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

• Primary Malignant Melanoma of Lung
• Primary Pulmonary Melanoma

What is Primary Melanoma of Lung? (Definition/Background Information)

• A melanoma is a type of cancer that develops from cells, called melanocytes. Melanocytes are cells that produce melanin; the pigment that gives skin its color
• Primary Melanoma of Lung is an extremely uncommon tumor affecting the lung airways. It is typically observed in both men and women in the 6th decade
• Since, secondary or metastatic melanoma tumors to the lungs are much more common, the diagnosis of a Primary Pulmonary Melanoma is through a process of exclusion. Evaluation for melanoma at other common sites, such as the skin, mucosa, or eyes, must be considered prior to diagnosing a Primary Melanoma of Lung
• The cause of formation of Primary Melanoma of Lung is unknown and presently the risk factors are not well-understood
• The tumor is often present as a solitary mass affecting the bronchus/airway. It usually presents obstructive signs and symptoms including chest pain, cough, and breathlessness. Spread of the melanoma to other organs, such as the liver and brain, is commonly noted
• The treatment of Primary Malignant Melanoma of Lung involves surgery, chemotherapy and/or radiation therapy. In a majority of cases, the prognosis is guarded or poor despite adequate treatment

Who gets Primary Melanoma of Lung? (Age and Sex Distribution)

• Primary Melanoma of Lung is an extremely rare tumor that is generally observed in adults
• The peak age of presentation is between 50-60 years; however, an age range of 29-80 years is noted
• Both males and females are affected, though some studies indicate a preference for males
• No specific racial or ethnic group predilection is noted

What are the Risk Factors for Primary Melanoma of Lung? (Predisposing Factors)

• Presently, no clearly defined risk factors for Primary Melanoma of Lung or any predisposing exposure have been established

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 Primary Melanoma of Lung? (Etiology)

The cause of development of Primary Melanoma of Lung is generally unknown.

• The tumor has not been associated with any known premalignant lesions
• In some cases, melanocytic nevus in the vicinity of the tumor has been described, although presently no benign nevi within the bronchus/airways have been reported
• Some studies hypothesise that these tumors may have originated from melanocytic metaplasia
• Other researchers have proposed that the tumor origin may be from an embryological abnormality that has taken place during fetal development

What are the Signs and Symptoms of Primary Melanoma of Lung?

The signs and symptoms of Primary Melanoma of Lung may include the following:

• Presence of a polypoid mass or nodule in the airways (or bronchus), termed endobronchial tumor
• A majority of the tumors are found in the lower lung lobes or upper (left) lobes
• Some tumors may be found in the trachea too; in such cases, they may appear ‘flattened’
• On an average, the tumors are 3-4 cm in size; a majority are solitary in nature
• The growth of the tumor mass may obstruct the airways
• Many individuals present with significant signs and symptoms
• The tumors can cause obstructive symptoms including chest pain, cough, breathing difficulties, and blood in sputum
• When metastasis is noted, it may result in weight loss, fatigue, and other systemic symptoms

Note: If solitary tumors are observed in the peripheral lung areas, then tumor metastasis from other sites should be suspected.

How is Primary Melanoma of Lung Diagnosed?

There are a variety of tests the healthcare provider may employ to diagnose Primary Melanoma of Lung, 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

A differential diagnosis may be necessary prior to establishing a definite diagnosis, by excluding the following cancers:

• Metastatic melanomas to the lung, which can be from the skin, eyes, or mucosal surfaces of the body
• Bronchial carcinoid tumors

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 Primary Melanoma of Lung?

The complications of Primary Malignant Melanoma of Lung may include the following:

• Severe obstruction of the airways in case of a large-sized tumor
• Most cases are diagnosed during the advanced cancer stages (when the cancer has spread to other body sites). Metastasis of the tumor to the following sites are known to take place:
  • Within the lungs
  • Brain
  • Bones
  • Lymph nodes
  • Adrenal glands
  • Gastrointestinal tract
  • Liver
• Recurrence of the tumor following its surgical removal

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 Primary Melanoma of Lung Treated?

The treatment of Primary Melanoma of Lung may involve the following:

• The treatment of choice is a complete surgical excision (removal of the tumor through surgery)
• Additionally, chemotherapy and/or radiation therapy may be necessary
• Follow-up care with regular screening and check-ups are important and encouraged

How can Primary Melanoma of Lung be Prevented?

Currently, there are no known methods to prevent the development of Primary Melanoma of Lung. Although there are no preventable measures for lung cancer, in general, various steps can be taken to help decrease the risk of its formation. These measures include:

• Complete smoking cessation and avoiding exposure to second-hand smoke: The risk for lung cancer decreases drastically following quitting or giving up smoking
• Physical activity: Individuals, who participate in a moderate amount of physical activity, may decrease their risk
• Adequate consumption of fruits and vegetables: A healthy diet, low in saturated fats and rich in many fruits and vegetables, may help decrease one’s risk for lung cancer
• Avoid exposure to certain materials and chemicals (including asbestos, arsenic, chromium, nickel, and tar): Individuals who work with such substances should follow proper usage principles and occupational safety instructions, since a prolonged exposure to harmful chemicals may increase the risk for lung cancer. This risk is multiplied in smokers who are exposed to these harmful chemicals
• Avoid exposure to radioactive gas: Radon, a radioactive gas, produced by the natural breakdown of uranium in soil and rocks, may develop to hazardous levels inside building spaces. Individuals exposed to excessive amounts of radon gas are vulnerable to lung cancer
• Limit alcohol consumption: Alcoholic beverages have been linked to increasing an individual’s risk for certain types of cancers, such as those affecting the lungs, mouth, throat, esophagus, breast, colon, and liver
• CT screening in high-risk groups can decrease the incidence of lung cancer, or at least help detect such cancers early. A low-dose CT scan is good to identify the tumors early. It is generally known that CT scans are about 3-4 times better than X-ray studies

What is the Prognosis of Primary Melanoma of Lung? (Outcomes/Resolutions)

• The prognosis of Primary Melanoma of Lung is generally guarded or poor, since most tumors are diagnosed at advanced stages
• The prognosis may markedly vary from one individual to another; some case study reports indicate a disease-free period of over 10 years in some individuals
• However, primary malignant melanomas have a better prognosis than secondary melanomas that have metastasized to the lungs
• The prognosis of lung cancer, in general, depends upon a set of several factors that include:
  • Stage of tumor: With lower-stage tumors, when the tumor is confined to site of origin, the prognosis is usually excellent with appropriate therapy. In higher-stage tumors, such as tumors with metastasis, the prognosis is poor
  • The size of the lung tumor: Individuals with small-sized tumors fare better than those with large-sized tumors
  • Overall health of the individual: Individuals with overall excellent health have better prognosis compared with those with poor health
  • Age of the individual: Older individuals generally have poorer prognosis than younger individuals
  • Individuals with bulky disease of the lung cancer have a poorer prognosis
  • Involvement of the lymph node, which can adversely affect the prognosis
  • Involvement of vital organs may complicate the condition
  • The surgical respectability of the tumor (meaning, if the tumor can be removed completely)
  • Whether the tumor is occurring for the first time, or is a recurrent tumor. Recurring tumors have worse prognosis compared to tumors that do not recur
  • Response to treatment of lung cancer: Tumors that respond to treatment have better prognosis compared to tumors that do not respond to treatment
  • Progression of the condition makes the outcome worse
• An early diagnosis and prompt treatment of the tumor generally yields better outcomes than a late diagnosis and delayed treatment

Additional and Relevant Useful Information for Primary Melanoma of Lung:

• 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