Introduction
Background
Pulmonary hamartomas, the most common benign tumors of the lung, are the third most common cause of solitary pulmonary nodules.
Accounting for 75% of all benign lung tumors, hamartomas are composed of tissues that are normally present in the lung, including fat, epithelial tissue, fibrous tissue, and cartilage. However, they exhibit disorganized growth.
Pulmonary hamartomas have little or no malignant potential, and most of them are asymptomatic, but because bronchogenic carcinoma is an important differential diagnosis,1 accurate imaging interpretation and diagnosis are important.2 Peripheral tumors are usually simply observed after the definitive diagnosis; central tumors may be excised. The prognosis is excellent.3,4,5,6
For excellent patient education resources, visit eMedicine's Procedures Center. Also, see eMedicine's patient education article Bronchoscopy.
See also the following related topics in Medscape:
Resource Center Lung Cancer
Specialty Site Radiology
Radiology CME and News
See also the following related topics in eMedicine:
Benign Lung Tumors
Congenital Lung Malformations
Pathophysiology
The exact etiology of pulmonary hamartomas is unknown, although several theories have been postulated, including that these hamartomas result from congenital malformation of a displaced bronchial anlage, hyperplasia of normal lung tissues, a cartilaginous benign neoplasm, or a response to inflammation. The lesions originate in the submucosal fibrous connective tissue of the bronchial wall, and they are composed of cartilaginous nests surrounded by connective tissue and mature fat cells. Fat is a key component, being present histologically in 54% of lesions in amalgamated series.
Myxomatous connective tissue, smooth muscle, bone, blood vessels, and other mesenchymal elements also may be seen histologically. The tissues are arranged in a disorganized manner. Malignant transformation is either extremely rare or nonexistent. Sarcomas arising in the wall of cystic mesenchymal hamartomas have been reported in children. However, cystic mesenchymal hamartomas are histologically different from adult pulmonary hamartomas.
Unlike carcinoid tumors, more than 90% of hamartomas are peripheral. Only 10% or less are located centrally, and even these are thought to arise pathologically in the connective tissue of small bronchi. On gross examination of pathology specimens, hamartomas seem to be well circumscribed and to usually be slightly lobulated. They may compress the adjacent lung. The peripheral location of pulmonary hamartomas usually renders them asymptomatic.
Pulmonary hamartomas grow slowly, and most of them are smaller than 4 cm, although they may reach 10 cm in diameter.7 The tumors are usually solitary, although multiple tumors in the Carney triad have been reported.8 The triad includes pulmonary chondroma, gastric epithelioid leiomyosarcoma (leiomyoblastoma), and functioning, extra-adrenal paraganglioma.9,10,11,12 A partial Carney triad may be seen when pulmonary hamartomas coexist with smooth muscle tumors of the stomach.13
Associations with other developmental anomalies and with benign, gastrointestinal stromal tumors, such as gastrointestinal autonomic nerve tumors,14 also have been reported. The Carney triad is usually seen in young women who present with slow-growing lung tumors. Multiple tumors in this setting often represent metastases, occasionally leiomyosarcomas of the stomach, which are a recognized complication.
Related eMedicine topic:
Carney Complex
Frequency
United States
Hamartomas represent 6-8% of all solitary pulmonary nodules and 0.25% in autopsy series. In rare cases, they are multiple.
International
The international frequency of pulmonary hamartoma may differ from that in the US.
Mortality/Morbidity
Pulmonary hamartomas are not associated per se with any significant morbidity or mortality. Problems may arise, however, when a pulmonary nodule is found in a person who smokes and when the nodule has atypical features. In this context, morbidity and mortality may be related to diagnostic procedures, such as bronchoscopy, percutaneous or endobronchial biopsy, or thoracotomy.15
Race
No race predilection exists for pulmonary hamartoma.
Sex
Hamartomas occur more often in men than in women, with a male-to-female ratio of between 2:1 and 3:1.
Age
The incidence of pulmonary hamartoma peaks in persons aged 50-60 years, but the average patient age at presentation is 45-50 years. Only 6% of these hamartomas are found in persons younger than 30 years. The tumors rarely occur in children.
