Epidemiology

Polymorphic light eruption is also known as sun allergy, sun poisoning, sunlight eczema, or summertime itch/rash.

• Age: Commonly found in young people aged 20-40.
• Gender: Women have a four times higher prevalence than men.
• Geography: Common in temperate climates, areas with little sunshine, or regions at high altitudes compared to sea level.
• Skin Type: Occurs in all races but is most common in individuals with Fitzpatrick skin type I.

Causes and Pathogenesis

The core mechanism of PMLE is a delayed hypersensitivity reaction. Key influencing factors include:

• Ultraviolet rays: UVA rays are the main cause (accounting for 75-90%), capable of penetrating window glass. UVB rays or a combination of both can also cause the condition.
• Immune disorders: In normal individuals, UV rays suppress local immunity to protect the skin. In PMLE patients, this mechanism is impaired, leading to increased inflammation with the presence of T lymphocytes (CD4 and CD8).
• Hormonal factors: Estradiol in women is believed to inhibit the natural UV-induced immune suppression, explaining the higher susceptibility in females.
• Genetics: About 15-46% of cases have a family history.

Clinical Manifestations

The condition often flares in spring and early summer, appearing after sun exposure from a few hours up to 2 days, and subsides or completely disappears in winter. However, there are cases of flaring in winter when patients are exposed to intense sunlight such as sunbathing or traveling to geographic areas with higher light intensity.

Lesion morphology: Although termed “polymorphic,” in a specific patient, the lesion morphology tends to be consistent across episodes, including:

• Papules, vesicles, or eczema-like red patches.
• Wheal-like or target-like lesions (resembling erythema multiforme).
• Lesions will worsen if the skin area continues to be exposed to sunlight.
• Papules and skin lesions can completely heal without scarring.

Location: Symmetrical on exposed skin areas (arms, legs, neck, chest). Less common on the face and the backs of hands due to the “skin hardening” effect.

Symptoms: Intense itching is a main manifestation. Sometimes accompanied by fever, headache, or nausea.

Skin hardening effect: With prolonged sun exposure, the skin adapts by increasing melanin and thickening the stratum corneum, helping symptoms gradually lessen by the end of summer.

Diagnosis

Diagnosis primarily relies on history taking and clinical examination.

Paraclinical: Skin biopsy (non-specific, mainly showing spongiosis and lympho infiltrates). Severe cases may exhibit papillary edema. Antinuclear antibody (ANA) testing to exclude Lupus.

Phototesting: Light stimulation tests can be performed to confirm the diagnosis (positive in about 60% of patients).

Differential diagnosis: Should be differentiated from Lupus erythematosus, Porphyria, solar urticaria, and contact photodermatitis.

Treatment

Preventive measures

• Use broad-spectrum sunscreen (SPF 50+, against both UVA/UVB).
• Wear protective clothing, avoid going out in peak sunlight hours.
• Choose areas with soft light, shade if having to be outdoors.
• Limit sitting near windows, especially glass windows, when indoors.

Specific treatment

• Topical: Topical corticosteroids or Calcipotriol.
• Systemic: Short-term oral corticosteroids (1-2 weeks) for acute flare-ups. Hydroxychloroquine or Nicotinamide (used before flare-up seasons).
• Phototherapy: Low-dose UVB or UVA exposure at the beginning of spring for gradual skin adaptation (causing tolerance).
• Severe cases: Azathioprine or Ciclosporin can be considered.

About 60% of patients improve or recover after 15 years, 75% improve or recover after 30 years, but PMLE can persist for life.

While PMLE does not pose a life-threatening risk and has a benign prognosis, it significantly impacts the quality of life and psychological well-being of patients due to its persistent, recurrent nature. By combining physical protective measures, “skin hardening” therapy through phototherapy, and reasonable medication use, patients can effectively manage symptoms. Over time, with the natural adaptation of the immune system, the impact of PMLE will gradually subside, restoring confidence in outdoor activities.

