錢幣狀濕疹

Nummular Eczema

錢幣狀濕疹的特徵是邊緣清晰的橢圓形紅斑性濕疹斑塊，主要發生部位是四肢伸側，尤其是小腿，但也可能發生在手指或身體軀幹，臨床上少見於臉部和頭皮。罹病率約為每千人約有2例。急性期可見到乾燥、增厚、龜裂等慢性濕疹樣變化；細菌感染常因搔抓而發生，呈化膿或黃色結痂等膿皰疹樣的表現。通常病變的大小直徑從1–10公分不等。但是如果懷疑是黴菌感染，則應該對皮膚刮屑進行氫氧化鉀（KOH）的檢查；由於接觸性導致的皮膚過敏在錢幣狀濕疹中很常見到，因此慢性頑固性的錢幣狀濕疹患者應考慮進行貼膚試驗，避免誘發因素、良好的皮膚照護和強效的外用類固醇是治療的主要方式；病灶多半呈多發性，對稱分佈。好發部位在下肢，其次是手臂；臨床診斷主要基於瀰漫性皮膚乾燥的患者，皮膚特徵呈圓形至橢圓形的紅斑；錢幣狀濕疹臨床上應與其他圓形的皮膚病變區分，病變最初徵狀是丘疹或小水泡，然後逐漸合併成斑塊狀。

Nummular eczema is characterized by sharply defined, oval or coin-shaped, erythematous, eczematous plaques. The predominant site is the extensor side of the extremities, especially on the calves. The lesions can also occur on the fingers and the trunk, but they are rarely seen on the face and scalp. Clinically, it has a prevalence of about 2 cases per 1,000 people. In the acute stage, dry, thickened, cracked, and other chronic eczema changes can be observed. Bacterial infection often occurs due to scratching, manifesting a pus, yellow crusts, and other pustular rash-like manifestations. Typically, the size of the lesion varies from one to 10 cm in diameter. However, a potassium hydroxide (KOH) wet-mount examination of skin scrapings should be performed if tinea corporis is suspected. Due to the commonality of contact allergy with nummular eczema, patch testing should be considered in patients with chronic, recalcitrant nummular eczema. Avoidance of precipitating factors, optimal skin care, and high-potency topical corticosteroids constitute the mainstay of therapy. The lesions are usually multiple and symmetrically distributed, with predilection sites on the lower limbs followed by the upper limbs. The diagnosis is mainly clinical based on the characteristic round to oval erythematous plaques in a patient with diffusely dry skin. Nummular eczema should be differentiated from other annular lesions, as the lesions are initially papules or small blisters and then merge into plaques.