Presentation
Pulmonary hamartomas are usually asymptomatic and are typically discovered as an incidental coin lesion on a routine chest radiograph. Occasionally, the tumors may be endobronchial, but they rarely cause hemoptysis or bronchial obstruction with signs and symptoms of coughing, wheezing, expectoration, leukocytosis, and fever.16,17 The Carney triad may exceptionally present, with malignant hypertension resulting from hormonally active extra-adrenal paragangliomas.10 Pheochromocytomas also have been reported with the Carney variant.18
Preferred Examination
Most pulmonary hamartomas are discovered incidentally on routine chest radiographs. Chest radiographic findings are rarely diagnostic, and most patients require a computed tomography (CT) scan examination for further evaluation and characterization of the lesion. In some cases, bronchoscopic or percutaneous biopsy may be necessary for a definitive diagnosis. Ultrasonography, magnetic resonance imaging (MRI), and radionuclide studies are useful techniques for investigating the Carney triad.
Limitations of Techniques
Chest radiography has limited value when calcification or fat cannot be detected in the lesion or when multiple nodules are present. CT scanning is expensive in terms of cost and radiation burden. CT scanning also has limitations in that characteristic calcification and/or fat in the lesion is absent in one third of patients. On CT scans, central endobronchial hamartomas may have features that are indistinguishable from those of a bronchial carcinoid.
See also the following related topics in Medscape:
CME CT Screening for Lung Cancer May Not Reduce Mortality
CME New Guidelines Issued on Lung Cancer Diagnosis and Management
CME PET Imaging Gaining Popularity as Diagnostic Tool in Lung Cancer
Differential Diagnoses
Lung Cancer, Non-Small Cell
Lung Cancer, Small Cell
Lung, Arteriovenous Malformation
Lung, Carcinoid
Lung, Metastases
Other Problems to Be Considered
- Bronchogenic carcinoma - Calcification rare
- Carcinoid tumor - May become heavily calcified
- Lymphoma - Does not usually become calcified
- Granuloma -Tuberculosis, histoplasmosis, coccidioidomycosis
- Arteriovenous malformation
- Rheumatoid nodule - Does not usually become calcified
- Pulmonary plasmacytoma - Does not usually become calcified
- Amyloidoma - Occasional peripheral calcification
- Solitary pulmonary metastasis - May become calcified or ossified if from osteosarcoma; chondrosarcoma; synovial sarcoma; giant cell tumor of the bone; or carcinoma of the colon, ovary, breast, or thyroid
- Treated metastatic choriocarcinoma
- Primary pulmonary osteosarcoma
- Pulmonary leiomyoma, fibroma, lipoma
- Myoblastoma
- Neurogenic tumors
- Endometriosis
- Papilloma
- Lipoid pneumonia
More on Hamartoma, Lung |
 Overview: Hamartoma, Lung |
| Imaging: Hamartoma, Lung |
| Follow-up: Hamartoma, Lung |
| Multimedia: Hamartoma, Lung |
| References |
| Next Page » |
References
Jacob S, Mohapatra D, Verghese M. Massive chondroid hamartoma of the lung clinically masquerading as bronchogenic carcinoma. Indian J Pathol Microbiol. Jan-Mar 2008;51(1):61-2. [Medline].
Hayward RH, Carabasi RJ. Malignant hamartoma of the lung: fact or fiction?. J Thorac Cardiovasc Surg. Apr 1967;53(4):457-66. [Medline].
Zakharov V, Schinstine M. Hamartoma of the lung. Diagn Cytopathol. May 2008;36(5):331-2. [Medline].
Jin MS, Ha HJ, Baek HJ, Lee JC, Koh JS. Adenomyomatous hamartoma of lung mimicking benign mucinous tumor in fine needle aspiration biopsy: a case report. Acta Cytol. May-Jun 2008;52(3):357-60. [Medline].
Wood B, Swarbrick N, Frost F. Diagnosis of pulmonary hamartoma by fine needle biopsy. Acta Cytol. Jul-Aug 2008;52(4):412-7. [Medline].
Guo W, Zhao YP, Jiang YG, Wang RW, Ma Z. Surgical treatment and outcome of pulmonary hamartoma: a retrospective study of 20-year experience. J Exp Clin Cancer Res. May 31 2008;27:8. [Medline].
Hutter J, Reich-Weinberger S, Hutarew G, et al. Giant pulmonary hamartoma--a rare presentation of a common tumor. Ann Thorac Surg. Aug 2006;82(2):e5-7. [Medline].