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Epidemiology

Polymorphic light eruption is also known as sun allergy, sun poisoning, sun eczema, or summer pruritus rash/swellings.

• Age: Common in young people aged 20 – 40 years.
• Gender: Women have a 4 times higher incidence rate than men.
• Geographical region: Common in temperate climates, areas with less sunlight, or high-altitude regions.
• Skin type: Occurs in all races but is most common in individuals with Fitzpatrick skin type I.

Causes and pathogenesis

The core mechanism of PMLE is a delayed hypersensitivity reaction. Some major contributing factors include:

• Ultraviolet rays: UVA is the main agent (accounting for 75 – 90%) and can penetrate through window glass. UVB or a combination of both can also cause the condition.
• Immune system disorder: In normal individuals, UV rays locally suppress the immune system to protect the skin. In PMLE patients, this mechanism is impaired, leading to increased inflammation with the presence of T lymphocytes (CD4 and CD8).
• Endocrine factors: Estradiol in women is believed to block the natural immunosuppressive effect of UV rays, explaining why women are more prone to the condition.
• Genetics: About 15 – 46% of cases have a family history.

Clinical manifestations

The condition usually flares up in spring and early summer, appearing after sun exposure from a few hours to 2 days and subsiding or disappearing completely in winter. However, it can also flare up in winter when the patient is exposed to strong sunlight such as sunbathing or travelling to areas with higher light intensity.

Lesion morphology: Although termed “polymorphic,” in a specific patient, lesion morphology remains consistent across episodes, including:

• Papules, blisters, or eczema-like red patches.
• Urticarial or target-like lesions (similar to erythema multiforme).
• Lesions will continue to worsen if the area is still exposed to sunlight.
• Papules and skin lesions can heal completely without scarring.

Location: Symmetrical on exposed skin areas (arms, legs, V-neck, chest). Less common on the face and back of the hands due to the “skin hardening” effect.

Symptoms: Intense itching is the main symptom. Sometimes accompanied by fever, headache, or nausea.

Skin hardening effect: With prolonged sun exposure, the skin adapts by increasing melanin and thickening the stratum corneum, helping symptoms gradually decrease by the end of summer.

Diagnosis

Diagnosis is primarily based on medical history and clinical assessment.

Laboratory tests: Skin biopsy (nonspecific, mainly showing spongiosis and lymphocytic infiltration). Severe cases may show dermal papillary edema. Antinuclear antibody (ANA) test to rule out Lupus.

Phototesting: Light stimulation test can be performed to confirm the diagnosis (positive in about 60% of patients).

Differential diagnosis: Needs to be differentiated from Lupus erythematosus, Porphyria, solar urticaria, and allergic contact dermatitis to light.

Treatment

Preventive measures

• Use broad-spectrum sunscreen (SPF 50+, against both UVA/UVB).
• Wear protective clothing, avoid going out during peak sunlight hours.
• Choose areas with soft light and shade if needing to be outdoors.
• Limit sitting near windows, especially glass windows.

Specific treatments

• Topical: Apply corticosteroids or Calcipotriol.
• Systemic: Short-term oral corticosteroids (1-2 weeks) during acute episodes. Hydroxychloroquine or Nicotinamide (used before flare-up season).
• Phototherapy: Low-dose UVB or UVA exposure at the start of spring to gradually acclimate the skin (causing desensitization).
• In severe cases: Consider Azathioprine or Cyclosporine.

About 60% of patients improve or recover after 15 years, 75% see reduction or recovery after 30 years, although PMLE can last a lifetime.

PMLE though not life-threatening and with a benign prognosis, significantly affects the quality of life and psychology of patients due to its persistent recurrence. By combining physical protection measures, “skin hardening” therapy through phototherapy, and appropriate medication use, patients can effectively manage symptoms. Over time, along with the natural adaptation of the immune system, the effects of PMLE will gradually diminish, providing confidence to patients in outdoor activities.

Bài viết Polymorphic Light Eruption đã xuất hiện đầu tiên vào ngày DUPOMA Global.

