Finger Clubbing: Symptoms, Causes, Lung Diseases, and Treatment

Clubbing is a clinical finding characterized by widening and thickening of the nail beds and marked rounding of the fingertips. It usually appears as an indicator of chronic diseases and is not a disease on its own, but an external manifestation of an underlying systemic condition.

The most common causes of clubbing include chronic lung diseases, lung cancer, bronchiectasis, and cystic fibrosis. Conditions that cause long-term hypoxia lead to an increase in connective tissue at the fingertips. In addition, certain heart diseases and cyanotic heart defects may also cause this condition.

The symptoms of clubbing are observed as the disappearance of the angle between the nail and the finger, spongy softening of the nail bed, and widening of the fingertips. In advanced cases, the nails take on a shinier and more convex appearance. The changes are usually painless but may be progressive.

The treatment of clubbing is based on controlling the underlying disease. There is no specific treatment that directly eliminates clubbing. Following medical or surgical intervention aimed at the cause, the findings may regress or become stable. Early diagnosis is important in terms of prognosis.

What Is Clubbing and What Does It Look Like?

Clubbing is essentially a condition in which the soft tissue at the tips of the fingers and toes swells and widens, and the nail plate becomes convex in order to adapt to the underlying swelling. The most important point that should be emphasized here is this: This growth does not occur in the bone. In other words, the bone at the fingertip does not grow or lengthen. The event is entirely due to an increase, edema, and increased vascularity of the soft tissue between the nail bed and the bone.

When you look at a normal, healthy finger from the side, you see a slight depression or an angle between the root where the nail emerges from the skin and the nail surface. This natural curve, which we call the Lovibond angle, gives the nail its elegance. However, when clubbing begins, the tissue beneath the nail root swells and fills this natural depression. As the process progresses, the base of the nail rises, flattens, and eventually becomes convex outward.

There are some comparisons we use to describe this physical change. The fingertips become rounded in a way that resembles a drumstick. The nails, on the other hand, take on the appearance of the convex glass found on old-fashioned watches, known as “watch-glass nails.” Not only the appearance but also the sensation on touch changes. Normally, when you press on the nail root, you feel a firm surface because the nail is close to the bone. However, in clubbing, since the tissue in between becomes spongy, when you press on the nail, it feels as though the nail is floating or moving over the underlying bone. We call this the “floating nail” phenomenon, and feeling this during examination is quite distinctive for us.

The main physical changes seen in the development of clubbing are as follows:

• Loss of the natural angle at the nail root
• Widening of the fingertip into a drumstick shape
• The nail plate becoming convex like a watch glass
• Softening of the nail bed and a spongy sensation
• The skin around the nail appearing shiny and tense
• The fingertip feeling warmer than normal

Why Does Clubbing Occur?

The question of how a disease in the lung can change the shape of the fingers is an issue that the medical world has pondered for many years. At the point we have reached today, the most logical and scientific mechanism explaining this condition is related to a disruption in the circulation of blood cells. We call this the “Megakaryocyte and Platelet Theory.” Let us explain it in language everyone can understand.

In our body, blood cells are produced in the bone marrow. Platelet cells, which enable clotting, are in the form of giant cells called “megakaryocytes” when they first emerge from the bone marrow. These giant cells enter the circulation and reach the lungs. In a healthy person, the lungs serve as an excellent filter in addition to gas exchange. The thin capillaries of the lungs trap these giant cells and break them down into small, normal-sized platelets. In other words, the lung is like a filter where the blood is mechanically processed:

However, in certain diseases relevant to thoracic surgery, this filtering mechanism is disrupted. When tumors such as lung cancer disturb the vascular structure or in certain congenital vascular diseases called shunts, blood passes directly into the systemic circulation without going through the lung filter or being filtered. At that point, those giant cells that should have been broken down enter the systemic circulation intact. Due to the physics of blood flow, these large and cumbersome cells are carried to the most distant points of the body, namely the finest capillaries at the tips of the fingers and toes. The fingertips are a kind of dead end, and these giant cells become trapped there.

