What is Pityriasis Rotunda?
Pityriasis rotunda is a less common skin condition linked to a disorder that affects skin cell production, first identified in 1906. Originally given other names, this condition is known for its distinct signs on the skin. These include areas of skin that are darker or lighter than the surrounding skin, with very clear borders that are round or oval in shape. These patchy changes are usually found on the body and near parts of the arms and legs that are closer to the body. While this condition is not frequently seen in certain parts of the world, it can sometimes be hard to diagnose.
What Causes Pityriasis Rotunda?
Pityriasis rotunda is a skin condition, but we don’t exactly know what causes it. Some experts think it might be related to certain skin disorders such as ichthyosis vulgaris, late-onset congenital ichthyosis, and acquired ichthyosis, all of which affect the way skin cells are produced and die.
It’s also important to know that pityriasis rotunda might happen in relation to certain cancers. This is particularly the case with liver cancer in black patients from South Africa. But, it can also be seen with various other cancers like myeloma, multiple myeloma (cancers of a type of white blood cell), acute and chronic myeloid leukemia (kinds of blood cell cancers), prostate cancer, cancers of the esophagus and stomach, and squamous cell carcinoma of the palate (a type of mouth cancer).
There’s also some evidence to suggest that pityriasis rotunda might be linked to various other health conditions like:
– Malnutrition
– Diabetes
– Infections like tuberculosis, leprosy, and bone inflammation
– Liver conditions such as cirrhosis
– Chronic obstructive pulmonary disease and recurring lung infections
– Heart disease
– Problems with the female reproductive system like ovarian cysts and growths in the womb
– A genetic disorder that affects red blood cells called glucose-6-phosphate dehydrogenase deficiency (or favism)
– Chronic diarrhea
– Scleroderma – a disease that results in hard, tight skin
– Sarcoidosis – a disease that leads to small areas of inflammation in the body
– Hormonal disorders such as hyperprolactinemia – excessive production of a hormone called prolactin.
But remember, all these potential links are still being studied. Some links, especially with conditions like favism, could just be a coincidence.
Risk Factors and Frequency for Pityriasis Rotunda
Pityriasis rotunda is a skin condition that affects both male and female equally. However, some experts have noticed a slight tendency for females to get the condition more. Most people who get diagnosed are between the age of 20 to 45, but a person as young as 2 years old or as old as 87 years old can also get it.
Interestingly, Pityriasis rotunda is not equally common everywhere. It is particularly prevalent in Japan and among West Indian and South African black communities. It is less common among black Americans, and its frequency on the North American continent isn’t known. The condition is also rare among Caucasians, with most cases reported in Mediterranean patients, especially those from Sardinia, Italy.
There have also been reports of Pityriasis rotunda occurring within families, suggesting that it might have a genetic link and could be passed down through generations in a way scientists call ‘autosomal dominant transmission’.
Signs and Symptoms of Pityriasis Rotunda
Pityriasis rotunda is a skin condition that is typically identified through a clinical examination. These skin lesions often cause little to no symptoms. Lesions seen in this condition are round, dry, and scaly, with pronounced hair follicles, but there is no redness due to inflammation. The skin’s flakiness may be more noticeable when you scratch at the lesions. Depending on the skin color, the lesions can be less pigmented in individuals with light skin or more pigmented in those with dark skin. The patches can merge together, vary in size from 1 cm to over 20 cm, and be present anywhere from a few to a few dozens, but they rarely exceed 100.
- Round, dry, and scaly lesions with pronounced hair follicles
- No inflammatory redness
- Less pigmented in light-skinned individuals
- More pigmented in dark-skinned individuals
- Lesions can merge together
- Vary in size from 1 cm to over 20 cm
- Patches can number from a few to a few dozens but rarely exceed 100
Pityriasis rotunda mostly affects the trunk (specifically the back and abdomen), buttocks, and the upper parts of the limbs like the thighs and arms. It generally does not affect the face, hands, and feet. In some individuals, there might be accompanying skin lesions of a condition called ichthyosis vulgaris. A family history of ichthyosis vulgaris has sometimes been seen in patients with pityriasis rotunda.
A classification was proposed by Grimalt et al for pityriasis rotunda. The first type involves less than 30 dark patches, usually seen in black and Asian patients. There are often no similar cases within the family, but it can often be related to other diseases like solid tumors, infectious diseases, and systemic diseases. The second type involves more than 30 light patches, typically seen in white individuals with a family history of similar skin lesions. This type is usually not connected to an underlying disease. Although this classification is useful, there are cases where the features overlap.
The skin condition can be mistaken for other conditions like tinea versicolor, erythrasma, tinea corporis, nummular eczema, early-stage mycosis fungoides, fixed drug reaction, pityriasis rosea, pityriasis alba, figurate erythema, and leprosy.
Testing for Pityriasis Rotunda
If your skin is flaky or has lesions, your doctor may want to perform a mycological examination. This involves taking a sample of the affected skin and examining it under a microscope using a solution called potassium hydroxide. The sample may also be cultured, which means allowing any potential fungi present in the sample to grow in a controlled environment. This helps doctors to identify whether a skin fungal infection, also known as a dermatomycosis, is the cause of your symptoms.
In some cases, if a skin condition called erythrasma is suspected, a Wood light examination may be used. This involves shining a special ultraviolet light, known as a Wood’s lamp, onto the skin. If erythrasma is present, the affected skin will glow a certain color under the light, helping to confirm the diagnosis.
Treatment Options for Pityriasis Rotunda
Pityriasis rotunda is a skin condition that is often difficult to treat. There are several medications that are typically used, but they often have limited effectiveness. These treatments include topical corticosteroids (medications applied to the skin that reduce inflammation), antifungal agents (a type of medicine that kills fungal infections), emollients (moisturizers that soothe, smooth and hydrate the skin), tars (a thick, dark liquid used to treat skin conditions), and keratolytic topicals (medications that help soften and remove the outermost layer of the skin, and commonly include substances like salicylic acid and lactic acid).
In addition to these, retinoids, a type of vitamin A that encourages the skin to renew itself, have been used as well, whether as creams and gels (like retinoic acid and tazarotene) or in oral tablet forms (like etretinate). However, they too often show little to no success in treating pityriasis rotunda.
Another treatment option involves the use of vitamin D3 analogs, such as calcipotriol. These are medications that mimic the actions of vitamin D in the body and have been found to slowly improve the symptoms in a small number of patients.
However, it’s important to mention that people with other health conditions who also have pityriasis rotunda often find that treating these comorbidities successfully can in turn lead to their skin condition going into remission. This suggests that the skin condition may be linked to overall body health for some individuals.
What else can Pityriasis Rotunda be?
If you have pityriasis rotunda, which is a skin condition, doctors might need to rule out other conditions that can cause similar symptoms. These include:
- Erythrasma (a common skin infection)
- Leprosy (an infectious disease affecting the skin and nerves)
- Parapsoriasis (a group of skin disorders)
- Pityriasis alba (a common skin disorder in children)
- Pityriasis rosea (a rash that usually begins as a large spot on the chest, abdomen or back)
- Plaque psoriasis (an immune disorder that results in skin redness and irritation)
- Sarcoidosis (a disease that causes inflammation in various organs)
- Tinea corporis (ringworm of the body)
- Tinea cruris (a fungal infection of the skin in the groin)
- Tinea versicolor (a fungal infection of the skin causing light-colored patches)
