How Fungal Infections in the Lungs Mimic Cancer

Research has shown that fungal lung infections can possibly be mistaken for lung cancer. Fungal lung infections may appear similar to lung cancer in both the symptoms they cause and how they look on imaging, such as computed tomography (CT) or chest X-ray.

Among the most common fungal infections that mimic primary lung cancers are aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, mucormycosis, and paracoccidioidomycosis.

This article will explore how the symptoms of fungal lung infections and lung cancer can overlap, and how to tell the difference.

Fungal Infections in Lungs 

There are multiple fungi that can cause an infection in the lungs. The following are the most common infections. Learn their symptoms, how they are diagnosed, and how they are treated. 

Aspergillus/Aspergillosis

Aspergillosis is the infection caused by the fungus Aspergillus. This fungus is found in many places, such as in plants and soil, and is commonly found inside homes, in the dust, air ducts, and even in carpets.

When Aspergillus spores are breathed in, they can stay in the sinus or lung cavities and develop an infection. Symptoms of aspergillosis include:

• Shortness of breath
• Cough
• Wheezing
• Fever
• Chest pain
• Coughing up blood

In imaging studies, this fungi can show up as a nodule, or “spot” on the lung. These nodules may progress into larger patches of nodules as the infection continues.

To diagnose this infection, a sample of tissue may be tested. A biopsy of sputum cultures or cultures that are taken from deeper in the lungs may be necessary.

Biopsies can be done through bronchoscopy—a procedure that involves inserting a narrow tube or scope with a light and camera on the end through the nose or mouth and guiding it down the windpipe to get an internal view of the lungs.

Blastomycosis

Blastomycosis is caused by the fungus Blastomyces dermatitidis. This is most often found in soil near water or in wooded areas, but can also be found indoors, such as in basements or attics.

If this fungus is inhaled, it can cause pneumonia, with symptoms such as fever, cough, and shortness of breath. The infection can also spread beyond the lungs and cause symptoms in the skin, bones, and urinary tract.

On imaging, it can vary in appearance, which can make it difficult to diagnose. The ultimate diagnosis is made by culturing sputum (a mixture of saliva and mucus coughed up from the respiratory tract) from the lung to determine the cause of infection.

Coccidioidomycosis

Coccidioidomycosis is also referred to as valley fever. It is caused by the fungus Coccidioides. This fungus is most often found in the soil in the southwestern United States and Mexico. It can enter the lungs by breathing in large amounts of dust in these areas.

This infection presents with symptoms of pneumonia, but may also cause headaches and skin rash.

This infection can be diagnosed through a blood test or through a tissue sample from the lungs. 

Cryptococcosis

Cryptococcosis is an infection caused by the fungus Cryptococcus neoformans. This is a fungus found throughout the world, in bird droppings, wooded areas, in trees, and in the soil. The spores of the fungus can enter the body and develop an infection in the lungs. However, it has the potential to cause an infection in the nervous system as well.

If the infection is in the lungs, it presents with respiratory symptoms. If the infection is in the nervous system, it may cause symptoms including:

• Headache
• Fever
• Neck pain
• Nausea, vomiting
• Confusion
• Light sensitivity

Cryptococcosis can be diagnosed through blood or tissue samples of the lungs or cerebral spinal fluid. Once diagnosed, treatment is based on how severe the infection is.

Histoplasmosis

Histoplasmosis is the infection caused by the fungus Histoplasma. In the United States, it is most commonly found in the central states, but it can also be found in other countries around the world.

Symptoms of histoplasmosis can include:

• Fever
• Cough
• Tiredness
• Headache
• Body aches 
• Chest pain

Blood or urine samples can be used to diagnose histoplasmosis. In some cases, a sample of tissue or a culture of the fluid from the lungs may be needed. Some people do not require treatment, and the infection can go away without intervention. Others may require months of antifungal medications.

Mucormycosis

Mucormycosis is an infection from molds called mucormycetes. These can be found in decaying wood, soil, leaves, and compost piles. The infection can occur in multiple areas of the body, including the lungs, sinuses, gastrointestinal tract, and skin.

Mucormycosis is diagnosed through imaging the areas experiencing symptoms, by CT or X-ray. Tissue samples or cultures also need to be taken.

Mucormycosis often requires treatment with intravenous antifungal medications, and possibly even surgery to remove the infected areas.

Paracoccidioidomycosis

Paracoccidioidomycosis is an infection caused by the fungus Paracoccidioides, and is most often found in the soil of Central America and South America.

Symptoms of paracoccidioidomycosis can include: 

• Mouth sores or ulcers
• Fever
• Weight loss
• Cough
• Enlarged lymph nodes
• Enlarged spleen
• Enlarged liver

Imaging, lab tests such as culture, and tissue biopsy are used to make a diagnosis. To treat this condition, antifungal medications are usually given for about one year.

Primary Lung Cancer 

When cancer starts in the lungs, it is referred to as primary lung cancer. It is further classified into types of lung cancer based upon the cells in which the cancer originated. Types of primary lung cancer include:

• Non-small cell lung cancer
• Adenocarcinoma
• Squamous cell
• Large cell
• Small cell lung cancer
• Carcinoid tumor

Symptoms of a primary lung cancer may include:

• Cough
• Chest pain
• Shortness of breath
• Hoarse voice
• Weight loss
• Coughing up blood
• Feeling tired

Lung cancer is often found through imaging tests, such as X-ray, CT, magnetic resonance imaging (MRI), or positron emission testing (PET). Then biopsy of the suspicious tissue needs to be taken to be evaluated for the presence of cancer cells, and determine the type of cancer cells, if they are present, to confirm a diagnosis. 

Once a diagnosis is made and the imaging tests are done, the cancer is given a stage, based on how large it is and if it has spread to other areas of the body. 

Treatment of lung cancer is dependent upon the stage, but may include surgery, radiation, chemotherapy, immunotherapy, or a combination of these options. 

Fungal Infections in Lungs and Cancer: Common Symptoms 

When an individual suddenly develops symptoms such as fever, chest pain, and cough, the healthcare provider may initially prescribe antibiotics. However, if symptoms do not improve after a course of antibiotics, they may undergo further imaging tests to determine the source of the symptoms. 

These imaging studies may show nodules or other abnormal findings in the lungs, and these findings may appear suspicious for lung cancer. If this is the case, they may be referred to a lung doctor (pulmonologist) for further evaluation and possibly a biopsy. A biopsy can determine if the suspicious area found on the imaging is in fact lung cancer, or if it is an infection.

A Word From Verywell

It's important to notify your healthcare team if you develop symptoms that could potentially be related to a fungal infection. Getting an infection treated promptly is essential to preventing it from spreading to other areas of the body and causing additional complications.

If you’re living with lung cancer and you have symptoms of a fungal infection, discuss this with your cancer care team. Never hesitate to advocate for yourself if you want further imaging or testing to determine a cause for your symptoms.