What is Arsenical Keratosis (Chronic arsenic toxicity)?
Arsenical keratosis is a skin condition that can lead to cancer, often seen in people suffering from long-term arsenic poisoning. It’s recognized by yellowish, hard skin bumps and patches that mainly appear on the hands and feet. Over time, these patches may increase in size and number, affecting the entire palm or sole, and rarely spread to other body areas. This condition can eventually progress to a type of skin cancer known as squamous cell carcinoma.
Often the first and most common sign of chronic arsenic poisoning is arsenical keratosis along with skin darkening. This makes it very important in helping doctors identify and treat arsenic poisoning early on. It can come along with harmless terms like skin darkening and nail changes (Mees’ lines), but it can also exist with cancerous lesions like Bowen’s disease, basal cell carcinoma, and squamous cell carcinoma. It’s very important to identify and remove the source of arsenic exposure as people with this condition are at high risk of developing disorders that affect multiple body systems, as well as other types of cancer.
What Causes Arsenical Keratosis (Chronic arsenic toxicity)?
Arsenical keratosis is a skin condition that results from ‘arsenicosis,’ a health problem caused by consuming arsenic above safe levels for at least six months, according to the World Health Organization (WHO). The time it takes for skin lesions to develop can range from 4 years to 40 years, depending on the type and amount of arsenic consumed, as well as the duration and frequency of exposure. Inorganic arsenic is a common element that has been classified as a class I human carcinogen by the International Agency for Research on Cancer. There are several known sources of arsenic exposure:
- Contaminated groundwater: This can be a source of arsenic if it’s used for drinking, cooking or watering crops.
- Food crops: If crops are grown in contaminated soil or watered with polluted water, they can contain arsenic. Whole-grain rice, for example, has been found to contain higher levels of arsenic than polished rice.
- Medications: Historically, medications like Fowler’s solution were used to treat various skin conditions and asthma, and arsenic-containing drugs were used to treat syphilis. Today, the FDA has approved the use of medicinal arsenic only for treating certain types of leukemia. Arsenic is also found in some Chinese herbal and Ayurvedic medicines.
- Occupational exposure: Arsenic is used in several industries including the manufacture of alloys, textiles, glass, paper, and wood preservation, among others. Workers in these industries, especially those involved in smelting and mining metals, may be exposed to greater amounts of arsenic. People living near these industries or mining activities may also be at risk.
- Tobacco: The tobacco plant can absorb arsenic from the soil and insecticides. Cigarettes made in the 1950s had high arsenic content but safe levels of arsenic in hand-made cigarettes, like bidis, have been difficult to regulate.
Risk Factors and Frequency for Arsenical Keratosis (Chronic arsenic toxicity)
Arsenic keratosis, a skin condition, is more often seen in countries where there is a high level of arsenic in the environment, especially in groundwater. Some of these countries include Bangladesh, India, Taiwan, Mexico, Chile, Argentina, Japan, and China. While this condition can affect people of any age, older individuals tend to have a higher rate of occurrence.
- Additionally, studies carried out in areas with a high arsenic presence indicate that men are more likely to develop arsenic keratosis than women when exposed to similar amounts of arsenic.
- This difference between men and women is generally attributed to the gender-based differences in how arsenic is processed in the body, a process known as biomethylation.
Signs and Symptoms of Arsenical Keratosis (Chronic arsenic toxicity)
Arsenical keratosis is a skin condition that develops slowly over time. The first signs are hard, horny growths on the hands and feet, especially on the palms and soles. These growths may be painful and can also cause the skin to crack. The growths start as small, yellowish patches or lumps, but can progressively increase in size and number over time. They can eventually become thick, wart-like plaques that cover large areas of skin. These growths can spread beyond the hands and feet to other parts of the body.
The severity of arsenical keratosis can vary and is often categorized as follows:
- Mild: Rough, slightly thickened skin or small lumps less than 2 mm in size.
- Moderate: Raised, wart-like, hard, corn-like lumps between 2-5 mm in size.
