Computed Tomography Correlation of Airway Disease With Bronchoscopy—Part II: Tracheal Neoplasms Lamia Jamjoom, MD,a Emmanuel C. Obusez, MD,b Jacobo Kirsch, MD,c Thomas Gildea, MD,d and Tan-Lucien Mohammed, MD, FCCPe
This pictorial essay illustrates, describes, and correlates computed tomographic findings of tracheal neoplasms with fiberoptic bronchoscopy findings. Corresponding computed tomography (CT) and bronchoscopy findings of common primary tracheal neoplasms; squamous cell papilloma, papillomatosis, squamous cell carcinoma, adenoid cystic adenoma, non-Hodgkin's lymphoma, and a secondary malignant neoplasm of the trachea; and renal cell carcinoma were correlated.
Education Goals Primary tracheal neoplasms comprise 2% of all respiratory tract tumors and are divided into benign and malignant neoplasms.1,2 Benign tumors arise from mesenchymal or epithelial tissue and are commonly found in children.1 In contrast, malignant neoplasms are mostly adult tumors and arise from surface epithelium, salivary glands, or mesenchymal structures.2 Secondary tracheal neoplasms are extremely rare; however, direct tracheal invasion and metastasis from breast cancer, renal carcinoma, and colorectal carcinoma is not uncommon. Bronchoscopy with biopsy is the gold standard for the diagnosis of tracheal neoplasms.3 This modality From the aDepartment of Radiology, King Abdul Aziz University Hospital, Jeddah, Saudi Arabia; bImaging Institute, Cleveland Clinic, Cleveland, OH; cDivision of Radiology, Cleveland Clinic Florida, Weston, FL; d Department of Pulmonary, Allergy and Critical Care, Cleveland Clinic, Cleveland, OH; and eDepartment of Radiology, Virginia Mason Medical Center, Seattle, WA. Reprint requests: Tan-Lucien H. Mohammed, MD, FCCP, Department of Radiology, Virginia Mason Medical Center, Seattle, WA. E-mail: [email protected]. Curr Probl Diagn Radiol 2014;43:278–284. & 2014 Mosby, Inc. All rights reserved. 0363-0188/$36.00 + 0 http://dx.doi.org/10.1067/j.cpradiol.2014.02.005
278
allows for direct visualization and evaluation of abnormal mucosal lesions in the lumen of the airway and therapeutic intervention or histopathologic analysis.3 However, determination of extent of disease dissemination or airway patency distal to the lesion is difficult. Computed tomography (CT), on the contrary, is an excellent modality for diagnosis, evaluationof the airway distal to the obstruction, extent of disease spread, and preprocedural planning.3 Notwithstanding, it fails to accurately determine tumor relationship with the submucosa or mucosa.3 Hence, conventional management of tracheal tumors with both CT and bronchoscopy is warranted. This pictorial essay illustrates, describes, and correlates CT findings of common benign and primary malignant tumors of the trachea with fiberoptic bronchoscopy.
Teaching Points and Pictorials Benign Neoplasms of the Trachea Squamous Cell Papilloma Squamous cell papilloma is a rare type of papillomatosis found in adults and manifests solely as solitary lesions.1 It is the most common benign central airway neoplasm. These tumors are 4 times more likely to be found in males than in females and usually present in the fifth to seventh decade of life. A strong association exists with cigarette smoking and transformation to invasive carcinoma. Like papillomatosis, these are associated with human papilloma virus, and tumors arise from the proliferation of squamous epithelium around a fibrovascular core. CT findings may reveal solitary lobulated or flat intraluminal masses without extraluminal extension or calcification4 (Fig 1A and B). Bronchoscopy reveals superficial
Curr Probl Diagn Radiol, September/October 2014
FIG 1. Tracheal papilloma or squamous cell papilloma. (A) Axial image of the anterolateral trachea with multiple papillary masses (white arrow). (B) Coronal image with multiple lobulated intramural massess with calcifications in the left trachea. (C and D) Bronchoscopy images showing multiple cauliflowerlike papillary masses in the tracheas (Black arrows). (Color version of figure is available online.)