Operation of Bodily Fluids in the Body

Only when the metabolism of bodily fluids is balanced can normal life activities occur. Once imbalanced, it leads to “water” diseases.

When we drink water, how are the bodily fluids metabolized and circulated in the body? Normally, bodily fluids circulate in the form of “qi” (steam or vapor). This means water must transform from a liquid state into a gaseous (qi) state to circulate throughout the body. To transform water into qi, a driving force is needed — that is, fire. Fire in human physiology is yang qi. The warming and transforming actions of yang qi promote the conversion of bodily fluids into qi, similar to boiling water to produce steam — requiring fire. In Chinese medicine, this process is called “qi transformation”.

If there is a deficiency in yang qi, bodily fluids cannot transform into qi and will accumulate somewhere: under the skin causing edema, in the chest or abdomen causing hydrothorax or ascites, or accumulate in organs leading to water disorders of the five organs (five organ water diseases). Therefore, water-related diseases are largely due to a deficiency in yang qi or lack of “fire”. Hence, when treating, warm yang herbs are often added to promote the transformation of water into qi. Just as Zhang Zhongjing stated, “For phlegm and fluid ailments, one should use warm medicine to harmonize” (For phlegm and fluid ailments, warm medicine should harmonize).

Some Disorders Due to Fluid Metabolism Imbalance

When the body’s fluid metabolism becomes chaotic, various signs will appear, including those caused by water, dampness, phlegm, and fluid, leading to issues across all systems.

The proliferation of water, dampness, phlegm, and fluid collectively refers to fluid metabolism disorders. Generally: dampness accumulates into water, water gathers into fluid, fluid accumulates into phlegm. The more liquid form is fluid, and the thicker form is phlegm. Clinically, it can sometimes be difficult to clearly differentiate, resulting in terms like: water-dampness, water-fluid, phlegm-fluid, phlegm-dampness, representing the holistic perspective of Chinese medicine.

Treatment of Water Disorders in 《伤寒论 – Treatise on Cold Damage》

The treatment of water disorders in 《伤寒论 – Treatise on Cold Damage》is clearly stratified into three basic levels: Transforming water (fluid), facilitating water, and expelling water.

• Transforming water: When water and dampness have not yet become severe, the method of warming yang to transform qi is used (using warm yang herbs or aromatic herbs to evaporate water and dampness). This is like a light rain moistening the ground, which evaporates when the sun appears. Formulas like Fu Ling Gan Cao Tang and Ling Gui Gan Zao Tang belong to this category.
• Drying dampness/Permeating dampness: When water accumulation increases (like a small pond), simply warming isn’t fast enough. At this stage, “Drying dampness” (using drying herbs) or “Permeating dampness” (using soil to cover the pond so water is absorbed into the ground) is required. The Spleen is associated with Earth, so tonifying the Spleen essentially equates to enhancing Earth to permeate dampness. Formulas like Ling Gui Zhu Gan Decoction and Li Zhong Decoction belong to this category.
• Facilitating water: If water and dampness are excessive (like a large pond), using soil to cover is labor-intensive. The best method is to clear the water flow (dig drainage). This is the facilitating water method. Formulas like Wu Ling San, Zhen Wu Tang, and Zhu Ling Tang fall into this group.
• Expelling water: If water and dampness are extremely severe, akin to flooding or severe blockage, a strong method to expel the flood is necessary. This is the expelling water method (strong purging, both urination and defecation increase significantly). Special care is needed when using this approach. Formulas like Shi Zao Tang, Da Xian Xiong Tang, and Mu Li Zhe Xie San are in this group.

Ling Gui Zhu Gan Decoction – Composition and Uses

Ling Gui Zhu Gan Decoction comprises four ingredients: Fu Ling, Gui Zhi, Bai Zhu, Gan Cao. This blend incorporates damp-drying, permeating, and facilitating water.

