Tuberculosis (TB): Practice Essentials, Background, Pathophysiology

What To Know About Tuberculosis And Skin Rash

Tuberculosis (TB) is a bacterial infection that usually affects the lungs but can spread to other parts of the body, including the skin. Once it reaches the skin, TB can cause a variety of lesions, most often on the legs, hands, or face.

In the United States, TB is often caused by bacteria called Mycobacterium tuberculosis (M. Tuberculosis). However, different bacteria can cause TB in other countries.

TB might be inactive and not cause symptoms, but if the bacteria multiply in the body, the symptoms can cause severe chest pain, a long-lasting cough that brings up blood and phlegm, and other symptoms of infection such as fever, chills, and appetite loss.

However, TB can spread to other organs and systems, including the glands, brain, bones, and skin.

This article explains the skin symptoms of tuberculosis.

Doctors refer to TB skin symptoms as cutaneous TB. Various different types of skin lesions can develop, including:

nodules

papules, which are small hard pimples or swellings on the skin

pustules

ulcers

plaques, which are rough, solid, flat-topped skin lesions

If tuberculosis infects the skin directly, it will generally appear up to 4 weeks after the bacteria enter the body.

At first, it forms a papule before developing into a shallow ulcer that is not painful. Nodules under the skin near lymph nodes are known as sporotrichoid lesions, and these may develop along with swollen lymph nodes, according to older 2013 information.

Types of skin TB

Different causes and types of cutaneous TB lead to different symptoms. These include:

Lupus vulgaris: This ongoing type of skin TB gets worse over time and occurs after reinfection by a different type of Mycobacterium to the first. It features small papules that merge into plaques known as apple-jelly nodules due to their jelly-like texture.

Miliary TB: This causes very small spots that start to kill tissue, becoming ulcers and abscesses. General sickness often occurs alongside these skin symptoms. Miliary TB can develop after TB spreads to the skin from the blood, largely in children and those with compromised immune systems.

Orificial TB: This causes shallow ulcers where the mucosal lining meets skin, known as mucocutaneous junctions, such as around the anus or nostrils. These ulcers generally point to advanced TB that has led to Mycobacterium reaching the mucocutaneous junctions.

Scrofuloderma: These firm lesions eventually become ulcers, but they do not cause pain. They can heal without treatment over several years, but scrofuloderma lesions can leave severe scars. Scrofuloderma spreads to the skin from a lymph node or bone infection, usually on the neck or jawline.

TB verrucosa cutis: This forms a purple or red-brown growth that resembles a wart. Most commonly, it develops on the hands, feet, elbows, and buttocks. Lesions can last for years but may resolve without treatment. Verrucosa cutis may develop after a person who already has TB receives a vaccination.

Sometimes, a primary TB infection of the skin will heal only for lupus vulgaris or TB verrucosa cutis to develop in the same location.

Some types, such as lupus vulgaris, may also increase the risk of skin cancers such as squamous cell carcinoma for 10% of people. This may develop in cutaneous TB scars around 25 to 30 years after the original infection.

M. Tuberculosis may directly enter the skin or spread there via the bloodstream. When TB enters the skin directly, it may be a rare response to an injected vaccine, such as the Bacille Calmette-Guerin (BCG) vaccine.

Tattoos, piercings, or other skin injuries can also lead to TB passing the skin barrier.

TB can also spread to the skin from underlying focal points of infection, such as a lymph node or bone.

Most often, TB spreads through the air when an individual with TB speaks or coughs. M. Tuberculosis can stay airborne for several hours and spreads more readily in places with little circulation, such as a closed vehicle. People with a higher risk of acquiring M. Tuberculosis may include:

people who regularly come into close contact with those who have symptoms of TB

residents of or visitors to a country or community with a high prevalence of TB

those in crowded communities, such as prisons, long-stay hospitals, and care homes for older adults

individuals who work in healthcare settings such as hospitals

However, even in regions that experience TB more often than the United States, including China, the Indian subcontinent, and sub-Saharan Africa, fewer than 0.1% of people develop cutaneous TB.

This equates to around 1% to 2% of people who experience symptoms of TB outside the lungs. It may be more common in global regions with a higher prevalence of HIV or other conditions that reduce the ability of the immune system to counter infections.

People can take a course of TB medication to treat active or inactive TB. Treating inactive TB can prevent symptoms from occurring. This usually involves taking a combination of medications for 3 to 9 months, depending on the treatment plan.

Medications for TB include:

ethambutol

isoniazid

pyrazinamide

rifampicin

moxifloxacin

rifapentine

However, drug-resistant TB requires treatment with different medications.

Some lesions, such as lupus vulgaris or scrofuloderma, may require surgical removal. Lupus vulgaris often gets worse without treatment. Tuberculosis verrucosa cutis and scrofuloderma may heal without treatment, but they can also worsen.