sessile, papillomary masses or cauliflowerlike widebased tumor causing airway obstruction and narrowing5 (Fig 1C and D). Papillomatosis Papillomas are the most common recurrent benign tumors of the trachea and larynx and are commonly found in children. Its etiology is traced to human papilloma virus 6 and 11 via maternal vertical transmission during birth.1 It is also known as laryngotracheal papillomatosis or recurrent respiratory papillomatosis; these lesions are usually indolent and
Curr Probl Diagn Radiol, September/October 2014
primarily affect the trachea and larynx. Malignant transformation to squamous cell carcinoma occurs in 10% of cases.1 CT findings may show multiple, small, scattered mucosal nodules protruding into the tracheal lumen, or nodular airway wall thickening.6 Nodules may be sessile or pedunculated and may aggregate into enlarged air filled cysts of varying size with thick or thin walls. Nodules may also show central cavitations if there is dissemination into the lung parenchyma. Bronchoscopic findings reveal multiple sessile or pedunculated “cauliflowerlike” lesions scattered in the tracheal wall.7
279
FIG 2. Squamous cell carcinoma. (A-D) Axial images showing lumen of trachea and bronchi with polypoid circumferential wall thickening with irregular narrowing (white arrows). (E) Bronchoscopy showing diffusely infiltrating exophytic, ulcerating, scattered masses encompassing the trachea. (Color version of figure is available online.)
280
Curr Probl Diagn Radiol, September/October 2014
FIG 3. Adenoid cystic adenoma. (A) Large, lobular intraluminal, obstructing broad-based mass with its epicenter in the posterior tracheal wall (white arrow). (B and C) Bronchoscopy with a red, vascular, bulky intraluminal mass completely obstructing the trachea. (Color version of figure is available online.)
Primary Malignant Neoplasms of the Trachea Squamous Cell Carcinoma Squamous cell carcinoma is the most frequently occurring primary malignancy of the trachea.2 It arises from the tracheal epithelial tissue and is also commonly found in the main, lobar, and segmental bronchi.2 Tumor presentation is seen in the sixth and seventh decades of life with male predominance. There is a strong association with cigarette smoking and other respiratory tract malignancies, and tumor prognosis is poor with characteristically rapidly progressive growth and mediastinal or pulmonary metastasis at diagnosis.2 CT findings may reveal a large centrally located intraluminal, polypoid mass obstructing the tracheal lumen, or a focal, flat lesion with circumferential wall thickening. Other descriptive findings include a sessile mass with eccentric,
Curr Probl Diagn Radiol, September/October 2014
irregular narrowing of the subglottic tracheal lumen4 (Fig 2A-D). Bronchoscopic findings may reveal exophytic or ulcerative masses with lateral trachea wall involvement that may be localized, diffusely infiltrating, or with multiple areas of scattered lesions8 (Fig 2E). Adenoid Cystic Adenoma Adenoid cystic adenoma is an indolent, encapsulated, slow-growing salivary gland tumor found in the airway, lungs, breast, skin, and cervix.2 Previously known as cylindroma or adenocystic carcinoma, it is the most common salivary gland tumor of the trachea and second most common tracheal malignancy.9 It is equally prevalent in males and females with peak incidence of presentation in the fifth decade. These slow-growing tumors exert a mass effect on the adjacent mediastinal structures rather than directly invade them but may metastasize hematogenously.
281
FIG 4. Non-Hodgkin's lymphoma. (A and B) Axial images of lobulated soft tissue mass causing intraluminal narrowing of the trachea and bronchi (white arrows). Note the palliative stent in the esophagus due to the mass effect of the lymphoma mass. (C and D) Coronal images showing the lobulated mass invading the carina (white arrows). (E) Bronchoscopy showing collapse of trachea with an extraluminal mass extending into the distal trachea. (Color version of figure is available online.) 282
Curr Probl Diagn Radiol, September/October 2014
FIG 5. Renal cell carcinoma. (A and B) Axial images showing airway narrowing from mass effect with extension into lumen of lower trachea and bronchi with mediastinal lymphadenopathy (white arrows). (C and D) Bronchoscopy of the trachea and bronchi with airway narrowing and exophytic white plaques with submucosal infiltration (black arrows). (Color version of figure is available online.)
CT findings may reveal an intraluminal, polypoid or broad-based mass with extension through the posterolateral or anterolateral tracheal wall or a diffusely infiltrating smooth lesion, described as a lobulated or irregular contoured circumferential wall growth in the tracheobronchial mucosa causing luminal narrowing9 (Fig 3A). Bronchoscopy findings may reveal a bulky mass or circumferential lesion within the trachea. The tumor appearance may vary but is predominantly red, granular or rubbery, and easily friable (Fig 3B and C) Borders of the lesions may be well-defined or diffusely infiltrating. Margins of projecting masses may also show mucosal elevation or vascularization; evidence of infiltration beneath the mucosa.
