Cramer S F
Am J Clin Pathol. 1981 Mar;75(3):425-9. doi: 10.1093/ajcp/75.3.425.
Subungual keratoacanthoma is a benign tumor of the fingers and toes that can simulate malignancy and present significant diagnostic problems for both the clinician and the pathologist. It is a rapidly growing nail-eroding tumor that may cause pain, swelling, and inflammation. Radiographs consistently demonstrate a lytic cup-shaped lesion of the tip of the distal phalanx, raising the question of malignancy. Because the lesion lacks the clinical appearance of keratoacanthoma of follicular origin, the diagnosis of keratoacanthoma may not be given clinical consideration. However, the histologic appearance of a central cavity filled with keratinous debris and lined by intensely keratinized, well-differentiated neoplastic squamous epithelium mimics the appearance of keratoacanthoma of follicular origin. The subungual location of the tumor, rapid growth with pressure erosion of the tip of the distal phalanx, and typical histologic features define this keratoacanthoma of nail matrix origin as a distinct entity. Recognition of the entity is crucial if the diagnosis of squamous cell carcinoma, which would lead to an unnecessary amputation, is to be avoided. Ultrastructurally, the keratinization process resembles that of normal nail matrix.
甲下角化棘皮瘤是手指和脚趾的一种良性肿瘤，可模拟恶性肿瘤，给临床医生和病理学家带来重大诊断难题。它是一种生长迅速的侵犯指甲的肿瘤，可引起疼痛、肿胀和炎症。X线片始终显示远节指骨末端有溶骨性杯状病变，这引发了恶性肿瘤的疑问。由于该病变缺乏毛囊源性角化棘皮瘤的临床表现，临床可能不会考虑角化棘皮瘤的诊断。然而，其组织学表现为中央腔充满角质碎屑，内衬高度角化、分化良好的肿瘤性鳞状上皮，类似于毛囊源性角化棘皮瘤的表现。肿瘤的甲下位置、远节指骨末端因压力侵蚀而快速生长以及典型的组织学特征，将这种甲床起源的角化棘皮瘤定义为一种独特的实体。如果要避免导致不必要截肢的鳞状细胞癌的诊断，认识到这一实体至关重要。超微结构上，角化过程类似于正常甲床。