- Severe: Hard lumps more than 5 mm in size or large hardened plaques, with or without cracks in the skin.
Along with these skin changes, patients can also experience changes in skin color. Common changes include patches of darkened skin all over the body or in areas where skin folds. A unique characteristic is the appearance of either dark spots scattered throughout the body, described as a “raindrop” pattern, or lighter spots on a background of darkened skin, described as a “raindrop on a dusty road” pattern. Changes in the color of the mouth and distinctive white bands across the nails can also occur. These patients could also develop certain types of skin cancers.
Arsenical keratosis is not just a skin disease. It can also affect other body systems creating a multitude of symptoms, which include chronic liver disease, lung disease, nerve damage, heart disease, kidney disease, digestive problems, headaches, weakness, eye redness, and leg swelling. It’s also common for these patients to have diabetes and high blood pressure.
If a patient from an area known for arsenic pollution presents with thickened skin on the palms and soles, clinicians should look for signs of arsenical keratosis. These include the other skin changes and systemic symptoms discussed above. Confirmation of the diagnosis often requires lab tests. It’s also important to note, this condition often appears after years of arsenic exposure, so a detailed history is crucial to identify the source of arsenic exposure.
Testing for Arsenical Keratosis (Chronic arsenic toxicity)
To figure out if someone has CAT (chronic arsenic toxicity) and find out where the arsenic came from, a few tests are needed.
Firstly, the amount of arsenic in a person’s drinking water needs to be estimated. This involves collecting at least 50 milliliters of water in an special plastic container that’s been washed out with acid. The World Health Organization (WHO) says that there shouldn’t be more than 10 micrograms of arsenic per liter of drinking water. Countries like India and Bangladesh, however, have an older guideline that allows up to 50 micrograms per liter.
Next, the amount of arsenic in a person’s urine needs to be estimated. This can show if someone has been exposed to arsenic recently. Ideally, a sample of urine collected over 24 hours would be tested. But testing just a single urine sample, or the first pee of the day, also works. The amount of arsenic found in pee stays pretty stable during the course of a day. For accurate test results, patients should avoid eating seafood, which contains a harmless form of arsenic, for four days beforehand. Any test result with more than 50 micrograms of arsenic per liter of pee indicates recent arsenic exposure.
The arsenic amount in a person’s hair and nails also needs to be checked. This is done by washing the hair with a special shampoo and making sure the patient hasn’t used any hair dye. Then, hair samples and nail clippings are collected for testing. Any result with more than 1 milligram of arsenic per kilogram of dry hair, or more than 1.5 milligrams per kilogram of nails, indicates arsenic exposure over the last nine months.
Last of all, the suspected sources of the arsenic, like medications or pesticides, must be tested.
In cases where skin lesions have appeared, a medical test known as a histopathological examination will be done to see if cancer is present. This test, however, doesn’t provide a way to confirm the diagnosis.
Estimating the amount of arsenic in drinking water is usually the first step to take when trying to diagnose CAT. However, when the drinking water information isn’t accurate, like with people who move around a lot, it’s very important to analyze biological samples from the patient.
Treatment Options for Arsenical Keratosis (Chronic arsenic toxicity)
Once it’s been confirmed that a patient has been affected by arsenic and the source of exposure has been identified, the primary treatment focuses on preventing further contact with the arsenic. In many cases, patients with mild to moderate problems have seen improvements after doing this. Risk factors for this condition, which can potentially lead to cancer, are smoking and poor nutrition. Because of this, patients are recommended to quit smoking and eat a balanced, high-quality protein diet. There’s also a belief that taking antioxidants like vitamins A, C, and E can help prevent cancer.