Curr Probl Diagn Radiol, September/October 2014
Primary Tracheal Non-Hodgkin’s Lymphoma Non-Hodgkin's lymphoma (NHL) is a malignant lymphoid neoplasm usually located in lymph nodes, the abdomen, and mediastinum.10 Primary tracheal NHL accounts for 0.2%-3% of all tracheal tumors.11 It is thought to arise from mesenchymal B and T cells in the upper airway. Although tracheal and bronchial involvement is uncommon in patients with extranodal disease, primary extranodal neoplasms may arise from mucosa-associated lymphoid tissue of Waldeyer ring, trachea, bronchi, and gastrointestinal mucosa.10,11 CT findings may show an irregular, lobulated, or polypoid soft tissue mass with intraluminal narrowing of the trachea10 (Fig 4A-D). Bronchoscopy findings vary and may reveal circumferential stenosis, multiple friable or
283
polypoid submucosal nodules, or a subglottic mass resembling granulation tissue12 (Fig 4E and F).
Secondary Malignant Neoplasm of the Trachea Renal Clear Cell Carcinoma Tracheal or endobronchial metastases of primary cancers are extremely rare.13 These malignancies usually present as late manifestations of an asymptomatic primary tumor or diagnosed before primary tumor detection. Tracheal metastasis from nonpulmonary malignancies such as renal cell carcinoma is also rare; however, it has been reported.14 CT findings for renal cell carcinoma may reveal mediastinal lymphadenopathy in up to 50% of cases and single or multiple intraluminal polypoid masses emanating from the tracheal wall (Fig 5A-F).14 Airway narrowing due to mass obstruction is not an uncommon finding. Bronchoscopy tracheal findings may show exophytic, lobulated, fragile tumors with patchy white plaques and submucosal infiltration. These friable masses are highly vascular and easily bleed (Fig 5G and H).
REFERENCES 1. Wilson RW, Kirejczyk W. Pathological and radiological correlation of endobronchial neoplasms: Part I, benign tumors. Ann Diagn Pathol 1997;1:31-46. 2. Wilson RW, Frazier AA. Pathological-radiological correlations: Pathological and radiological correlation of endobronchial neoplasms: Part II, malignant tumors. Ann Diagn Pathol 1998;2:31-4. 3. Colice GL, Chappel GJ, Frenchman SM, et al. Comparison of computerized tomography with fiberoptic bronchoscopy in
284
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
identifying endobronchial abnormalities in patients with known or suspected lung cancer. Am Rev Respir Dis 1985;131:397-400. Rosado-de-Christenson ML, Templeton PA, Moran CA. Bronchogenic carcinoma: Radiologic-pathologic correlation. Radiographics 1994;14:429-46 [quiz 447-8]. Naka Y, Nakao K, Hamaji Y, et al. Solitary squamous cell papilloma of the trachea. Ann Thorac Surg 1993;55: 189-93. Pipavath SN, Manchanda V, Lewis DH, et al. 18F FDG-PET/ CT findings in recurrent respiratory papillomatosis. Ann Nucl Med 2008;22:433-6. Colt HG, Murgu SD, Jung B, et al. Multimodality bronchoscopic imaging of recurrent respiratory papillomatosis. Laryngoscope 2010;120:468-72. Velez Jo ET, Morehead RS. Hemoptysis and dyspnea in a 67-year-old man with a normal chest radiograph. Chest 1999; 116:803-7. Kwak SH, Lee KS, Chung MJ, et al. Adenoid cystic carcinoma of the airways: Helical CT and histopathologic correlation. Am J Roentgenol 2004;183:277-81. Gasparetto TD, Azevedo FB, Toledo A, et al. Primary tracheal non-Hodgkin lymphoma: Case report with an emphasis on computed tomography findings. J Thorac Imaging 2010;25: W24-6. Luick ML, Hansen EK, Greenberg MS, et al. Primary tracheal non-Hodgkin’s lymphoma. J Clin Oncol 2011;29: e193-5. Gill MT, Cotelingam JD, Lowery-Nordberg M, et al. Tracheal non-Hodgkin’s lymphoma masquerading as benign granulation tissue: A report of two cases. Ann Otol Rhinol Laryngol 2010;119:431-5. Kiryu T, Hoshi H, Matsui E, et al. Endotracheal/endobronchial metastases: Clinicopathologic study with special reference to developmental modes. Chest 2001;119:768-75. Shavit L, Maly B, Rosenbaum E, et al. Endotracheal metastases in renal cell carcinoma: A life-threatening but treatable complication. Eur J Intern Med 2007;18:161-3.
