Sarcomatoid carcinoma of the lung
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Associate Editor(s)-in-Chief: Maria Fernanda Villarreal, M.D. [2]
Synonyms and keywords: Primary sarcoma of the lung; Lung sarcoma; Sarcomatoid tumor of the lung
Overview
Sarcomatoid carcinoma of the lung is a rare histologic subtype of non-small cell lung cancer. Sarcomatoid carcinoma of the lung is a "sarcoma-like" carcinoma neoplasm. The overall prevalence of sarcomatoid carcinoma of the lung is 0.1% to 0.4% of all lung malignancies.[1] The pathogenesis of sarcomatoid carcinoma of the lung is characterized by a rare epithelial origin, and morphologic features suggestive of a malignant mesenchymal tumor.[1] The EGFR gene and K-ras mutations have been associated with the development of sarcomatoid carcinoma of the lung. The prevalence of sarcomatoid carcinoma of the lung is approximately 0.4 cases per 100,000 individuals worldwide. Common risk factors in the development of sarcomatoid carcinoma of the lung are smoking, family history of lung cancer, high levels of air pollution, radiation therapy to the chest, radon gas, asbestos, occupational exposure to chemical carcinogens, and previous lung diseases.[2] If left untreated, the majority of patients with sarcomatoid carcinoma of the lung may progress to develop lymphatic invasion and distant metastasis. Common complications of sarcomatoid carcinoma of the lung include respiratory failure, pneumonia, and distant metastasis. Prognosis is generally poor, and the average 5-survival rate of patients with sarcomatoid carcinoma of the lung is approximately 6%.[3]
Historical Perspective
- In 1987, EGFR gene mutations were first identified in the pathogenesis of sarcomatoid carcinoma of the lung.[4]
Classification
- Sarcomatoid carcinoma of the lung may be classified according to WHO classification into 5 subtypes:[5]
- Pleomorphic carcinoma
- Spindle cell carcinoma
- Giant cell carcinoma
- Carcinosarcoma
- Pulmonary blastoma
Pathophysiology
- The pathogenesis of sarcomatoid carcinoma of the lung is characterized by a rare epithelial origin and morphologic features suggestive of a malignant mesenchymal tumor.[1]
- Sarcomatoid carcinoma of the lung arises from epithelial cells but has morphologic features suggestive of a malignant mesenchymal tumor.
- The molecular pathogenesis of sarcomatoid carcinoma of the lung is characterized by the overexpression of the EGFR protein.
- The EGFR and K-ras gene mutations have been associated with the development of sarcomatoid carcinoma of the lung.
- On gross pathology, a large sized mass lesion, with upper lobe and peripheral location are characteristic findings of sarcomatoid carcinoma of the lung.
- On microscopic histopathological analysis, sarcomatous components are characteristic findings of sarcomatoid carcinoma of the lung.
Causes
- Sarcomatoid carcinoma of the lung may be caused by a mutation in the EGFR and K-ras genes.[1]
Differentiating sarcomatoid carcinoma of the lung from other Diseases
- Sarcomatoid carcinoma of the lung must be differentiated from other diseases that cause cough, weight loss, hemoptysis, and dyspnea among adults, such as:
- Tuberculosis
- Adenocarcinoma of the lung
- Pulmonary fungal disease
- Lung abscess
Epidemiology and Demographics
- The prevalence of sarcomatoid carcinoma of the lung is approximately 0.4 cases per 100,000 individuals worldwide.[1]
- The overall prevalence of sarcomatoid carcinoma of the lung is 0.1% to 0.4% of all lung malignancies.[1]
Age
- Sarcomatoid carcinoma of the lung is more commonly observed among patients aged 50 to 75 years old.
- Sarcomatoid carcinoma of the lung is more commonly observed among elderly patients and adults
Gender
- Males are more commonly affected with sarcomatoid carcinoma of the lung than females.
Race
- There is no racial predilection for sarcomatoid carcinoma of the lung.
Risk Factors
- Common risk factors in the development of sarcomatoid carcinoma of the lung are smoking, family history of lung cancer, high levels of air pollution, radiation therapy to the chest, radon gas, asbestos, occupational exposure to chemical carcinogens, and previous lung diseases.[6]
Natural History, Complications and Prognosis
- The majority of patients with sarcomatoid carcinoma of the lung remain are initially asymptomatic.
- Early clinical features include chronic cough, chest pain, and fatigue.
- If left untreated, the majority of patients with sarcomatoid carcinoma of the lung may progress to develop lymphatic invasion and distant metastasis.[7]
- Common complications of sarcomatoid carcinoma of the lung include respiratory failure, pneumonia, and distant metastasis.