The treatment of arsenic-caused skin abnormalities (arsenical keratosis) isn’t always necessary. The goal is to administer a kind of treatment that’s supportive and eases the patient’s discomfort. No one-size-fits-all treatment approach exists for arsenical keratosis — a treatment plan should be made based on the patient’s individual needs, the severity of the condition, any other health conditions they have, and their ability to manage pain. Treatment options that have been used over the years include:
* Freezing the skin growths (cryotherapy)
* Scrape and burn treatment (curettage and electrodessication)
* Carbon dioxide laser removal
* Topical medication to shed skin cells (keratolytic agents) such as salicylic acid (5 to 10%), urea (10 to 20%)
* Skin cream with imiquimod 5%
* Skin cream with 5-fluorouracil
* Oral retinoid medication
* Surgical removal
In patients with extensive skin abnormalities, a medication called acitretin, combined with skin-shedding medications, can be used. This treatment can help prevent cancers related to arsenic poisoning. Patients should be instructed to apply imiquimod cream either once daily for 6 weeks or 3-5 times per week for 8 weeks. It’s crucial for patients to have check-ups every six months, annual chest X-rays, and specific tests based on symptoms for the early detection of skin and internal cancers.
What else can Arsenical Keratosis (Chronic arsenic toxicity) be?
Verruca vulgaris simply means common warts.
Corns and calluses are thick, hardened layers of skin that develop when your skin tries to protect itself against friction and pressure.
Dermatophyte infection refers to a type of fungal infection of the skin, commonly known as ringworm.
Lichen planus is a condition that can cause swelling and irritation in the skin, hair, nails, and mucous membranes.
Hyperkeratotic eczema is a type of skin disorder that results in thickened, scaly skin.
Palmoplantar psoriasis refers to a chronic skin disease that causes red, scaly plaques on the palms of the hands and soles of the feet.
Porokeratosis punctata palmaris et plantaris is a rare skin disorder characterized by tiny, ring-shaped calluses on the palms of the hands and soles of the feet.
‘Clavi syphilitici’ is an old term used to describe lesions or sores on the skin that can occur in individuals with syphilis.
Inherited palmoplantar keratoderma refers to a group of skin conditions characterized by thickening of the skin on the palms of the hands and the soles of the feet. This is often passed down through families.
What to expect with Arsenical Keratosis (Chronic arsenic toxicity)
Arsenical keratosis is a condition that can potentially lead to skin cancer, more specifically, squamous cell carcinoma (SCC). Although uncommon, SCC that originates from arsenical keratosis tends to be more invasive and has a higher chance of spreading compared to SCC that develops from actinic keratosis.
Research has shown that individuals with arsenical keratosis are at an increased risk of later developing bladder and lung cancer.
Possible Complications When Diagnosed with Arsenical Keratosis (Chronic arsenic toxicity)
In severe cases of a skin condition known as arsenical keratosis, patients may experience widespread issues on the palms of their hands and the soles of their feet, including painful cracking. This can hugely impact their daily lives and overall quality of life.
Arsenical keratosis can sometimes be accompanied by a condition called a cutaneous horn. If the arsenical keratosis suddenly grows larger or harder, starts to crack, bleed or become inflamed, or if there’s an area of redness or ulceration around it, this suggest that it might have become malignant – usually a type of cancer called SCC.
Chronic arsenic toxicity (CAT) can impact many different organs in the body, sometimes leading to irreversible damage and chronic diseases. It can also increase the risk of developing cancers in the internal organs.
Typically, noticeable changes may include:
- Sudden increase in size of the affected area
- Hardening, or “induration”
- Cracking or “fissuring”
- Bleeding
- Inflammation
- Redness around the lesion, or “perilesional erythema”
- Ulceration
Preventing Arsenical Keratosis (Chronic arsenic toxicity)
Arsenical keratosis is an initial skin sign of a disorder known as CAT, which affects multiple systems in the body and can carry complications that may only show up years after exposure to arsenic. Therefore, in addition to making sure you’re no longer exposed to arsenic, it’s crucial to have regular medical check-ups. This ensures that any skin or internal symptoms of CAT get caught and treated early on.
Things like smoking and not getting enough nutrients can up your risk of developing arsenical keratosis. It’s important to take steps to reduce these risks. Moreover, patients should learn how to spot signs that arsenical keratosis may be getting worse, and if they notice anything unusual, they should seek medical attention promptly.