Curr Probl Diagn Radiol, September/October 2014
This pictorial essay illustrates, describes, and correlates computed tomographic findings of tracheal neoplasms with fiberoptic bronchoscopy findings. Corresponding computed tomography (CT) and bronchoscopy findings of common primary tracheal neoplasms; squamous cell papilloma, papillomatosis, squamous cell carcinoma, adenoid cystic adenoma, non-Hodgkin's lymphoma, and a secondary malignant neoplasm of the trachea; and renal cell carcinoma were correlated.
Education Goals Primary tracheal neoplasms comprise 2% of all respiratory tract tumors and are divided into benign and malignant neoplasms.1,2 Benign tumors arise from mesenchymal or epithelial tissue and are commonly found in children.1 In contrast, malignant neoplasms are mostly adult tumors and arise from surface epithelium, salivary glands, or mesenchymal structures.2 Secondary tracheal neoplasms are extremely rare; however, direct tracheal invasion and metastasis from breast cancer, renal carcinoma, and colorectal carcinoma is not uncommon. Bronchoscopy with biopsy is the gold standard for the diagnosis of tracheal neoplasms.3 This modality From the aDepartment of Radiology, King Abdul Aziz University Hospital, Jeddah, Saudi Arabia; bImaging Institute, Cleveland Clinic, Cleveland, OH; cDivision of Radiology, Cleveland Clinic Florida, Weston, FL; d Department of Pulmonary, Allergy and Critical Care, Cleveland Clinic, Cleveland, OH; and eDepartment of Radiology, Virginia Mason Medical Center, Seattle, WA. Reprint requests: Tan-Lucien H. Mohammed, MD, FCCP, Department of Radiology, Virginia Mason Medical Center, Seattle, WA. E-mail: [email protected]. Curr Probl Diagn Radiol 2014;43:278–284. & 2014 Mosby, Inc. All rights reserved. 0363-0188/$36.00 + 0 http://dx.doi.org/10.1067/j.cpradiol.2014.02.005
278
allows for direct visualization and evaluation of abnormal mucosal lesions in the lumen of the airway and therapeutic intervention or histopathologic analysis.3 However, determination of extent of disease dissemination or airway patency distal to the lesion is difficult. Computed tomography (CT), on the contrary, is an excellent modality for diagnosis, evaluationof the airway distal to the obstruction, extent of disease spread, and preprocedural planning.3 Notwithstanding, it fails to accurately determine tumor relationship with the submucosa or mucosa.3 Hence, conventional management of tracheal tumors with both CT and bronchoscopy is warranted. This pictorial essay illustrates, describes, and correlates CT findings of common benign and primary malignant tumors of the trachea with fiberoptic bronchoscopy.
Teaching Points and Pictorials Benign Neoplasms of the Trachea Squamous Cell Papilloma Squamous cell papilloma is a rare type of papillomatosis found in adults and manifests solely as solitary lesions.1 It is the most common benign central airway neoplasm. These tumors are 4 times more likely to be found in males than in females and usually present in the fifth to seventh decade of life. A strong association exists with cigarette smoking and transformation to invasive carcinoma. Like papillomatosis, these are associated with human papilloma virus, and tumors arise from the proliferation of squamous epithelium around a fibrovascular core. CT findings may reveal solitary lobulated or flat intraluminal masses without extraluminal extension or calcification4 (Fig 1A and B). Bronchoscopy reveals superficial
Curr Probl Diagn Radiol, September/October 2014
FIG 1. Tracheal papilloma or squamous cell papilloma. (A) Axial image of the anterolateral trachea with multiple papillary masses (white arrow). (B) Coronal image with multiple lobulated intramural massess with calcifications in the left trachea. (C and D) Bronchoscopy images showing multiple cauliflowerlike papillary masses in the tracheas (Black arrows). (Color version of figure is available online.)