Even though some skin lesions are slow-healing, full recovery often occurs after using muti-drug therapy. Reconstructive plastic surgery may also be necessary to address damage by some lesions.

TB can enter the skin directly or through the blood, lymph nodes, or bones if it moves beyond the lungs. A range of conditions can cause severe nodules, ulcers, pustules, and plaques that vary in progression, outlook, and self-healing ability.

Cutaneous TB is very rare, even in people who develop TB outside of the lungs. It is more likely in people who have compromised immune systems.

Treatment includes multi-drug therapy, and doctors may recommend surgically removing lesions for some types of cutaneous TB.

History Of Tuberculosis

Tuberculosis is a highly contagious disease caused by the bacteria Mycobacterium tuberculosis (M. Tuberculosis), which is believed to be present in nature for at least 15,000 years.

Mycobacterium tuberculosis is a pathogenic bacterial species in the family Mycobacteriaceae and the causative agent of most cases of tuberculosis - Illustration Credit: Tatiana Shepeleva / Shutterstock

Tuberculosis has been known to mankind since ancient times. It is believed that the genus Mycobacterium was present in the environment about 150 million years ago, and an early variant of M. Tuberculosis originated in East Africa about 3 million years ago. A growing pool of evidence suggests that the current strains of M. Tuberculosis is originated from a common ancestor around 20,000 – 15,000 years ago.

Studies on Egyptian mummies (2400 – 3400 B.C) revealed the presence of skeletal deformities related to tuberculosis, such as characteristic Pott's deformities. However, no evidence of tuberculosis was found in Egyptian papyri. The description of tuberculosis was initially found in India and China as early as 3300 and 2300 years ago, respectively. Moreover, tuberculosis was mentioned in the Biblical books using the Hebrew word 'schachepheth' to describe tuberculosis.

In the Andean states, the first pre-Columbian evidence of tuberculosis was observed in Peruvian mummies, indicating the presence of the disease before the European colonization of South America.

Tuberculosis was well documented in the Ancient Greece as 'Phthisis' or 'Consumption'. In Book I, Of the Epidemics, Hippocrates described the symptoms of Phthisis, which are very similar to the common characteristics of tubercular lung lesions.

A Greek physician, Clarissimus Galen, who became the physician of the Roman Emperor Marcus Aurelius in 174 AD, described the symptoms of tuberculosis as fever, sweating, coughing, and blood-stained sputum. He also suggested that fresh air, milk, and soy beverages should be effective treatments for tuberculosis.

In Roman times, tuberculosis was mentioned by Celso, Aretaeus of Cappadocia, and Caelius Aurelianus. However, it remained unrecognized at that time. After the decline of the Roman Empire in the 5th century, a vast pool of archeologic evidence of tuberculosis was found throughout Europe, indicating that the disease was widespread in Europe during this time.

In the Middle Ages, a new clinical form of tuberculosis was described as scrofula, a disease of cervical lymph nodes. In England and France, the disease was known as 'king's evil', and there was a popular belief that it could be treated with the 'royal touch'. The practice of the 'royal touch' established by English and French kings continued for several years. Queen Anne was the last British monarch to employ this method for healing.

A French surgeon, Guy de Chauliac, proposed the first medical intervention for treating tuberculosis. He advised the removal of the scrofulous gland as a treatment option.

An Italian physician, Girolamo Fracastoro, first described the contagious nature of tuberculosis clearly in the 16th century.

In 1679, Francis Sylvius provided the exact pathological and anatomical description of tuberculosis in his book 'Opera Medica'. In 1720, a British physician, Benjamin Marten, first described the infectious origin of tuberculosis in his publication entitled 'A new theory of Consumption. In the 17th and 18th centuries, the terms 'Consumption' and 'phthisis' were used to describe tuberculosis.

In 1819, a French physician, Theophile Laennec, identified the pathological signs of tuberculosis, including consolidation, pleurisy, and pulmonary cavitation. He also identified that M. Tuberculosis can infect the gastrointestinal tract, bones, joints, nervous systems, lymph nodes, genital and urinary tracts, and skin (extra-pulmonary tuberculosis), in addition to the respiratory tract (pulmonary tuberculosis).

Johann Schonlein first coined the term 'tuberculosis' in 1834. At the beginning of the 19th century, there was a scientific debate about the exact etiology of tuberculosis. Many theories existed at that time, describing the disease as infectious, hereditary, or a type of cancer.

In 1843, Philipp Friedrich Hermann Klencke, a German physician, experimentally produced the human and bovine forms of tuberculosis for the first time by inoculating extracts from a miliary tubercle into the liver and lungs.

