Discussion
Diagnosis With Brief Discussion
- Diagnosis
- Typical pulmonary carcinoid tumor
- Radiologic Findings
- Chest PA and lateral show an about 2.5 cm sized well-defined nodule in right middle lung field (Fig 1). On chest CT, the well-defined solitary nodule abutting the heart shows intense, homogenous enhancement after contrast administration without satellite nodules or enlargement of mediastinal LN (Fig 2). On PET-CT, the nodule shows high FDG uptake (max. SUV: 40) without any other lesions showing significantly increased uptake (Fig 3).
To exclude malignancy, right middle lobectomy was performed, and as the final histopathological diagnosis was ‘typical pulmonary carcinoid’. The patient showed no recurrence during 2 years of follow-up.
- Brief Review
- Pulmonary carcinoid tumors are low-grade malignant neoplasms showing indolent clinical course. It is thought to arise primarily within the central airways in 85% of cases and can manifest as hemoptysis or lobar obstruction. About 20% occur in a peripheral location and present as solitary pulmonary nodules, usually as a well-defined and homogeneous nodule.
Pulmonary carcinoid tumors are classified into one of two categories on the basis of cytologic criteria: atypical or typical. Typical carcinoids represent 80-90% of pulmonary carcinoids, and atypical carcinoids possess more malignant potential than typical ones. Some studies suggest that a higher percentage of patients with atypical pulmonary carcinoid tumors is related to smoking.
It is known that pulmonary carcinoid tumors usually demonstrate marked homogeneous enhancement on enhanced CT. However, some carcinoids may show heterogeneous enhancement or no enhancement. Internal calcification can be seen, but cavitation is rare. In cases of pulmonary carcinoids presenting as a solitary pulmonary nodule with intense enhancement, pulmonary sclerosing pneumocytoma (sclerosing hemangioma), intrapulmonary Castleman’s disease, metastasis, or primary lung cancer can be considered in the differential diagnosis.
It has long been suggested that carcinoid tumors show low FDG uptake on PET-CT. However, some newer studies have shown variable values of max. SUV,some values as high as 6 or greater.
- References
- 1. Meisinger QC, Klein JS, Butnor KJ, Gentchos G, Leavitt BJ. CT features of Peripheral Pulmonary Carcinoid Tumors. AJR 2011; 197:1073-1080.
2. Chong S, Lee KS, Chung MJ et al. Neuroendocrine Tumors of the Lung: Clinical, Pathologic, and Imaging Findings. RadioGraphics 2006;26(1):41-57.
3. Rekhtman N. Neuroendocrine Tumors of the Lung: An Update. Arch Pathol Lab Med. 2010. 134(11):1628-1638.
4. Moore W, Freiberg E, Bishawi M, Halbreiner MS, Matthews R, Baram D, Bilfinger TV. FDG-PET Imaging in patients with Pulmonary Carcinoid Tumor. Clin Nucl Med 2013; 38(7):501-505.
5. Kwon S, Lee KS, Song I, Kim TS. Thoracic Castleman disease: Computed Tomography and Clinical Findings. J Comput Assist Tomogr. 2013; 37:1-8.
6. Chung MJ, Lee KS, Han J, Sung YM, Chong S, Kwon OJ. Pulmonary Sclerosing Hemangioma Presenting as Solitary Pulmonary Nodule: Dynamic CT Findings and Histopathologic Comparisons. AJR 2006; 187:430-437.
7. Shin SY, Kim MY, Oh SY, Lee HJ, Hong SA, Jang SJ, Kim SS. Pulmonary Sclerosing Pneumocytoma of the Lung: CT Characteristics in a Large Series of a Tertiary Referral Center. Medicine 2015 Jan; 94(4):e498.
- Keywords
- Lung, Benign tumor,