Teoria del conocimiento

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EDUCATION EXHIBIT

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Tumors in the Tracheobronchial Tree: CT and FDG PET Features1
ONlINE-ONly CME
See www.rsna .org/education /rg_cme.html

Chang Min Park, MD • Jin Mo Goo, MD • Hyun Ju Lee, MD • Min AKim, MD • Chang Hyun Lee, MD • Mi-Jin Kang, MD A variety of tumors, including primary malignant tumors, secondary malignant tumors, and benign tumors, can occur in the tracheobronchial tree. Primary malignant tumors commonly originate from the surface epithelium or the salivary glands, whereas most benign tumors arise from the mesenchymal tissue. At computed tomography (CT), primary malignanttumors manifest as a polypoid lesion, a focal sessile lesion, eccentric narrowing of the airway lumen, or circumferential wall thickening. At fluorine 18 fluorodeoxyglucose (FDG) positron emission tomography (PET), most squamous cell carcinomas show high uptake, whereas adenoid cystic carcinoma and mucoepidermoid carcinoma show variable uptake depending on the grade of differentiation. High-grademalignancies tend to show high and homogeneous uptake. Carcinoid tumors commonly show intense enhancement at contrast material–enhanced CT, which can be helpful in making the diagnosis, and usually have lower uptake at FDG PET than would be expected for a malignant tumor. Secondary malignant tumors occur as a result of either hematogenous metastasis or direct invasion by a malignancy from an adjacentstructure. Their CT manifestations are similar to those of primary malignant tumors, with uptake at FDG PET depending primarily on the metabolic activity and degree of differentiation of the primary tumor. Among the benign tumors, hamartoma and lipoma can show characteristic CT findings such as “popcorn” calcification or internal fat. However, CT findings in most benign tumors are nonspecific. AtFDG PET, benign tumors usually show little or no uptake and can be differentiated from malignant tumors. Knowledge of the characteristic CT and FDG PET findings of tracheobronchial tumors can aid in diagnosis and treatment planning.
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lEARNING OBJECTIVES
After reading this article and taking the test, the reader will be able to:
■ List

and categorize the tumors that appear in thetracheobronchial tree. the clinical and pathologic features of these tracheobronchial tumors. the characteristic CT and FDG PET features of these tumors.

■ Describe

■ Discuss

TEACHING POINTS See last page

RSNA, 2009 • radiographics.rsnajnls.org

Abbreviations: ACC = adenoid cystic carcinoma, FDG = fluorine 18 fluorodeoxyglucose, H-E = hematoxylin-eosin, MEC = mucoepidermoid carcinoma, SCC =squamous cell carcinoma, SUV = standardized uptake value, 3D = three-dimensional RadioGraphics 2009; 29:55–71 • Published online 10.1148/rg.291085126 • Content Codes:
1 From the Department of Radiology, Seoul National University College of Medicine, and Institute of Radiation Medicine, Seoul National University Medical Research Center, 101 Daehangno, Jongno-gu, Seoul 110-744, Korea (C.M.P.,J.M.G., H.J.L., C.H.L., M.J.K.); Department of Pathology, Seoul National University College of Medicine, Seoul, Korea (M.A.K.); and Seoul National University Hospital, Gangnam Healthcare Center, Seoul, Korea (C.H.L.). Presented as an education exhibit at the 2007 RSNA Annual Meeting. Received May 7, 2008; revision requested May 31; final revision received July 21; accepted August 4. All authors haveno financial relationships to disclose. Address correspondence to J.M.G. (e-mail: jmgoo@plaza.snu.ac.kr).

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RSNA, 2009

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January-February 2009

radiographics.rsnajnls.org

Tumors in the tracheobronchial tree are rare, accounting for less than 0.4% of all body tumors (1). However, the vast majority of tracheobronchial tumors in adults are malignant, although various benign tumors...