sessile, papillomary masses or cauliflowerlike widebased tumor causing airway obstruction and narrowing5 (Fig 1C and D). Papillomatosis Papillomas are the most common recurrent benign tumors of the trachea and larynx and are commonly found in children. Its etiology is traced to human papilloma virus 6 and 11 via maternal vertical transmission during birth.1 It is also known as laryngotracheal papillomatosis or recurrent respiratory papillomatosis; these lesions are usually indolent and
Curr Probl Diagn Radiol, September/October 2014
primarily affect the trachea and larynx. Malignant transformation to squamous cell carcinoma occurs in 10% of cases.1 CT findings may show multiple, small, scattered mucosal nodules protruding into the tracheal lumen, or nodular airway wall thickening.6 Nodules may be sessile or pedunculated and may aggregate into enlarged air filled cysts of varying size with thick or thin walls. Nodules may also show central cavitations if there is dissemination into the lung parenchyma. Bronchoscopic findings reveal multiple sessile or pedunculated “cauliflowerlike” lesions scattered in the tracheal wall.7
279
FIG 2. Squamous cell carcinoma. (A-D) Axial images showing lumen of trachea and bronchi with polypoid circumferential wall thickening with irregular narrowing (white arrows). (E) Bronchoscopy showing diffusely infiltrating exophytic, ulcerating, scattered masses encompassing the trachea. (Color version of figure is available online.)
280
Curr Probl Diagn Radiol, September/October 2014
FIG 3. Adenoid cystic adenoma. (A) Large, lobular intraluminal, obstructing broad-based mass with its epicenter in the posterior tracheal wall (white arrow). (B and C) Bronchoscopy with a red, vascular, bulky intraluminal mass completely obstructing the trachea. (Color version of figure is available online.)
Primary Malignant Neoplasms of the Trachea Squamous Cell Carcinoma Squamous cell carcinoma is the most frequently occurring primary malignancy of the trachea.2 It arises from the tracheal epithelial tissue and is also commonly found in the main, lobar, and segmental bronchi.2 Tumor presentation is seen in the sixth and seventh decades of life with male predominance. There is a strong association with cigarette smoking and other respiratory tract malignancies, and tumor prognosis is poor with characteristically rapidly progressive growth and mediastinal or pulmonary metastasis at diagnosis.2 CT findings may reveal a large centrally located intraluminal, polypoid mass obstructing the tracheal lumen, or a focal, flat lesion with circumferential wall thickening. Other descriptive findings include a sessile mass with eccentric,
Curr Probl Diagn Radiol, September/October 2014
irregular narrowing of the subglottic tracheal lumen4 (Fig 2A-D). Bronchoscopic findings may reveal exophytic or ulcerative masses with lateral trachea wall involvement that may be localized, diffusely infiltrating, or with multiple areas of scattered lesions8 (Fig 2E). Adenoid Cystic Adenoma Adenoid cystic adenoma is an indolent, encapsulated, slow-growing salivary gland tumor found in the airway, lungs, breast, skin, and cervix.2 Previously known as cylindroma or adenocystic carcinoma, it is the most common salivary gland tumor of the trachea and second most common tracheal malignancy.9 It is equally prevalent in males and females with peak incidence of presentation in the fifth decade. These slow-growing tumors exert a mass effect on the adjacent mediastinal structures rather than directly invade them but may metastasize hematogenously.
281
FIG 4. Non-Hodgkin's lymphoma. (A and B) Axial images of lobulated soft tissue mass causing intraluminal narrowing of the trachea and bronchi (white arrows). Note the palliative stent in the esophagus due to the mass effect of the lymphoma mass. (C and D) Coronal images showing the lobulated mass invading the carina (white arrows). (E) Bronchoscopy showing collapse of trachea with an extraluminal mass extending into the distal trachea. (Color version of figure is available online.) 282
Curr Probl Diagn Radiol, September/October 2014
FIG 5. Renal cell carcinoma. (A and B) Axial images showing airway narrowing from mass effect with extension into lumen of lower trachea and bronchi with mediastinal lymphadenopathy (white arrows). (C and D) Bronchoscopy of the trachea and bronchi with airway narrowing and exophytic white plaques with submucosal infiltration (black arrows). (Color version of figure is available online.)
CT findings may reveal an intraluminal, polypoid or broad-based mass with extension through the posterolateral or anterolateral tracheal wall or a diffusely infiltrating smooth lesion, described as a lobulated or irregular contoured circumferential wall growth in the tracheobronchial mucosa causing luminal narrowing9 (Fig 3A). Bronchoscopy findings may reveal a bulky mass or circumferential lesion within the trachea. The tumor appearance may vary but is predominantly red, granular or rubbery, and easily friable (Fig 3B and C) Borders of the lesions may be well-defined or diffusely infiltrating. Margins of projecting masses may also show mucosal elevation or vascularization; evidence of infiltration beneath the mucosa.
