Case Report
Case History
A 35‑year‑old gentleman presented with skin lesions localized to the dorsal aspects of the finger knuckles. The lesions were non‑pruritic. The condition began over one year ago, initially as a small papule on one knuckle (exact site not recalled). He reported only minimal itching, but due to repeated picking and scratching, the papule gradually enlarged into a nodule. Subsequently, similar very mild itching developed on other knuckles, and with the same habit of scratching, additional papules enlarged into nodules.
He was advised by his family physician to avoid scratching, but the lesions persisted.
On examination, there were four well‑defined, erythematous plaques with mild scaling, excoriation, and crusting. The plaques were circular and located on the right index finger, left thumb, left index finger, and left little finger. Other knuckles appeared normal.
Feet were unremarkable. Fingernails and toenails were normal. No evidence of psoriasis, atopic eczema, or fungal infection was observed. Finger and toe web spaces were clear. Scalp, hair, and genital skin were normal.
The patient appeared calm, with no signs of anxiety or neurotic behavior.
Past medical history was negative for eczema, psoriasis, or atopic diathesis. Family history was non‑contributory.
Management
The patient was prescribed a super‑potent topical corticosteroid together with emollients for over one month. Minimal improvement was noted.
Summary
This case highlights chronic, localized, well‑defined erythematous plaques on the knuckles, resistant to high‑potency topical corticosteroids. The absence of systemic involvement, nail changes, or other dermatological signs suggests a localized dermatological condition rather than psoriasis or eczema. Further diagnostic consideration and alternative therapeutic strategies may be warranted.
病例報告
病史
患者為 35 歲男性，主訴手指關節背側出現皮膚結節，無明顯瘙癢。病情始於一年多前，最初在某一指關節出現小丘疹（患者未能確定具體位置）。雖僅有輕微瘙癢，但因反覆搔抓，小丘疹逐漸增大成為結節。隨後其他指關節亦出現輕微瘙癢，患者同樣因搔抓導致丘疹逐漸增大。
患者曾接受家庭醫生建議停止搔抓，但皮疹並未消退。
體檢顯示：共有四處界限清楚的紅斑性斑塊，伴輕度鱗屑、搔抓痕及痂皮。病灶呈圓形，分佈於右手食指、左手拇指、左手食指及左手小指的指關節背側。其他未受累的關節皮膚正常。
足部皮膚正常。手足甲均正常。未見銀屑病或異位性濕疹的其他表現。手足趾縫無異常，未見真菌感染。頭皮、毛髮及生殖器皮膚均正常。
患者精神狀態良好，無焦慮或神經質表現。
既往病史：無濕疹、銀屑病或異位性體質。家族史無特殊。
治療經過
患者接受超強效外用糖皮質激素及潤膚劑治療逾一月，僅見輕微改善。
總結
本病例特點為慢性、局限性、界限清楚的紅斑性斑塊，主要分佈於手指關節背側，對高效外用糖皮質激素反應不佳。缺乏全身性受累、甲病變或其他皮膚病徵，提示為局限性皮膚病灶，而非銀屑病或濕疹。需進一步考慮鑑別診斷及其他治療策略。
Knuckle Pads: Overview and Clinical Insights
Definition
Knuckle pads are benign, asymptomatic, well‑circumscribed, firm, skin‑colored papules, nodules, or plaques located over the dorsal aspects of the metacarpophalangeal (MCP) and interphalangeal (IP) joints. They are often associated with repetitive trauma from occupational or athletic activities.
Historical Background
Knuckle pads were first described by Garrod in 1893, though depictions date back to the Renaissance. Allison and colleagues noted their presence in Michelangelo’s sculptures, including David and Moses. The term “knuckle pad” is somewhat misleading, as lesions most commonly occur over the proximal interphalangeal (PIP) joints rather than the true knuckles.
Etiology and Pathophysiology
Knuckle pads may be:
- Idiopathic
- Genetic (familial associations with palmoplantar keratoderma, Bart‑Pumphrey syndrome, pseudoxanthoma elasticum)
- Acquired (secondary to repetitive trauma, occupational stress, or psychological behaviors such as finger biting)
- Associated conditions: Dupuytren disease, Peyronie disease, Ledderhose disease, hyperkeratosis, oral leukoplakia, and occasionally systemic disorders.
Clinical Presentation
- History: Most patients are asymptomatic. Lesions develop gradually, often linked to repetitive trauma. Cosmetic concerns are common, while pain or functional impairment is rare.
