Diffuse erythema

Our skin can be said to be an effective "protective layer". But sometimes, it may be affected by fungal infection and some inflammation, causing erythema. Diffuse erythema is a common skin disease. Most of them are caused by infection after tick bites. After suffering from diffuse erythema, the skin will experience burning and itching sensation. Diffuse erythema often occurs in humid places such as forests and lakeside areas where there are many mosquitoes.

Diffuse erythema refers to the red macules or papules that appear after a tick bite. It may be an early skin manifestation of Lyme disease caused by spirochete infection. It is more common in children and young people, and is more likely to occur in forest areas. It manifests as expanding round or oval red macules that often occur on the trunk and proximal limbs. The patient feels burning and itching in the affected area, and the lesions can disappear naturally after several weeks to months.

Clinical manifestations

1. Skin manifestations

Skin lesions usually appear 7 to 15 days after the tick bite, and are prone to occur on the trunk and proximal limbs. The rash is usually a single lesion, but it can also be multiple. It starts as a round or oval red inflammatory macules that continue to expand around, with raised and infiltrated edges and a lighter color in the center. Eventually the lesions may be larger than 5 cm and occasionally appear light purple. The patient will feel burning and itching in the affected area, and the lesions will disappear naturally after several weeks to months.

2. Skin manifestations

Some patients may have involvement of the heart, nervous system, bones, joints, etc.

examine

1. Physical examination

The main examination method is visual inspection of the skin. Round or oval red macules can be seen on the trunk and limbs. The edges are raised and infiltrated, and the central area is lighter in color. Larger lesions can reach more than 5 cm.

2. Laboratory examination

Borrelia can be detected from specimens such as blood, cerebrospinal fluid and diseased skin. Specific antibodies (Lyme antibodies) can be measured in the patient's blood using immunofluorescence, immunotransfer and other methods. Pathogen isolation and specific antibody detection are of diagnostic significance.

3. Pathological examination

There is inflammatory cell infiltration around the blood vessels in the upper or middle and lower dermis. The infiltrating cells are mainly lymphocytes and histiocytes, and plasma cells and eosinophils can be seen.

diagnosis

There is a history of tick bites; the skin lesions are characterized by the occurrence of gradually expanding round or oval erythema, with the center gradually returning to normal skin color, mostly on the limbs and trunk; symptoms of involvement of the heart, joints, nervous system, etc. appear after the skin lesions; the diagnosis can be made in combination with laboratory tests that are positive for Borrelia or its specific antibodies.

Differential Diagnosis

1. Centrifugal annular erythema

It starts as a light red flat papule, which expands centrifugally into a ring shape with raised edges. After it subsides, it is replaced by pigmentation. After the disease subsides, the skin color returns to normal.

2. Erysipelas

The pathogen is hemolytic streptococcus, which manifests as a clearly defined flaky rash that is bright red and slightly raised. It fades when pressed and may cause burning pain. It is often accompanied by systemic symptoms such as headache, chills, high fever, fatigue, and loss of appetite. It can be identified through bacterial culture.

3. Cellulitis

It is a purulent inflammation of the skin, with severe local pain, diffuse redness and swelling, unclear boundaries, significant pitting edema, chills, fever and other systemic symptoms. It can be identified by bacterial culture.

treat

After the disease is diagnosed, active treatment should be given to prevent further progression of the disease. The principle of treatment is to use antibiotics in sufficient doses and for sufficient courses. It is recommended that adults and children over 8 years old take doxycycline, and children under 8 years old and pregnant women take amoxicillin; oral cefuroxime or intravenous ceftriaxone or penicillin G can also be used for treatment. During antibiotic treatment, attention should be paid to adverse reactions such as allergic reactions and gastrointestinal symptoms.