Kiryu T, Kawaguchi S, Matsui E, et al. Multiple chondromatous hamartomas of the lung: a case report and review of the literature with special reference to Carney syndrome. Cancer. Jun 15 1999;85(12):2557-61. [Medline]. [Full Text].
Lancha C, Diez L, Mitjavila M, et al. A case of complete Carney''s syndrome. Clin Nucl Med. Nov 1994;19(11):1008-10. [Medline].
Valverde K, Henderson M, Smith CR. Typical and atypical Carney''s triad presenting with malignant hypertension and papilledema. J Pediatr Hematol Oncol. Nov 2001;23(8):519-24. [Medline].
Wales PW, Drab SA, Kim PC. An unusual case of complete Carney''s triad in a 14-year-old boy. J Pediatr Surg. Aug 2002;37(8):1228-31. [Medline].
Rodriguez FJ, Aubry MC, Tazelaar HD, et al. Pulmonary chondroma: a tumor associated with Carney triad and different from pulmonary hamartoma. Am J Surg Pathol. Dec 2007;31(12):1844-53. [Medline].
Carney JA, Stratakis CA. Familial paraganglioma and gastric stromal sarcoma: a new syndrome distinct from the Carney triad. Am J Med Genet. Mar 1 2002;108(2):132-9. [Medline].
Lam KY, Law SY, Chu KM. Gastrointestinal autonomic nerve tumor of the esophagus. A clinicopathologic, immunohistochemical, ultrastructural study of a case and review of the literature. Cancer. Oct 15 1996;78(8):1651-9. [Medline].
Pittet O, Christodoulou M, Pezzetta E, et al. Video-assisted thoracoscopic resection of a small pulmonary nodule after computed tomography-guided localization with a hook-wire system. Experience in 45 consecutive patients. World J Surg. Mar 2007;31(3):575-8. [Medline].
Cosio BG, Villena V, Echave-Sustaeta J. Endobronchial hamartoma. Chest. Jul 2002;122(1):202-5. [Medline]. [Full Text].
Tomos P, Karaiskos T, Lahanas E, et al. Transverse bronchoplasty of the membranous wall after resection of an endobronchial hamartoma. Ann Thorac Surg. Feb 2007;83(2):703-4. [Medline].
Wahid ST, Jones R, Chawla SL. A new variant of Carney''s triad: phaeochromocytoma and chondrosarcoma. Postgrad Med J. Aug 2001;77(910):527-8. [Medline].
Seemann MD, Beinert T, Dienemann H. Identification of characteristics for malignancy of solitary pulmonary nodules using high-resolution computed tomography. Eur J Med Res. May 24 1996;1(8):371-6. [Medline].
Shady K, Siegel MJ, Glazer HS. CT of focal pulmonary masses in childhood. Radiographics. May 1992;12(3):505-14. [Medline]. [Full Text].
d''Alessandro MP, Kozakewich HP, Cooke KR. Radiologic-pathologic conference of Children''s Hospital Boston: new pulmonary nodules in a child undergoing treatment for a solid malignancy. Pediatr Radiol. 1996;26(1):19-21. [Medline].
Bennett LL, Lesar MS, Tellis CJ. Multiple calcified chondrohamartomas of the lung: CT appearance. J Comput Assist Tomogr. Jan-Feb 1985;9(1):180-2. [Medline].
Saqi A, Shaham D, Scognamiglio T, et al. Incidence and cytological features of pulmonary hamartomas indeterminate on CT scan. Cytopathology. Mar 27 2007;[Medline].
Erb RE, Delbeke D, Falke TH. Magnetic resonance imaging of Carney''s triad. South Med J. Sep 1994;87(9):951-5. [Medline].
Seo JB, Im JG, Goo JM. Atypical pulmonary metastases: spectrum of radiologic findings. Radiographics. Mar-Apr 2001;21(2):403-17. [Medline]. [Full Text].
Ramzy I. Pulmonary hamartomas: cytologic appearances of fine needle aspiration biopsy. Acta Cytol. Jan-Feb 1976;20(1):15-9. [Medline].
Konofaos P, Tomos P, Malagari K, et al. The role of ThinPrep cytology in the investigation of lung tumors. Surg Oncol. Nov 2006;15(3):173-8. [Medline].
Further Reading
Keywords
lung hamartoma, hamartochondroma, chondromatous hamartoma, Carney's triad, Carney triad, Carney's syndrome, Carney syndrome, pulmonary chondroma, solitary pulmonary nodule, benign lung tumor
