To summarize the clinical characteristics of pilomatricoma in children and analyze the preoperative diagnostic method.

468 cases (479 tumors) of pilomatricoma in children were treated in Department of Plastic and Maxillofacial Surgery, Wuhan Children’s Hospital from January 2013 to January 2018. All cases were confirmed by pathology after operation. There were 224 males and 244 females, aged from 3 months to 13 years and 10 months. The general situations, case histories, physical signs, auxiliary examinations and preoperative diagnoses of all patients were analyzed retrospectively. SPSS 22.0 software was used for statistical analysis of data. Median or mean±standard deviation was used for describing measurement data, and component ratio or rate was used for describing counting data.

The peak age was 0-2 years old, accounting for 47.22%(221/468). The male to female ratio was 1∶1.09. The most common site of lesions was head(348 cases), followed by neck(76 cases), upper limbs(40 cases), trunk(10 cases) and lower limbs(5 cases). All patients had histories of subcutaneous mass, 85.90%(402/468) had histories of tumor growth, 16.24%(76/468)had pain, 7.91%(37/468) had histories of infection, 28.42%(133/468) had histories of previous treatment, and 12.18%(57/468) had histories of external stimulation. The masses were (1.2±0.6) cm(from 0.3 cm to 3.5 cm) in diameter. By inspection, 98.33%(471/479) of skin overlying the tumor were intact, and 63.29%(269/425) were pale blue. By palpation, 79.62%(375/471) of masses were hard, 100% adhered to the skin, 94.15%(451/479) didn’t cause tenderness, 31.73%(152/479) appeared "tent sign" , and 27.77%(133/479) appeared "teeter-totter sign" . The diagnostic accuracy rate of ultrasonographic examination was 75.24%(155/206). 31.55%(65/206) showed hypoechoic nodule containing internal hyperechoic dots, 27.67%(57/206) showed hyperechoic band with wide acoustic shadowing below. 88.83%(183/206) of Color Doppler Flow Imaging showed peripheral blood flow signal around the nodule, and the internal blood flow signal decreased or disappeared. The diagnostic accuracy rate of CT examination was 98.44%(126/128), 58.59%(75/128) of plain CT scans showed high density mass shadows of which the internal densities were homogeneous or heterogeneous. 39.84%(51/128) of plain CT scans showed soft tissue density mass shadows of which the internal densities were heterogeneous, and the dot high density shadows in different size scattered. The diagnostic accuracy rate of needle aspiration cytology was 61.54%(8/13). The preoperative diagnostic accuracy rate was 81.63%(391/479).

Typical pilomatricoma often occurs on a child’s head. The overlying skin is pale blue. The tumor is hard in texture, adheres to the skin, and appears a "tent sign" or "teeter-totter sign" . Ultrasonography and CT examinations suggest calcification in the subcutaneous lesion, which is helpful for preoperative diagnosis. Needle aspiration cytology can be used for differential diagnosis of atypical case.

Child; Pilomatricoma; Clinical characteristics; Diagnosis