- Examination: Firm, well‑defined dermal papules, nodules, or plaques (0.5–3 cm) on the extensor surfaces of PIP or MCP joints. Lesions may appear at other bony prominences if subjected to repeated injury.
Causes and Risk Factors
- Occupational trauma: Repetitive motions (e.g., poultry workers, manual laborers).
- Sports trauma: Boxers, surfers (“surfer’s knots”), athletes with repetitive friction.
- Behavioral causes: Finger biting or sucking in children, self‑induced trauma in bulimia patients.
- Genetic associations: Familial keratoderma, Bart‑Pumphrey syndrome, pseudoxanthoma elasticum.
- Other associations: Dupuytren disease, Peyronie disease, Ledderhose disease, and rare links to systemic conditions.
Management
Treatment is challenging, as medical and surgical interventions are often ineffective.
- Conservative measures: Avoidance of repetitive trauma, protective gloves, occupational modification.
- Medical options: Intralesional corticosteroids or fluorouracil, keratolytics (salicylic acid, urea), silicone gel sheeting, splints or casts.
- Surgical options: Reserved for functional impairment. Recurrence is common if trauma persists, and complications such as scarring, keloid formation, or tendon injury may occur.
- Adjunctive care: Psychiatric support for behavioral causes.
Conclusion
Knuckle pads are benign but persistent lesions, most often linked to repetitive trauma or genetic predisposition. While treatment options exist, outcomes are variable, and recurrence is common. Preventive strategies and patient education remain central to management.
指關節墊（Knuckle Pads）：概述與臨床見解
定義
指關節墊是一種良性、無症狀、界限清楚、堅硬、皮膚色的丘疹、結節或斑塊，位於掌指關節（MCP）及指間關節（IP）背側皮膚。常與運動或職業相關的反覆外傷有關。
歷史背景
Garrod 於 1893 年首次在醫學文獻中描述指關節墊，但其存在可追溯至文藝復興時期。Allison 等人指出，米開朗基羅的雕塑如《大衛像》、《摩西像》、《勝利像》及《朱利亞諾·德·美第奇像》均顯示了指關節墊的特徵。值得注意的是，「knuckle pad」一詞並不完全準確，因為大多數病例的病灶位於近端指間關節（PIP），而非真正的指關節。
病因與病理生理
指關節墊可能為：
- 特發性
- 遺傳性（如掌蹠角化症、Bart‑Pumphrey 綜合徵、假黃瘤彈性症）
- 後天性（反覆外傷、職業性壓力、心理行為如咬手指）
- 相關疾病：Dupuytren 病、Peyronie 病、Ledderhose 病、角化過度、口腔白斑，偶與系統性疾病相關。
臨床表現
- 病史：大多數患者無症狀。病灶逐漸形成，常與反覆外傷有關。疼痛或功能障礙罕見，但美容困擾常見。
- 體檢：在 PIP 或 MCP 關節伸肌面可見界限清楚、堅硬的皮膚丘疹、結節或斑塊，大小約 0.5–3 公分。若持續受外傷，病灶可出現在任何骨性突起，但 PIP 關節最常受累。
致病因素與危險群
- 職業性外傷：如家禽加工廠工人反覆摩擦 PIP 關節。
- 運動性外傷：拳擊手、衝浪者（「衝浪者結」）等。
- 行為性因素：兒童咬手指或吸吮手指；神經性厭食或暴食症患者以手指誘發嘔吐。
- 遺傳性疾病：掌蹠角化症、Bart‑Pumphrey 綜合徵、假黃瘤彈性症。
- 其他相關：Dupuytren 病、Peyronie 病、Ledderhose 病，偶與食道癌、角化過度、杵狀指等相關。
治療與管理
治療困難，藥物或手術效果有限。
- 保守措施：避免反覆外傷、佩戴防護手套、改變工作方式。
- 藥物治療：皮內注射糖皮質激素或氟尿嘧啶、角質溶解劑（如水楊酸、尿素）、矽膠片、暫時性夾板或石膏固定。
- 手術治療：僅在功能受損時考慮。復發常見，若外傷持續存在更易復發。手術併發症包括瘢痕、蟹足腫或肌腱損傷。
- 輔助治療：心理治療（針對咬手指或吸吮行為）。
結論
指關節墊是一種良性但持續存在的皮膚病灶，常與反覆外傷或遺傳因素相關。治療效果有限，復發率高。預防措施與患者教育是管理的核心。