Lichen planus on the lip – reticulate/net-like pattern of lacy white hyperkeratosis.
圖示咀唇扁平苔蘚- 網狀型
40~60%苔蘚斑塊患者口咽受累. 這是典型的網狀型苔蘚斑, 頰粘膜、唇及其他部位粘膜乳白色角化過度. 另一類型苔蘚斑為糜爛型/潰瘍型,並未顯示於此圖.
40-60% of the patients with lichen planus have oropharyngeal involvement. This is a typical case of reticular lichen planus. Reticulate (net-like) pattern of lacy white hyperkeratosis on buccal mucosa, lips and other parts of the mucus membrane. The other type is erosive/ulcerative lichen planus which is not shown in the photo.
flat-topped, polygonal, sharply defined, violaceous papules. Surface is shiny with fine white lines (Wickham striae).
圖示威克姆氏紋(丘疹上的網)
The six p’s of lichen planus – pruritic, purple, polygonal, planar, papules and peripherally located. These papules coalesce/fuse into larger hyperkeratotic plaques. Hyperkeratosis covers Wickham striae and the characteristic violaceous colour of the lesions can be seen only at the very margins.
苔癬的六個「P」特徵：瘙癢（Pruritic）、紫色（Purple）、多邊形（Polygonal）、平坦（Planar）、丘疹（Papules）、周邊分佈（Peripherally located）。
這些丘疹會逐漸融合成較大的角化性斑塊。角化過度覆蓋了 Wickham 紋（白色細紋），而病灶特有的紫羅蘭色僅能在斑塊邊緣清楚顯示。
According to textbook, there is a predilection for flexural aspects of arms and legs. However, in this patient, the involved areas are on the extensor aspects of the limbs. 按教科書的說法,扁平苔蘚好發於四肢的屈側,而本例則發生於肢體的伸側.
扁平苔蘚：臨床概述與病理機制
疾病特徵
扁平苔蘚是一種慢性炎症性皮膚病，典型表現為紫紅色、多邊形、界限清楚的丘疹或斑塊，常伴劇烈瘙癢。好發部位包括四肢屈側、手腕內側，以及口腔與生殖器黏膜。雖然任何年齡、性別、種族均可罹患，但最常見於中壯年人群。流行病學調查顯示，在美國皮膚科門診患者中，約有 1% 為扁平苔蘚病例。
病理機制
目前認為扁平苔蘚源於細胞免疫反應異常。病灶皮膚切片可見表皮與真皮交界處淋巴球浸潤，形成典型苔蘚樣炎症反應。研究指出，淋巴球攻擊表皮基底細胞，導致細胞激素分泌並吸引更多炎症細胞。此病被視為自體免疫疾病之一，常與紅斑性狼瘡、皮肌炎、硬皮症、原發性膽管硬化症、潰瘍性大腸炎、重症肌無力等疾病並存。部分患者亦伴隨圓禿或白斑。
臨床表現
- 皮膚病灶：大小不一，從米粒至手掌大小，呈紫紅色丘疹或斑塊，表面可見白色細紋（Wickham striae）。
- 瘙癢：皮膚病灶多伴劇烈瘙癢；口腔或生殖器黏膜病灶則以灼熱或疼痛為主。
- Koebner 現象：外傷或搔抓可誘發新病灶，呈線狀排列。
- 指甲與毛髮：部分患者出現甲板變薄、縱向凹槽、甲背翼狀胬肉；頭皮病灶可導致瘢痕性落髮。
臨床亞型
- 口腔型：女性多見，頰黏膜、舌頭、牙齦出現白色網狀斑塊，常伴灼熱或潰瘍。
- 生殖器型：男性常見於龜頭，女性則表現為外陰白色網狀丘疹或潰瘍。
- 肥厚型：好發於小腿，病灶粗厚、鱗屑明顯，瘙癢劇烈。
- 萎縮型：呈紫紅色斑，鱗屑不明顯。
- 潰瘍型：黏膜病灶伴潰瘍，症狀顯著。
- 毛囊型：又稱 lichen planopilaris，導致瘢痕性落髮。
- 水疱型：下肢常見，伴其他典型病灶。
- 日光型：非洲或印度人常見，病灶位於日曬部位。
- 色素型：深膚色人種常見，病灶呈深咖啡色斑。
病程與預後
扁平苔蘚病程可持續數月至數年。約 85% 患者在 18 個月內緩解，但口腔型病程可長達 5–20 年。潰瘍性口腔扁平苔蘚有罹患鱗狀細胞癌的風險，尤其在吸菸或酗酒患者中更高。
治療原則
- 第一線：強效局部類固醇藥膏（如 clobetasol、betamethasone），每日 2 次，連續使用數月。黏膜病灶可用專用口內膏或粉末狀噴劑。
- 第二線：口服或注射類固醇、紫外線光療、維生素 A 酸、免疫抑制劑（如 cyclosporine）。
- 局部免疫抑制劑：Tacrolimus 或 pimecrolimus 藥膏可抑制 T 細胞活化，對黏膜病灶特別有效。
- 輔助治療：抗組織胺止癢，避免搔抓；生活作息規律，減少壓力，避免刺激性食物。
結論
扁平苔蘚是一種慢性自體免疫性皮膚病，臨床表現多樣，病程漫長但多數患者預後良好。治療以局部類固醇為主，必要時輔以免疫抑制劑或光療。由於部分亞型存在惡變風險，尤其是潰瘍性口腔扁平苔蘚，需醫生長期追蹤。
Lichen Planus: Clinical Overview and Pathogenesis
Characteristics
Lichen planus is a chronic inflammatory skin disease. Its hallmark is pruritic, violaceous, polygonal papules or plaques with well‑defined borders. Common sites include flexural surfaces of the limbs, the inner wrists, as well as oral and genital mucosa. Although it can occur in any age, sex, or race, it most frequently affects middle‑aged adults. Epidemiological studies suggest that about 1% of dermatology outpatients in the United States are diagnosed with lichen planus.
