Pulmonary Hamartoma

Lung mass. Diagnosis? • Xray of the Week

Figure 1. What is the lung mass?

Figure 2. Pulmonary hamartoma

Figures 2A and 2B: Axial CT chest demonstrating well-demarcated, solitary peripheral, and inhomogeneous pulmonary mass arising from right lower lung lobe (yellow arrows). Note the low attenuation fat in the mass which is diagnostic of hamartoma. Small calcifications are also present. Figure 2C: Sagittal CT chest demonstrates posteriorly located well-demarcated solitary peripheral pulmonary mass. The mass is above the intact diaphragm (red arrow). Figure 2D: Coronal CT chest and abdomen demonstrates solitary lung mass arising from the right lung superior to the diaphragm with evidence of calcification. The mass is above the intact diaphragm (red arrow).

Discussion:

A hamartoma is a noncancerous focal proliferation of cells that is typically found in the organ or surrounding structures from which it arises (1). Hamartomas are commonly composed of mesenchymal tissue such as adipose tissue, epithelium, fibrous tissue, and cartilaginous tissue (2,3). Pulmonary hamartomas, dominantly composed of cartilaginous and adipose tissue, are the most common benign lung neoplasm, accounting for approximately 6% of solitary pulmonary nodules (3). They are commonly incidental findings found in the fourth to sixth decades of life with a male predilection and no current identifiable risk factors (3,9). Though often incidentally diagnosed as most patients are asymptomatic, symptoms can present depending on the location of the hamartoma (5). If located within the endobronchial structures, patients can present with cough, hemoptysis, or endobronchial obstruction with associated fever and dyspnea (5). Pulmonary hamartomas are found on diagnostic imaging; however, some cases may require definitive diagnosis with cytological evaluation after biopsy. On imaging, computed tomography (CT) is more sensitive to detecting pulmonary hamartomas compared to chest radiographs (4). Findings on CT demonstrate solitary, well-defined, round or lobulated masses or lobules that are predominantly peripherally located in the lungs (3,4). The size of the mass or nodule can be variable, typically around 2 to 5 cm. However, pulmonary hamartomas can also be larger than 10 cm, as seen in Figure 1 and 2 (8). Approximately 60% of the masses or nodules contain adipose tissue and 30% contain popcorn-like calcifications (6,7). A well-circumscribed solitary pulmonary nodule which contains fat and remains stable in size is virtually pathognomonic of a pulmonary hamartoma (7). If asymptomatic, patients with pulmonary hamartomas do not require treatment. Surgical resection is reserved for rapidly proliferating or symptomatic masses for which malignancy cannot be ruled out (9). Prognosis is typically excellent as hamartomas are commonly slow growing with rare malignant transformation (9). ​​​​

References:

1. Batsakis JG. Pathology consultation. Nomenclature of developmental tumors. Ann Otol Rhinol Laryngol. 1984 Jan-Feb;93(1 Pt 1):98-9. doi: 10.1177/000348948409300122. PMID: 6703601

2. Leiter Herrán F, Restrepo CS, Alvarez Gómez DI, Suby-Long T, Ocazionez D, Vargas D. Hamartomas from head to toe: an imaging overview. Br J Radiol. 2017;90(1071):20160607. doi:10.1259/bjr.20160607

3. Singh H, Khanna SK, Chandran V, Jetley RK. PULMONARY HAMARTOMA. Med J Armed Forces India. 1999;55(1):79-80. doi:10.1016/S0377-1237(17)30328-3

4. Radosavljevic V, Gardijan V, Brajkovic M, Andric Z. Lung hamartoma--diagnosis and treatment. Med Arch. 2012;66(4):281-2. doi: 10.5455/medarh.2012.66.281-282. PMID: 22919888

5. Thomas JW, Staerkel GA, Whitman GJ. Pulmonary hamartoma. AJR Am J Roentgenol. 1999 Jun;172(6):1643. doi: 10.2214/ajr.172.6.10350308. PMID: 10350308

6. Chai JL, Patz EF. CT of the lung: patterns of calcification and other high-attenuation abnormalities. AJR Am J Roentgenol. 1994;162 (5): 1063-6 doi:10.2214/ajr.162.5.8165982

7. Klein JS, Braff S. Imaging evaluation of the solitary pulmonary nodule. Clin. Chest Med. 2008;29 (1): 15-38, v. doi:10.1016/j.ccm.2007.11.007

8. Siegelman SS, Khouri NF, Scott WW Jr, Leo FP, Hamper UM, Fishman EK, Zerhouni EA. Pulmonary hamartoma: CT findings. Radiology. 1986 Aug;160(2):313-7. doi: 10.1148/radiology.160.2.3726106. PMID: 3726106

9. Lundeen KS, Raj MS, Rajasurya V, et al. Pulmonary Hamartoma. [Updated 2020 Jul 10]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan. https://www.ncbi.nlm.nih.gov/books/NBK539806/

Rabab Zaidi is an aspiring radiologist and fourth year medical student at the Loyola University Chicago Stritch School of Medicine (SSOM). She currently serves as the Community Support Co-Lead for the Loyola University COVID-19 Response Team and Co-President of the Radiology Interest Group at SSOM. At the Stritch School of Medicine, she has also worked with the Department of Radiation Oncology to study prostate cancer imaging and adaptive radiotherapy techniques, where she learned about the intersection of patient care and radiology. Rabab graduated magna cum laude with a degree in Economics from Loyola University Chicago in 2016. She is further passionate about mentorship, advocacy, and photography.

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Kevin M. Rice, MD is the president of Global Radiology CME

Dr. Rice is a radiologist with Renaissance Imaging Medical Associates and is currently the Vice Chief of Staff at Valley Presbyterian Hospital in Los Angeles, California. Dr. Rice has made several media appearances as part of his ongoing commitment to public education. Dr. Rice's passion for state of the art radiology and teaching includes acting as a guest lecturer at UCLA. In 2015, Dr. Rice and Natalie Rice founded Global Radiology CME to provide innovative radiology education at exciting international destinations, with the world's foremost authorities in their field. In 2016, Dr. Rice was nominated and became a semifinalist for a "Minnie" Award for the Most Effective Radiology Educator.

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