临床资料患者,女,20岁。主因右足第4趾疼痛性结节2年,于2009年2月4日就诊。患者2年前无明显诱因右足第4趾甲下远端出现一硬性结节,挤压时疼痛明显,并逐渐增大。皮肤科情况:右足第4趾甲下可见一0.8cm×0.8cm大小结节,表面角化明显,有触痛(图1)。数字化X线摄影(DR)示:右侧第4远节趾骨末端见骨性密度新生物影(图2)。诊断:甲下外生 Clinical data Patient, female, 20 years old. Mainly because of right foot 4 toe pain nodules 2 years, on February 4, 2009 treatment. There was no obvious inducement in 2 years in the patient. A hard nodule appeared at the distal end of the fourth nail of the right foot. The pain was obvious and gradually increased when squeezed. Dermatology: right foot 4 under the nail can see a size of 0.8cm × 0.8cm nodules, keratosis obvious, tenderness (Figure 1). Digitizing radiography (DR) showed a new bioobject of bony density at the distal fourth phalanx toe (Figure 2). Diagnosis: A lower exogenous