🩺 醫學討論：接觸性皮炎與帶狀皰疹的鑑別
病例簡介
一位女士因腳背出現細小水泡、痕癢及紅腫而求診。值得注意的是，紅腫範圍呈正方形。
臨床問題
- 可能診斷：
- 接觸性皮炎
- 帶狀皰疹（俗稱「生蛇」）
討論
皮膚出現水泡、紅腫及痕癢的常見原因包括接觸性皮炎與帶狀皰疹。兩者在臨床表現上有一定相似之處，但仍有關鍵差異：
- 接觸性皮炎：通常以痕癢為主，病灶形狀與接觸源密切相關。若皮膚接觸到致敏物質（如藥酒、膏布），便會在相應區域出現紅腫、水泡。
- 帶狀皰疹：由水痘‑帶狀皰疹病毒再活化引起，常見於單側皮節分佈。主要症狀是疼痛，而非痕癢，並伴隨成簇水泡。
在本病例中，仔細觀察可見患處及腳趾附近有黃色染料痕跡。經詳細詢問，病人透露數日前因腳掌扭傷而求診鐵打，並使用藥酒敷貼。其皮膚對藥酒成分產生過敏反應，導致水泡、紅腫及痕癢。由於膏布形狀為正方形，紅腫範圍亦呈正方形，進一步支持接觸性皮炎的診斷。
最終診斷
- 敏感性接觸性皮炎
治療建議
- 中至強度外用類固醇藥膏：減輕炎症反應
- 口服抗組織胺：緩解痕癢
- 嚴重病例：可能需要短期口服類固醇
結論
本病例顯示，皮膚病灶的形狀與接觸源之間的關聯是診斷接觸性皮炎的重要線索。與帶狀皰疹相比，接觸性皮炎以痕癢為主，且病灶分佈符合接觸物的形狀。透過詳細病史詢問及臨床觀察，能有效區分兩者並給予適切治療。值得一提的是，有時候接觸性皮炎與帶狀皰疹一齊出現，問題會更加複雜。
🩺 Discussion: Differentiating Contact Dermatitis and Herpes Zoster
Case Summary
A woman presented with small blisters, itching, and redness on the dorsum of her foot. Notably, the area of redness was square‑shaped.
Clinical Question
- Possible diagnoses:
- Contact dermatitis
- Herpes zoster (“shingles”)
Discussion
Skin lesions with blisters, redness, and itching are commonly seen in both contact dermatitis and herpes zoster. While they may appear similar, there are important differences:
- Contact dermatitis: Typically characterized by itching. The shape and distribution of the lesion often correspond to the area of contact with the irritant or allergen. For example, exposure to medicated wine or plasters can cause localized redness and blistering.
- Herpes zoster: Caused by reactivation of the varicella‑zoster virus, usually affecting one side of the body along a dermatome. Pain is the predominant symptom rather than itching, and lesions appear as clusters of blisters.
In this case, careful observation revealed yellow dye around the toes and affected area. On further questioning, the patient reported that she had sprained her foot a few days earlier and sought treatment from a traditional bone‑setter, who applied medicated wine and plasters. The patient’s skin reacted to the ingredients in the medicated wine, leading to blisters, redness, and itching. Because the plaster was square‑shaped, the area of redness also appeared square, supporting the diagnosis of contact dermatitis.
Final Diagnosis
- Allergic contact dermatitis
Treatment Recommendations
- Medium to high potency topical corticosteroid cream to reduce inflammation
- Oral antihistamines to relieve itching
- Severe cases: Short course of oral corticosteroids may be required
Conclusion
This case highlights that the shape of a skin lesion can provide important clues to its cause. Unlike herpes zoster, which is painful and follows a dermatomal distribution, contact dermatitis is primarily itchy and corresponds to the area of exposure. Careful history‑taking and clinical observation are essential to distinguish between the two conditions and to provide appropriate treatment. It is worth noting that sometimes contact dermatitis and herpes zoster can occur together, which makes the problem even more complicated.