These cells that accumulate at the fingertip do not simply remain there; they also release very powerful chemical signals. In particular, they release substances called “Growth Factors” such as PDGF and VEGF into the environment. These substances are like a kind of fertilizer that gives tissues the command to “grow.” They increase vascular permeability in the area, stimulate connective tissue cells, and trigger collagen production. As a result, vascularity increases at the fingertip, the tissue swells, and the characteristic clubbing appearance emerges. In fact, this swelling in your fingers is a growth response of the vessels at the farthest points of your body to obstruction and lack of oxygen.

Can Clubbing Be Detected with the Schamroth Test?

Our patients sometimes do not notice the changes in their fingers because this process usually progresses slowly and insidiously and does not cause pain. However, there is a very simple test that you can perform on your own at home, requires no equipment, and is also frequently used by us in the outpatient clinic: the Schamroth Window Test.

The logic of this test is to check for the presence of the natural angle at the nail root. To perform the test, you need to use the same fingers of both hands, usually the index fingers. Bring your hands to eye level and place your two index fingers together so that the backs of the nails touch each other. When you press your nails firmly together, carefully look toward the nail roots, in other words, the point where the nail meets the flesh.

In a healthy structure, when the two nail roots come together, a very small diamond- or lozenge-shaped gap should remain between them. You can see light passing through this gap. If you can see this “light window,” the test is negative, meaning your finger structure is probably normal. However, in clubbing, since the angle at the nail root becomes flattened and the tissue swells, this gap closes completely. When you bring the two fingers together, no gap remains between them and no light passes through.

The points you should pay attention to when performing the Schamroth test are as follows:

• The hands should be held at eye level
• The same fingers should be brought opposite each other
• The backs of the nails should fully touch each other
• The first joint should be kept straight without bending
• Having light in the background makes visibility easier

If you cannot see that small diamond-shaped gap, this is one of the clearest indicators of developing clubbing and it would be beneficial to consult a specialist:

Which Diseases Can Clubbing Be a Sign Of?

In approximately 80% of patients with clubbing, the source of the problem is inside the chest cavity. This is a very high rate. The remaining 20% may be caused by heart diseases, digestive system problems such as ulcerative colitis and cirrhosis, or hormonal causes such as thyroid disorders. Sometimes, there may even be familial, idiopathic cases of clubbing that occur entirely as a genetic inheritance without any disease. However, for us thoracic surgeons, clubbing is a sign of a serious pathology in the lung until proven otherwise.

• Lung Cancers:

If clubbing begins later in an adult whose fingers were previously normal, the first and most alarming possibility that comes to mind is lung cancer. Clubbing is especially common in adenocarcinoma and squamous cell cancer types, which belong to the “non-small cell lung cancer” (NSCLC) group. In fact, studies show that nearly half of patients diagnosed with lung cancer have varying degrees of clubbing. This finding may sometimes appear months before typical cancer symptoms such as cough, shortness of breath, or bloody sputum. In this respect, clubbing may serve as a life-saving early warning system. We also frequently encounter this finding in cancer of the lung membrane, called “mesothelioma,” which usually develops due to asbestos exposure.

• Chronic Infections:

Diseases in which the lung tissue remains inflamed for a long time, becomes damaged, and continuously produces purulent material are conditions in which clubbing develops most rapidly and most prominently. The body is in a constant state of fighting infection, and this disrupts the vascular structure at the fingertips.

• Interstitial Lung Diseases:

In diseases such as “pulmonary fibrosis” (IPF), in which the lung tissue loses its elasticity and becomes stiff, oxygenation of the blood is chronically impaired. Long-term low oxygen levels, or hypoxia, trigger dilation of the vessels at the farthest points of the body. In these patients, clubbing usually follows a course parallel to the progression of the disease and may be an indicator of the loss of lung capacity.