Curr Probl Diagn Radiol, September/October 2014
Primary Tracheal Non-Hodgkin’s Lymphoma Non-Hodgkin's lymphoma (NHL) is a malignant lymphoid neoplasm usually located in lymph nodes, the abdomen, and mediastinum.10 Primary tracheal NHL accounts for 0.2%-3% of all tracheal tumors.11 It is thought to arise from mesenchymal B and T cells in the upper airway. Although tracheal and bronchial involvement is uncommon in patients with extranodal disease, primary extranodal neoplasms may arise from mucosa-associated lymphoid tissue of Waldeyer ring, trachea, bronchi, and gastrointestinal mucosa.10,11 CT findings may show an irregular, lobulated, or polypoid soft tissue mass with intraluminal narrowing of the trachea10 (Fig 4A-D). Bronchoscopy findings vary and may reveal circumferential stenosis, multiple friable or
283
polypoid submucosal nodules, or a subglottic mass resembling granulation tissue12 (Fig 4E and F).
Secondary Malignant Neoplasm of the Trachea Renal Clear Cell Carcinoma Tracheal or endobronchial metastases of primary cancers are extremely rare.13 These malignancies usually present as late manifestations of an asymptomatic primary tumor or diagnosed before primary tumor detection. Tracheal metastasis from nonpulmonary malignancies such as renal cell carcinoma is also rare; however, it has been reported.14 CT findings for renal cell carcinoma may reveal mediastinal lymphadenopathy in up to 50% of cases and single or multiple intraluminal polypoid masses emanating from the tracheal wall (Fig 5A-F).14 Airway narrowing due to mass obstruction is not an uncommon finding. Bronchoscopy tracheal findings may show exophytic, lobulated, fragile tumors with patchy white plaques and submucosal infiltration. These friable masses are highly vascular and easily bleed (Fig 5G and H).
REFERENCES 1. Wilson RW, Kirejczyk W. Pathological and radiological correlation of endobronchial neoplasms: Part I, benign tumors. Ann Diagn Pathol 1997;1:31-46. 2. Wilson RW, Frazier AA. Pathological-radiological correlations: Pathological and radiological correlation of endobronchial neoplasms: Part II, malignant tumors. Ann Diagn Pathol 1998;2:31-4. 3. Colice GL, Chappel GJ, Frenchman SM, et al. Comparison of computerized tomography with fiberoptic bronchoscopy in
284
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
identifying endobronchial abnormalities in patients with known or suspected lung cancer. Am Rev Respir Dis 1985;131:397-400. Rosado-de-Christenson ML, Templeton PA, Moran CA. Bronchogenic carcinoma: Radiologic-pathologic correlation. Radiographics 1994;14:429-46 [quiz 447-8]. Naka Y, Nakao K, Hamaji Y, et al. Solitary squamous cell papilloma of the trachea. Ann Thorac Surg 1993;55: 189-93. Pipavath SN, Manchanda V, Lewis DH, et al. 18F FDG-PET/ CT findings in recurrent respiratory papillomatosis. Ann Nucl Med 2008;22:433-6. Colt HG, Murgu SD, Jung B, et al. Multimodality bronchoscopic imaging of recurrent respiratory papillomatosis. Laryngoscope 2010;120:468-72. Velez Jo ET, Morehead RS. Hemoptysis and dyspnea in a 67-year-old man with a normal chest radiograph. Chest 1999; 116:803-7. Kwak SH, Lee KS, Chung MJ, et al. Adenoid cystic carcinoma of the airways: Helical CT and histopathologic correlation. Am J Roentgenol 2004;183:277-81. Gasparetto TD, Azevedo FB, Toledo A, et al. Primary tracheal non-Hodgkin lymphoma: Case report with an emphasis on computed tomography findings. J Thorac Imaging 2010;25: W24-6. Luick ML, Hansen EK, Greenberg MS, et al. Primary tracheal non-Hodgkin’s lymphoma. J Clin Oncol 2011;29: e193-5. Gill MT, Cotelingam JD, Lowery-Nordberg M, et al. Tracheal non-Hodgkin’s lymphoma masquerading as benign granulation tissue: A report of two cases. Ann Otol Rhinol Laryngol 2010;119:431-5. Kiryu T, Hoshi H, Matsui E, et al. Endotracheal/endobronchial metastases: Clinicopathologic study with special reference to developmental modes. Chest 2001;119:768-75. Shavit L, Maly B, Rosenbaum E, et al. Endotracheal metastases in renal cell carcinoma: A life-threatening but treatable complication. Eur J Intern Med 2007;18:161-3.
Curr Probl Diagn Radiol, September/October 2014