In 1854, sanatorium cure for tuberculosis was introduced by Hermann Brehmer, a tuberculosis patient, in his doctoral thesis. He mentioned that a long-term stay in the Himalayan mountains helped cure his tuberculosis.

A French military surgeon, Jean-Antoine Villemin, experimentally proved the infectious nature of tuberculosis in 1865. He inoculated a rabbit with fluid taken from a tuberculous cavity of a person who died of tuberculosis.

A German physician and microbiologist, Robert Koch, successfully identified, isolated, and cultured the tubercle bacillus in animal serum. Afterward, he produced animal models of tuberculosis by inoculating the bacillus. In 1882, his groundbreaking work was published in the Society of Physiology in Berlin.

Discovery of diagnostic methods

In 1907 – 1908, Clemens von Pirquet and Charles Mantoux developed the tuberculosis skin test, in which tuberculin (extracts of the tuberculosis bacillus) is injected under the skin, and the body's reaction is measured. In recent years, advancements in tuberculosis diagnosis have included interferon-gamma release assays, which are whole-blood tests to detect M. Tuberculosis infection.

Tuberculosis bacillus in the lungs. Tuberculosis is caused by the bacterium Mycobacterium tuberculosis. Image Credit: Juan Gaertner / Shutterstock

Discovery of vaccine

A pioneering work toward the prevention of tuberculosis was made by Albert Calmette and Jean-Marie Camille Guerin, who developed the Bacille Calmette-Guérin (BCG) vaccine in 1921.

Discovery of therapeutic agents

Besides preventive vaccines, a major breakthrough in tuberculosis treatment occurred with the discovery of antibiotics. In 1943, a tuberculosis antibiotic streptomycin was developed by Selman Waksman, Elizabeth Bugie, and Albert Schatz. Afterward, Selman Waksman received the Nobel prize in 1952.

In the recent era, four antibiotics namely isoniazid (1951), pyrazinamide (1952), ethambutol (1961), and rifampin (1966) are used to effectively treat tuberculosis. With the improvement in diagnostic procedures, therapeutic interventions, and preventive strategies, the World Health Organization (WHO) has committed to eradicate M. Tuberculosis by the year 2050.        

Further Reading

Tuberculosis Outbreak In Kansas City

An outbreak of tuberculosis within Kansas City in the United States has been ongoing since Jan. 2024 and has highlighted new trends of TB in the United States. According to March 2025 U.S. Centers for Disease Control and Prevention data, the TB rate in Kansas increased by 148% from 2024–25.

This alarming upward trend has been accompanied by an increased number of cases across the United States. In fact, in March 2025, data from the CDC showed more than 10,300 reported TB cases in 2024. This is indicative of an 8% increase in cases since 2023 and the highest number of reported TB cases in the US since 2011. 

The incidence of tuberculosis cases is spreading beyond Kansas City, with a new case reported in a Chicago high school on Monday.

Tuberculosis is a disease primarily caused by the pathogenic bacteria mycobacterium tuberculosis, but can also be caused by other mycobacteria. These rod-shaped microorganisms can be found in soil and water, and are responsible for illnesses such as tuberculosis and leprosy. There are two types of mycobacteria that can cause tuberculosis in humans: mycobacterium tuberculosis and mycobacterium bovis. However, tuberculosis is most commonly caused by mycobacterium tuberculosis.

Tuberculosis is spread through respiratory droplets in the air that can come from speaking, coughing or sneezing. When an individual becomes infected with tuberculosis, the bacteria most commonly spread to the lungs, replicate and form large masses called tubercles. These tubercles can break down lung tissue and ultimately can cause permanent damage to the lungs if untreated. 

This is why timely diagnosis and effective treatment are vital when it comes to tuberculosis. Currently, there are two regimens that require anywhere from four to nine months of treatment that can lead to a 100% cure. Other considerations may further impact treatment, including the potential for individuals to have drug-resistant tuberculosis, which requires other treatment plans that may require years. 

A final consideration in understanding tuberculosis is the difference between latent and active infection. When a person has an active TB infection, they will be symptomatic, able to transmit the disease and in need of immediate treatment. On the other hand, latent infections are asymptomatic and unable to transmit the disease. However, without treatment, these latent cases may become active over time, making them potentially dangerous.

On Feb. 11, the Kansas City area had 67 active reported cases, 79 latent cases and two deaths recorded. As mentioned by Jill Bronaugh, a spokesperson from the Kansas Department of Health and Environment, the department is "working with and following the guidance of the CDC."

Each patient is being screened and contact traced, and testing is being provided for free. In terms of access to treatment, the state department has promised that treatment will be given to every patient regardless of their insurance status.

Overall, protocols are continuously being put into place to work towards ending this outbreak across Kansas and in the United States. With continued interventions and implementations, it is hoped that this outbreak will be under control in the foreseeable future.

---