• Fu Ling: Tasteless and mildly balanced, it permeates dampness and facilitates urination to eliminate excess water, also tonifying the Spleen and calming the heart.
• Gui Zhi: Pungent and sweet with a warm nature, it warms yang to transform qi, opens appetite, strengthens the Spleen, and dilates blood vessels to “transform” excess water.
• Bai Zhu: Bitter and warm, it tonifies and benefits Spleen qi, dries dampness, and works with Fu Ling to absorb residual water fluids.
• Gan Cao: It nourishes Spleen qi on one hand, and harmonizes the other ingredients on the other.

Ling Gui Zhu Gan Decoction Treats Dizziness

Zhang Zhongjing uses it to treat internal fluid retention syndrome due to Spleen deficiency. The Spleen is “the source of qi and blood” and “the acquired root.” When the Spleen is deficient it fails to transport and transform fluids, causing water which turns to phlegm and dampness resulting in illness.

In 《伤寒论 – Treatise on Cold Damage》, Spleen deficiency with water retention can lead to: “the region under the heart is irritated and full, qi rushes up to the chest, standing causes dizziness… the body trembles unsteadily” (the area below the heart is bloated, qi surges to the chest, standing causes dizziness… the body trembles unsteadily). Ling Gui Zhu Gan Decoction is a “trump card” for treating dizziness caused by mid-focus fluid dampness invading the head.

Ling Gui Zhu Gan Decoction Treats “Water-Heart Disease”

The renowned master Liu Douzhou used this formula marvelously to treat heart diseases due to water rising to the heart, coining the term “water-heart disease”.

• Observing color: Dark facial color (water color). In severe cases, black spots may appear on the cheeks, nose, lips (water spots).
• Tongue diagnosis: Pale and swollen tongue, with a slick and wet coating.
• Pulse diagnosis: Wiry, deep or knotted pulse.
• Differential diagnosis: Symptoms of water qi surging upward (qi surging from below the heart to the throat); chest pain and fullness; palpitations; shortness of breath.

Ling Gui Zhu Gan Decoction for Water Qi and Phlegm-Fluid

With their flowing nature, water qi and phlegm-fluid cause diverse diseases in the cardiovascular, digestive, respiratory, and sensory systems.

• “Strange” heart diseases: A coronary artery disease patient frequently spat white foam from the throat up to 1 meter, accompanied by nausea and hand tremors. Liu Lao diagnosed water qi rising to the heart, using Ling Gui Zhu Gan Decoction combined with Ze Xie, Ban Xia, and fresh ginger, cured in 14 doses.
• Digestive: Bloating, loss of appetite, nausea, immediate bowel urge after eating. This formula strongly nourishes central qi, helping boost immunity.
• Respiratory: Coughing or wheezing due to phlegm-fluid, with copious phlegm. This formula treats the underlying cause of phlegm by strengthening the Spleen.
• Sensory: Used for papilledema (can be combined with Ren Shen, Ju Hua, Gou Qi Zi, Che Qian Zi), increased intraocular pressure, allergic rhinitis, postnasal drip (combined with Li Zhong Tang).

Modifications to Ling Gui Zhu Gan Decoction

Clinical modifications can be made according to symptoms:

• Excessive phlegm with slippery pulse: Combine with Er Chen Tang.
• Severe dizziness: Add Ze Xie.
• Facial flushing: Add Bai Wei.
• High blood pressure: Add Hong Hua, Xi Xian Cao, Yi Mu Cao, Niu Xi.
• Knotted or large pulse: Remove Bai Zhu and add Wu Wei Zi.
• Cold damp-induced cough: Remove Bai Zhu and add Yi Yi Ren.
• Palpitations or fearfulness: Add Long Gu, Mu Li.

With its ability to strengthen the Spleen and harmonize the center, Ling Gui Zhu Gan Decoction is the optimal solution for disorders caused by water qi and phlegm-fluid. The flexible application of transforming-facilitating-expelling water levels helps achieve high clinical efficacy.

Bài viết Ling Gui Zhu Gan Decoction – A formula for treating “water” symptoms in the Treatise on Cold Damage. đã xuất hiện đầu tiên vào ngày DUPOMA Global.