What are the other Names for this Condition? (Also known as/Symptoms)

• PIT (Primary Intrapulmonary Thymoma)
• Primary Intrapulmonary Thymoma (PIT)
• Thymoma of Lung

What is Intrapulmonary Thymoma? (Definition/Background Information)

• Intrapulmonary Thymoma is an epithelial lung tumor that is very similar to thymomas arising from the mediastinum. The origin of these tumors is believed to be from abnormally-placed tissues of the thymus (thymic rests)
• Intrapulmonary Thymoma is seen in a wide age range of individuals. The cause of formation of the tumor is unknown and the risk factors are not well-established
• The tumor is often present as a solitary mass in the hilar region or lung periphery. It may present obstructive signs and symptoms including cough and breathlessness
• The treatment of Intrapulmonary Thymoma involves surgery, which can be curative. However, regular follow-up is advised following a surgical removal of the tumor
• In a majority of cases, the prognosis of Primary Intrapulmonary Thymoma is very good with early appropriate treatment (complete removal of the tumor from the lung). However, the prognosis may be adversely affected by severe symptoms and associated paraneoplastic syndrome

Who gets Intrapulmonary Thymoma? (Age and Sex Distribution)

• Intrapulmonary Thymoma is generally observed in middle-aged adults (average age of 50 years); the age range of presentation is between 14 to 77 years
• Both males and females are affected, though some studies show a preference for females
• No specific racial or ethnic group predilection is noted

What are the Risk Factors for Intrapulmonary Thymoma? (Predisposing Factors)

• Currently, no definite risk factors have been identified for Intrapulmonary Thymoma

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Intrapulmonary Thymoma? (Etiology)

The cause of development of Intrapulmonary Thymoma is generally unknown. Research studies indicate that this tumor may have its origin from the thymic tissues that are abnormally-located in the lung region.

What are the Signs and Symptoms of Intrapulmonary Thymoma?

The signs and symptoms of Intrapulmonary Thymoma may include the following:

• Presence of a circumscribed mass in the airways (or bronchus) or peripheral lung region
• The tumors range in size from 5 mm to 12 cm and are typically single
• In rare cases, more than one tumor has been observed (multifocal tumor presentation)
• The growth of the tumor mass may obstruct the airway and occasionally are known to invade into the pleura
• Involvement of the lymph node is not generally associated with Intrapulmonary Thymoma (unlike seen in some mediastinal tumors)
• Tumors can cause obstructive symptoms including chest pain, cough, breathing difficulties, and blood in sputum
• Associated weight loss, fatigue, and fever may be present

Paraneoplastic syndrome associated symptoms - these are a set of signs and symptoms that occur in the body due to the presence of cancer, due to changes in the immune system. Due to this, the following conditions may be noted:

• Myasthenia gravis
• Good’s syndrome with hypogammaglobulinemia

Some small-sized tumors may remain asymptomatic and present no symptoms.

How is Intrapulmonary Thymoma Diagnosed?

There are a variety of tests the healthcare provider may employ to diagnose Primary Intrapulmonary Thymoma, which may include:

• Physical examination and complete medical history screening: During the physical exam, the healthcare provider may listen to the lung  with a stethoscope, to detect the presence of any abnormal lung sounds
• Imaging studies that may include a chest X-ray, MRI or CT scan of the lungs
• Arterial blood gases
• Lung function test
• Sputum cytology: This procedure involves the collection of mucus (sputum), coughed-up by the patient, which is then examined in a laboratory by a pathologist

A tissue biopsy refers to a medical procedure that involves the removal of cells or tissues, which are then examined by a pathologist. This can help establish a definitive diagnosis. The different biopsy procedures may include:

