT and chest radiograph patient (nodules)
4 >4–8 >8 Total
1 8 2 11
Nodule seen on chest CT but not chest radiograph patients (nodules)
(1) (11) (2) (14)
5 11 2 18
(5) (16) (3) (24)
No chest radiograph patients (nodules) 3 (3) 4 (5) 0 7 (8)
evaluating pulmonary nodules in children. The wide spread use of computed tomography for imaging of the chest and abdomen in children has led to an increase in the number of incidentally detected pulmonary nodules. The significance of these nodules and their natural history in children is often uncertain. To our knowledge, there are no studies evaluating the natural history of pulmonary nodules incidentally detected in children with nonmalignant disease. There are relatively few articles in the literature describing the CT features of lung nodules in children, and these articles base results exclusively on studies in children with known extrapulmonary malignancies. Several of these studies have shown that most of the pulmonary nodules detected by computer tomography in children with malignancies were benign lesions, and possibly due to post-chemotherapy fibrotic nodules or benign granulomas.7,8 In contrast to adults, the CT features of pulmonary nodules have not been extensively evaluated in children. Certain CT characteristics of a pulmonary nodule, such as size and nodule margins, are thought to be indicative of malignancy in adults but probably do not apply to children. McCarville et al.6 evaluated 41 children with malignant solid tumors and found that lung nodules smaller than 5 mm were as likely to be malignant as larger ones, and that pulmonary nodules with well-defined margins were more often malignant than benign. Silva et al.9 studied 111 infants and children with lung nodules identified at diagnosis of an extrapulmonary malignancy. The authors found that none of the CT nodule characteristics i.e., location, number, distribution, CT attenuation, shape,
TABLE 4— Location of the Pulmonary Nodules Nodule Size 4 mm
RUL
RML
RLL
LUL
LLL
3 6
0 2
2 10
3 11
1 8
RUL, right upper lobe; RML, right middle lobe; RLL, right lower lobe; LUL, left upper lobe; LLL, left lower lobe.
Pediatric Pulmonology
Fig. 1. Temporal change in computer tomography appearance of pulmonary nodules (computer tomography of the chest done 3–12 months apart).
margins, calcification, and size, was able to differentiate malignant from benign nodules in the 27 patients who underwent tissue biopsy. In contrast, Grampp et al.10 found that in children with known extrapulmonary malignancies, solitary lung nodules smaller than 5 mm, especially those with unsharp margins, tended to remain stable on followup CT, whereas nodules larger than 5 mm, especially when multiple and with sharp margins, were almost always malignant. We found no articles, in the English language literature, regarding the natural history of pulmonary nodules found incidentally in children with non-malignant disease. Our study, albeit limited, showed that these incidental nodules are highly likely to remain stable, get smaller or disappear completely on follow-up imaging. Most radiologists who interpret the chest computer tomography scans of children, practice either in general pediatric or combined adult-pediatric settings,6 and are likely to follow either the Fleischner or ACCP guideline. For patients less than 35 years of age, the Fleischner society guidelines5 recommend that unless there is a known primary cancer, multiple follow-up CT studies for small (3–5 mm) incidentally detected nodules should not be instituted. In such cases, the guideline suggests a single low-dose follow-up CT scan in 6–12 months. However, this recommendation, which is based on expert opinion, is surprisingly not followed by the reading radiologists11,12 or practicing pediatric pulmonologists.13 A survey of the members of the Society of Thoracic Radiology12 showed that, in general, radiologists tend to be overly aggressive in follow-up strategies with nearly 50% recommending a follow-up examination in 3 to 6 months even for small (3–5 mm) pulmonary nodules identified on computer tomography in low-risk individuals. These recommendations result in most children with pulmonary nodules, who
Incidental Pulmonary Nodules in Children
are at low risk for malignancy getting repeated computer tomography scans. Similarly, approximately 48% of pediatric pulmonologists surveyed recommend either a 3–6 month (21%) or 12 month (27%) CT follow-up for a small (4-mm-diameter, noncalcified) nodule found incidentally.13 The Fleischner5 and ACCP4 guidelines were developed based on findings of several CT lung screening studies performed on older patient populations. Therefore, these recommendations cannot be reliably extrapolated to children. Moreover, the pretest probability that a pulmonary nodule in an otherwise healthy child is malignant is extremely low. Hence, using these guidelines in children results in their receiving increased radiation, without changing the likelihood of detection of lung cancer or a metastatic lesion. Children are particularly sensitive to radiation, and their young age allows many years in the future for cancers to develop. The approximately 4 million pediatric CT scans of the head, abdomen/pelvis, chest, or spine performed in the US each year are projected to cause 4,870 future cancers.14 It is suggested that a third of pediatric CT scans are unnecessary and that eliminating them could potentially reduce the number of CTattributable cancers by a third.15 In summary, our review of 36 patients with pulmonary nodules shows no obvious growth or enlargement of the nodules over the study period, suggesting low risk of malignancy. Routine follow-up CT tomography using ACCP/Fleischner Society guidelines may not apply in children without known malignancy. In low risk children with sub-centimetric nodules (4 mm in size on the initial computer tomography did not return for followup imaging. Larger studies which include different geographic locations are needed to verify our findings.
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Pediatric Pulmonology