- Prognosis is generally poor, the average 5-survival rate of patients with sarcomatoid carcinoma of the lung is approximately 6%.[3][7]
Diagnosis
Diagnostic Criteria
- The diagnosis of sarcomatoid carcinoma of the lung is made by lung biopsy.
- Biopsy findings associated with sarcomatoid carcinoma of the lung will depend on the subtype of tumor histology, common findings include:[7]
- Pleomorphic carcinoma subtype
- Spindle cell carcinoma subtype
- Giant cell carcinoma subtype
- Carcinosarcoma subtype
Symptoms
- Common symptoms of sarcomatoid carcinoma of the lung, may include:[7]
Physical Examination
- Patients with sarcomatoid carcinoma of the lung usually appear older in age in relation to their chronological age.[7]
- Physical examination may be remarkable for:
Inspection
- Hoarseness
- Rapid rate of breathing
Auscultation
- Present pleural friction rub
- Present egophony
- Crackling or bubbling noises
- Present whispered pectoriloquy
- Decreased/absent breath sounds
Percussion
- Hyporesonance
- Dull percussion
- Tactile fremitus
- Reduced chest expansion
Laboratory Findings
- There are no specific laboratory findings associated with sarcomatoid carcinoma of the lung.
Imaging Findings
- CT scan is the imaging modality of choice for sarcomatoid carcinoma of the lung.
- On CT, sarcomatoid carcinoma of the lung is characterized by the following findings:[7]
- Sarcomatoid carcinoma of the lung are typically peripherally located
- Usually measure apporximetely 4 cm in diameter
- Perihilar and mediastinal involvement
- Ground glass opacity
- Rapid growth
Other Diagnostic Studies
- Sarcomatoid carcinoma of the lung may also be diagnosed using bronchoscopy, mediastinoscopy, and transthoracic percutaneous fine needle aspiration.
Treatment
Medical Therapy
- The mainstay of therapy of sarcomatoid carcinoma of the lung is supportive care.
- Common medical treatment for sarcomatoid carcinoma of the lung is the platinum-based chemotherapy.[7]
Surgery
- Surgery is the mainstay of therapy for sarcomatoid carcinoma of the lung.
- Lobectomy along with regional lymph nodes (peribronchial and perihiliar lymph node dissection) in conjunction with pathological evaluation is the most common approach to the treatment of sarcomatoid carcinoma of the lung.
Prevention
- Effective measures for the primary prevention of sarcomatoid carcinoma of the lung include CT screening.[7]
- According to the U.S. Preventive Services Task Force (USPSTF), screening for lung cancer by low-dose computed tomography is recommended every year among smokers who are between 55 to 80 years old and who have history of smoke 30 pack-years or more and either continue to smoke or have quit within the past 15 years (grade B recommendation)
- Once diagnosed and successfully treated, patients with sarcomatoid carcinoma of the lung are followed-up every year. Follow-up testing includes CT screening.
References
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 Franks TJ, Galvin JR (2010). "Sarcomatoid carcinoma of the lung: histologic criteria and common lesions in the differential diagnosis". Arch. Pathol. Lab. Med. 134 (1): 49–54. doi:10.1043/2008-0547-RAR.1. PMID 20073605.
- ↑ Lung cancer. Canadian Cancer Society 2015. http://www.cancer.ca/en/cancer-information/cancer-type/lung/risks/?region=ab#Outdoor_air_pollution Accessed February 3, 2016
- ↑ 3.0 3.1 Yendamuri S, Caty L, Pine M, Adem S, Bogner P, Miller A, Demmy TL, Groman A, Reid M (2012). "Outcomes of sarcomatoid carcinoma of the lung: a Surveillance, Epidemiology, and End Results Database analysis". Surgery. 152 (3): 397–402. doi:10.1016/j.surg.2012.05.007. PMID 22739072.
- ↑ Timeline of lung cancer. http://cancerprogress.net/timeline/lung-cancer Accessed on February 17, 2016
- ↑ Sarcomatoid carcinoma of the lung. Wikipedia. https://en.wikipedia.org/wiki/Sarcomatoid_carcinoma_of_the_lung Accessed on March 31, 2016
- ↑ Lung cancer. Canadian Cancer Society 2015. http://www.cancer.ca/en/cancer-information/cancer-type/lung/risks/?region=ab#Outdoor_air_pollution Accessed February 3, 2016
- ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Hountis P, Moraitis S, Dedeilias P, Ikonomidis P, Douzinas M (2009). "Sarcomatoid lung carcinomas: a case series". Cases J. 2: 7900. doi:10.4076/1757-1626-2-7900. PMC 2740247. PMID 19830024.