Vitiligo and Associated Diseases

The topic of diseases associated with vitiligo is often mentioned when discussing this condition. The analysis of associated diseases — also referred to as “comorbidity” in scientific terminology — can in fact provide valuable information about a specific disease, helping to increase our knowledge on the subject and therefore supporting progress in treatment.

What Is Meant by “Associated Diseases”?

In the medical field, associated diseases (or comorbidities) refer to the coexistence of multiple different conditions in the same individual. The definition may refer to two or more diseases that coexist simultaneously but independently from one another, or to diseases that appear secondary to the onset of an underlying condition. In particular, understanding associated diseases is useful for better evaluating the cost-benefit ratio when choosing which treatment to adopt for a specific pathological condition — in other words, determining whether the risks and costs of an aggressive therapy outweigh the benefits the patient may obtain.

In patients affected by vitiligo, the presence of other diseases can sometimes be observed, most of which are autoimmune in nature. These include, specifically, Hashimoto’s Thyroiditis, celiac disease, type 1 diabetes, and atrophic gastritis. Let’s examine each of these conditions in more detail:

Hashimoto’s Thyroiditis

Hashimoto’s thyroiditis is an autoimmune disease that causes the immune system to attack thyroid cells. Although this attack may not initially cause a reduction in thyroid gland function, the gland must still be monitored through specific blood tests and an annual thyroid ultrasound examination.

During the diagnostic process, an effective method is to perform blood tests aimed at identifying the presence of antibodies directed against thyroid components, particularly thyroglobulin and thyroid peroxidase.

If these tests reveal the presence of the aforementioned autoantibodies, the diagnosis of Hashimoto’s thyroiditis is certain. In this case, it is advisable to complete the diagnosis with a thyroid ultrasound, which usually reveals a heterogeneous ultrasound pattern.

Many years may pass between antibody positivity and the actual onset of Hashimoto’s thyroiditis. Since identifying the first clinical signs of this condition is particularly difficult, it is advisable to perform annual blood tests to monitor thyroid hormone levels, especially TSH, FT3, and FT4.

Celiac Disease

Celiac disease is an autoimmune disorder caused by the body’s reaction to foods containing gluten, a protein found in wheat, barley, and rye, as well as in oats, spelt, kamut, and triticale. In individuals affected by celiac disease, gluten intake triggers an immune response in the small intestine, a reaction that over time causes inflammation which damages the lining of the small intestine, preventing the absorption of certain nutrients.

The damage caused in the intestine may result in weight loss, bloating, and in some cases diarrhea. Other organs that may be damaged due to this condition include the brain, nervous system, and liver, which may be deprived of vital nourishment.

Type 1 Diabetes

Type 1 diabetes is a form of diabetes that was previously referred to as “juvenile diabetes,” since it mainly occurs during childhood and adolescence. Nevertheless, cases developing in adulthood are not uncommon.

Type 1 diabetes, also called diabetes mellitus, is an autoimmune disease because it is caused by the production of autoantibodies that attack beta cells, which are responsible for insulin production within the pancreas.

The consequence of this autoimmune attack is a reduction in insulin, whose specific role is to regulate the use of glucose by the cells. This causes an excess of glucose in the bloodstream, a condition identified as hyperglycemia.

When insulin is lacking, the body is unable to use the sugars consumed through food, which are therefore eliminated through urine. The body is thus forced to produce energy in other ways, specifically through fat metabolism, a mechanism that leads to the production of so-called ketone bodies. The accumulation of ketone bodies in the body, if not treated promptly, can have very dangerous consequences up to and including coma.

Atrophic Gastritis

Autoimmune metaplastic atrophic gastritis is an autoimmune disease that affects the parietal cells of the gastric wall, causing hypochlorhydria and reduced production of intrinsic factor, a glycoprotein synthesized by the parietal cells of the gastric mucosa. The most significant consequences of this condition are vitamin B12 malabsorption and, in many cases, the development of pernicious anemia.

Is Psoriasis a Disease Associated with Vitiligo?

Over the years, much has been said about the relationship between vitiligo and psoriasis, with the latter long being incorrectly considered a condition associated with vitiligo. A fundamental contribution helped clarify the subject, thanks to an article that definitively excludes the comorbidity relationship between the two disorders.

The article, published in 2012 in the Journal of Cutaneous Medicine and Surgery by Michael Sawchuk, Frank Spano, and Wei Jing Loo, aimed to conduct an in-depth analysis of scientific literature to determine whether cases of psoriasis among individuals affected by vitiligo were more numerous than expected, and vice versa. The analysis used the three most important journals in the field and examined all English-language articles published between 1968 and 2010 dedicated to the coexistence of vitiligo and psoriasis.

Among the 338 articles examined, the prevalence of psoriasis among patients affected by vitiligo, and vice versa, did not significantly differ from that observed in the baseline population studied.

In conclusion, the 2012 study did not demonstrate the expected increase in psoriasis prevalence among people with vitiligo, or vice versa, instead suggesting that the coexistence of the two conditions is due to chance. “To conclusively demonstrate that psoriasis is more common in people with vitiligo and vice versa,” the article abstract concludes, “large epidemiological studies are necessary.”

Although vitiligo and psoriasis may be considered fairly similar conditions from a certain perspective, examining their associated increased risks reveals clear differences. “Increased risk” refers to the greater probability of developing another disease that characterizes individuals affected by a certain condition. For example, psoriasis carries an increased risk of melanoma, various epithelial cancers, lymphomas, hypertension, metabolic diseases such as diabetes, and heart disease — risks that vitiligo does not present. In fact, in some cases, such as melanoma or epithelial cancers, the risk is significantly reduced in vitiligo patients. Individuals affected by vitiligo instead have an increased risk of developing thyroid dysfunctions, atopic dermatitis, celiac disease, type 1 diabetes, atrophic gastritis, and alopecia areata.

Ultimately, the presence of vitiligo and psoriasis together would appear to be simply linked to a statistical fact: we must remember that we are talking about one disease affecting 4–5% of the population (psoriasis) and another affecting about 1%, so there are obviously many individuals affected by both conditions.