The main diseases that cause clubbing in the field of thoracic surgery are as follows:

• Lung cancer (Especially Adenocarcinoma)
• Cancer of the lung membrane (Mesothelioma)
• Bronchiectasis (Permanent widening of the bronchi)
• Lung abscess (Accumulation of pus in the lung)
• Empyema (Accumulation of inflammation between the lung membranes)
• Cystic Fibrosis
• Idiopathic Pulmonary Fibrosis (Hardening of the lung)
• Pulmonary tuberculosis

How Do Doctors Diagnose Clubbing?

When you consult us with a complaint or suspicion of clubbing, the deformity in the fingers is only a starting point for us. Our main aim is to find the fire producing this smoke. After examining your fingers, we conduct a detailed inquiry: When did this change begin? Do you smoke? Is there anyone in your family with a similar finger structure? Are there accompanying symptoms such as cough, weight loss, or joint pain?

Following this initial consultation, we use technological imaging methods to view the inside of the chest cavity in detail. A standard chest X-ray may be taken as the first step, but this method is often insufficient. It may not be possible to see a small tumor or a lesion hidden behind the heart on an X-ray. Therefore, for us, the “gold standard” diagnostic method is Computed Tomography (CT).

With tomography, we view the lungs by obtaining thin-slice sections. In this way, we can clearly see millimetric nodules, the structure of the bronchi, infection foci, or changes in the chest wall. If we detect a suspicious mass on tomography, the nature of the process changes and more advanced examinations come into play.

At this stage, the nuclear medicine examination called Positron Emission Tomography (PET/CT) comes into play. We scan the entire body after giving the patient a labeled sugar molecule. Since cancer cells grow rapidly, they love sugar and attract it to themselves. In this way, we understand whether that suspicious mass is active, its likelihood of being malignant, and whether the disease has spread to another organ.

Another important part of the diagnostic process is the “Bronchoscopy” procedure. We enter through the patient’s airway with a thin, flexible tube equipped with a light and camera and examine the inside of the lungs and the bronchial tree in real time. If there is a tumor inside the airways, we see it and take a biopsy sample from there. Today, with advanced methods such as navigational bronchoscopy, we can even reach lesions in the farthest corners of the lung.

The methods we use in the diagnostic process are as follows:

• Physical examination and Schamroth test
• Chest X-ray
• Thoracic Computed Tomography (CT)
• PET/CT scan
• Fiberoptic Bronchoscopy
• Pulmonary Function Tests
• Blood gas analysis

How Is Clubbing Treated?

One of the questions our patients ask most frequently is: “Doctor, will my fingers return to normal?” or “Is there a cream or medication for my fingers?” The basic principle that needs to be understood here is this: We do not treat the clubbing itself, but the disease causing it. The change in the fingers is a result, not the cause. Therefore, no cosmetic operation or local treatment is applied to the fingers. Our goal is always to eliminate the main source.

Our treatment strategy is shaped entirely according to the underlying disease. If the source of the problem is lung cancer, our priority is to remove that tumor. If there is a lung abscess or a chronic infection, the inflammation must be drained and the infection brought under control.

So, do the fingers return to their former state once the underlying disease is treated? The answer to this question varies depending on the situation. If the clubbing developed acutely, meaning it appeared rapidly after an abscess or empyema, the edema in the fingers resolves quickly once the infection is treated, and the fingers may largely return to their former slender appearance. After lung cancer surgery, once the tumor is removed from the body, the levels of growth factors decrease, and the feeling of fullness, throbbing, and pain at the fingertips usually disappears. However, in chronic cases that have continued for many years and in which changes in the bone tissue have become established, the shape of the fingers may not return completely to normal. Nevertheless, treatment of the underlying disease stops the deformity from progressing further.

Which Surgical Methods Are Used for Clubbing?

In thoracic surgery, we now use highly advanced surgical techniques in the treatment of lung diseases that cause clubbing. Our aim is to free the patient from the disease while causing the least harm and ensuring the fastest recovery.