• Bronchoscopy: During bronchoscopy, a special medical instrument called a bronchoscope is inserted through the nose and into the lungs to collect small tissue samples. These samples are then examined by a pathologist, after the tissues are processed, in an anatomic pathology laboratory
• Thoracoscopy: During thoracoscopy, a surgical scalpel is used to make very tiny incisions into the chest wall. A medical instrument called a thoracoscope is then inserted into the chest, in order to examine and remove tissue from the chest wall, which are then examined further
• Thoracotomy: Thoracotomy is a surgical invasive procedure with special medical instruments to open-up the chest. This allows a physician to remove tissue from the chest wall or the surrounding lymph nodes of the lungs. A pathologist will then examine these samples under a microscope after processing the tissue in a laboratory
• Fine needle aspiration biopsy (FNAB): During fine needle aspiration biopsy, a device called a cannula is used to extract tissue or fluid from the lungs, or surrounding lymph nodes. These are then examined in an anatomic pathology laboratory, in order to determine any signs of abnormality. Nevertheless, FNAB is not a preferred method for the biopsy of lung tumors
• Autofluorescence bronchoscopy: It is a bronchoscopic procedure in which a bronchoscope is inserted through the nose and into the lungs and measure light from abnormal precancerous tissue. Samples are collected for further examination by a pathologist

Tissue biopsy from the affected lung:

• A biopsy of the tumor is performed and sent to a laboratory for a pathological examination. A pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. Examination of the biopsy under a microscope by a pathologist is considered to be gold standard in arriving at a conclusive diagnosis
• Biopsy specimens are studied initially using Hematoxylin and Eosin staining. The pathologist then decides on additional studies depending on the clinical situation
• Sometimes, the pathologist may perform special studies, which may include immunohistochemical stains, molecular testing, flow cytometric analysis and very rarely, electron microscopic studies, to assist in the diagnosis

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Intrapulmonary Thymoma?

The complications of Intrapulmonary Thymoma may include the following:

• Severe obstruction of the airways in case of a large-sized tumor
• Severe respiratory failure
• Metastasis of the tumor to other regions of the body can occur
• Recurrence of the tumor following its surgical removal; the recurrence may be observed in the lung or pleura

There may be complications related to the methods used in treating the condition and may include:

• Side effects of radiation therapy that may include sunburn-like rashes, where radiation was targeted, red or dry skin, heaviness of the breasts, and general fatigue
• Side effects of chemotherapy, which may include nausea, vomiting, hair loss, decreased appetite, mouth sores, fatigue, low blood cell counts, and a higher chance of developing infections
• The treatment can also cause infertility in men and women. Hence, measures to protect the individual’s fertility must be considered, before starting chemotherapy

How is Intrapulmonary Thymoma Treated?

The treatment of Intrapulmonary Thymoma may involve the following:

• The treatment of choice is a complete surgical excision. In a majority of cases, this can result in a cure, if the tumor is confined to the lung and can be completely removed
• Additionally, chemotherapy and/or radiation therapy may be necessary
• Breathing support may be necessary for some patients
• Follow-up care with regular screening and check-ups are important and encouraged

How can Intrapulmonary Thymoma be Prevented?

Currently, there are no known methods to prevent the development of Intrapulmonary Thymoma.

What is the Prognosis of Intrapulmonary Thymoma? (Outcomes/Resolutions)

• The prognosis of Intrapulmonary Thymoma is typically very good with early detection and appropriate treatment (complete surgical excision of the tumor); it can result in a disease-free state
• The most favorable factor for prognosis includes its surgical resectability, when the tumor is present only within the lung tissues (and not outside)
• Death is known to occur from severe signs and symptoms including associated paraneoplastic syndromes (such as myasthenia gravis causing respiratory failure)

Additional and Relevant Useful Information for Intrapulmonary Thymoma:

• Lung cancer incidence is around 35 cases per 100,000 populations: The incidence of lung cancer in non-smokers is 1-2 cases per 20,000 populations per year; its incidence in smokers is 20-30 times higher than that of non-smokers
• Smoking is highly-associated with squamous cell carcinomas and small cell carcinomas; nevertheless, for all lung cancer forms, smoking is the single most important risk factor