Pityriasis rosea is a common skin disease. Its cause is not yet clear. In the past, there were various theories such as infection (fungi, bacteria), lesions, allergies, metabolic disorders, etc., but none of them have been confirmed. Although there are reports of the same patient in the family, there is no obvious relationship with heredity or race. The onset process, seasonal effects, and rare recurrence of this disease all suggest that this disease may be related to some infectious factor. Currently, it is tended to be viral infection. It was once thought that it was caused by picornavirus, and others thought that it was caused by picornavirus. Those with systemic immune diseases need further research to confirm.

Clinical manifestations

The reason why this disease is called pityriasis rosea is because its rash is rose red, slightly higher than the skin, and some are contained in the skin and vary in size. , some are as big as small buttons, some are as big as coins, oval in shape, covered with a thin layer of bran-like skin, called bran-like scales.

Pityriasis rosea tends to occur in spring and autumn. It is more common in young and middle-aged people, slightly more in women than men. The onset of the disease initially occurs when a round light red spot appears on the trunk, which is called the "mother spot" ". The female spot continues to expand, even reaching the size of an egg. Afterwards, relatively small erythema gradually appears on the trunk, and often spreads to the neck and proximal limbs, but generally does not occur on the face and calves. The rash appears in batches, so rose, yellow-red, yellow-brown, and light brown rashes can be seen on the patient at the same time. Most of these rashes are oval in shape, with their long axis consistent with the texture of the skin.

Generally, patients are asymptomatic, and some feel itchy consciously, with varying degrees of itching. Individual patients have systemic symptoms such as low fever, headache, general malaise, sore throat, joint pain or swollen lymph nodes.

Pityriasis rosea is also called "wind-heat sore" in traditional Chinese medicine. It is caused by the evil of exogenous wind-heat, which stagnates the muscles, the hair orifices are blocked, the yang energy is blocked, and the accumulation produces heat and blood. Heat transforms into dryness, injuring the Yin fluid and spreading to the skin. Aiming at the cause of "external attack of wind-heat and blood-heat transforming into dryness", the treatment should be to dispel wind, clear away heat, cool blood and moisturize dryness. While taking the medicine, you should avoid scratching the affected area and avoid eating spicy, greasy food and fishy things that cause wind.

Diagnosis and differential diagnosis

It is not difficult to diagnose based on the rash shape, predilection site, arrangement, self-limiting nature, and generally no recurrence. But sometimes it needs to be differentiated from the following diseases.

(1) Tinea corporis: The scope of damage is mostly limited and generalized cases are generally less common. There are papules or small blisters on the edges. Fungal test positive.

(2) Tinea versicolor: The rash shape and location are sometimes similar to pityriasis rosea, but the fungal test is positive.

(3) Psoriasis: The rash is mostly distributed on the extended sides of the limbs and elbows and knees. There are silvery white scales. When the scales are scraped off, spot-like bleeding can be seen. It is often aggravated in winter, has a long course, and is easy to relapse.

(4) Seborrheic dermatitis is more common on the scalp and face, with greasy scales. The rash is located on the trunk and has no particular arrangement.