In the past, thoracic surgery brought to mind large incisions, separated ribs, and long recovery periods. Today, thanks to technology, “minimally invasive surgery” methods are at the forefront.

• VATS (Video-Assisted Thoracoscopic Surgery):

In this method, commonly known as “minimally invasive surgery,” we do not make a large incision in the rib cage. We usually enter through one or several small openings, or ports, measuring 1 to 3 centimeters, using a camera and special surgical instruments. By projecting the camera image onto a large screen, we remove the tumor or the diseased portion of the lung. Since the ribs are not cut or forced apart with a retractor, postoperative pain is much less and cosmetic results are excellent.

• Robotic Surgery (RATS):

This is the most advanced point reached by minimally invasive surgery. As the surgeon, we do not stand beside the patient; we sit at a console in the operating room. We control the robotic arms with three-dimensional, high-resolution imaging. The robotic arms have a much greater range of rotation than the human wrist and do not tremble. This allows us to work with millimetric precision in very narrow and risky areas such as behind the heart and around the vessels. Robotic surgery provides a major advantage especially in lymph node dissection and delicate dissections.

• Open Surgery (Thoracotomy):

Although we prefer minimally invasive methods, we may sometimes need to perform open surgery due to the size or location of the tumor or because of adhesions. In this method, the procedure is performed by entering between the ribs. It is a safe and effective method, but the recovery period is slightly longer compared with minimally invasive methods.

The specific surgical procedures we perform vary according to the extent of the disease:

• Lobectomy: The complete removal of the diseased lobe of the lung, which is the procedure we most commonly perform in lung cancer.
• Segmentectomy: If the tumor is very small and detected early, only that small segment is removed in a lung tissue-preserving procedure.
• Pneumonectomy: Very rarely, if the tumor has involved the entire lung, it may be necessary to remove the whole lung on one side.
• Decortication: In inflammations of the lung membrane, or empyema, this is the procedure of peeling away the thickened membrane covering the lung that has become like an orange peel. In this way, the trapped lung is freed again and can expand.

What Is the Recovery Process Like After Surgery?

Undergoing thoracic surgery is undoubtedly a stressful process for patients. However, thanks to modern methods, this process has now become much more comfortable. The recovery period varies according to the type of surgery performed and the patient’s general performance status.

If the surgery is performed using a minimally invasive method, such as VATS or robotic surgery, we usually begin walking our patients on the evening of the operation or the following morning. Early movement is very important for expanding the lungs and reducing the risk of complications. The average hospital stay is between 3 and 5 days. The patient is discharged after the tube called a drain, which removes fluid and air from inside, is taken out.

In open surgeries, since muscle and bone tissue are affected more, pain control becomes slightly more important and the hospital stay may extend to 5-7 days. However, with advanced pain relief methods such as epidural catheters, we try to keep our patients’ comfort at the highest possible level.

After returning home, we expect our patients to be able to resume light daily activities within approximately 2 to 4 weeks. A full return to work and active life is usually possible by the end of the first month. During this period, performing breathing exercises, staying away from smoking, and maintaining a healthy diet are the most important factors that accelerate recovery.

The points that should be taken into consideration after surgery are as follows:

• Performing the prescribed breathing exercises (Triflow) regularly
• Staying active with short and frequent walks
• Taking painkillers on time and regularly
• Eating a diet rich in protein and vitamins
• Keeping the wound area clean and dry
• Staying completely away from cigarette smoke

Frequently Asked Questions

Prof. Dr. Alper Fındıkçıoğlu

Prof. Dr. Alper Fındıkcıoğlu graduated from Istanbul University Faculty of Medicine and completed his thoracic surgery residency at Dr. Siyami Ersek Hospital. He began his academic career at Başkent University in 2005; he received the title of associate professor in 2014 and professor in 2022. He has extensive experience in lung cancer, chest wall diseases, and minimally invasive surgery. Since 2024, he has been continuing his professional work at Acıbadem Hospital.