Pathogenesis
The condition is thought to result from abnormal cell‑mediated immune responses. Histopathology shows dense lymphocytic infiltration at the dermo‑epidermal junction, producing the characteristic lichenoid reaction. Lymphocytes attack basal keratinocytes, triggering cytokine release and attracting further inflammatory cells. Lichen planus is considered an autoimmune disease, often associated with dermatomyositis, systemic lupus erythematosus, scleroderma, primary biliary cirrhosis, ulcerative colitis, and myasthenia gravis. Other immune‑related skin disorders such as alopecia areata and vitiligo have also been linked.
Clinical Features
- Skin lesions: Variable in size (from millet‑sized papules to palm‑sized plaques), polygonal, violaceous, sometimes coalescing. Fine whitish streaks (Wickham striae) may be visible.
- Pruritus: Intense itching is a major feature. Oral or genital lesions, however, present with burning or pain rather than itch.
- Koebner phenomenon: New lesions may appear along scratch marks or trauma sites.
- Nails and hair: Nail thinning, longitudinal ridging, dorsal pterygium; scalp lesions may lead to scarring alopecia.
Clinical Variants
- Oral lichen planus: More common in women; white reticular patches on buccal mucosa, tongue, gingiva, or lips, sometimes ulcerated. Symptoms include burning, sensitivity to hot or spicy foods, and pain.
- Genital lichen planus: In men, violaceous or erythematous plaques on the glans; in women, reticular white papules or erosions on the vulva.
- Hypertrophic type: Chronic, thickened plaques with heavy scaling, usually on the shins or ankles; intensely pruritic.
- Atrophic type: Thin violaceous patches with little scaling.
- Erosive type: Ulcerated lesions on oral or genital mucosa.
- Follicular type (lichen planopilaris): Keratotic papules around hair follicles, leading to scarring alopecia.
- Bullous type: Vesicles or bullae, often on the lower limbs.
- Actinic type: Seen in darker‑skinned populations, lesions on sun‑exposed areas.
- Pigmented type: Dark brown macules, more common in darker skin tones.
Course and Prognosis
The disease may last months to years. About 85% of patients achieve remission within 18 months, but oral lichen planus can persist for over 5–20 years. Erosive oral lesions carry a small risk of malignant transformation, especially in smokers or heavy drinkers, necessitating close monitoring.
Treatment Principles
- First‑line: Potent topical corticosteroids (e.g., clobetasol, betamethasone), applied twice daily for several months. Mucosal lesions may require specialized formulations.
- Second‑line: Systemic corticosteroids, phototherapy, retinoids, or immunosuppressants (e.g., cyclosporine).
- Topical immunomodulators: Tacrolimus or pimecrolimus ointments can suppress T‑cell activation, particularly effective for mucosal lesions.
- Supportive care: Antihistamines for itch, avoidance of trauma, stress reduction, and dietary modifications (avoiding spicy or hard foods for oral lesions).
Conclusion
Lichen planus is a chronic autoimmune skin disorder with diverse clinical variants. While most patients eventually improve, relapses are common and treatment may extend for years. Oral erosive lichen planus requires vigilant follow‑up due to its potential for malignant transformation. Patient education, lifestyle management, and long‑term dermatologic care are essential for optimal outcomes.