Clinical and pathological features of pilomatrixoma in children: a retrospective study.

Introduction Pilomatrixoma is a benign skin neoplasm that is common in children and is often misdiagnosed. This study aimed to summarize the clinical and pathological features of pilomatrixoma in children. Methods Data on demographic information, clinical and pathological features, diagnosis, and treatment of 171 patients with pilomatrixoma from Shenzhen Baoan Women's and Children's Hospital were collected and analyzed retrospectively. Results The mean age of the patients was 5.7 (standard deviation (SD) = 3.9) year-old, and there were two age peaks (≤1 year-old, 5-11 years old) and two age valleys (2-4 years old, ≥ 12 years old). The mean disease course was 9.3 (SD = 14.1) months, 69.0%, 86.5%, and 95.3% of the patients' disease course in 6 months, 12 months, and 24 months, respectively. The mean tumor volume is 0.6 (SD = 1.0) cm3, 81.3% of the patients' tumor volume ≤ 1.0 cm3. Tumors were distributed sequentially in the head and neck (77.2%), upper limbs (12.9%), trunk (7.6%), and lower limbs (2.3%). The correct rates of clinical and ultrasonic diagnosis were 50.9% and 38.6%, respectively. The two most common pathological features of pilomatrixoma were shadow cells (99.4%) and basaloid cells (94.7%). There were no significant differences in age, disease course, or tumor volume between the male and female patients (P > 0.05). The age and tumor volume of the patients in different body parts were significantly different (P1 = 3.10E-05 and P2 = 5.60E-05, respectively). The correlation between the disease course and tumor volume was positively significant (P ≤ 0.05). There was a significantly correlation between the disease course and tumor volume in patients with tumors at upper limbs (P = 0.03). Conclusion The age of children with pilomatrixoma presented two peaks and two valleys. Most patients had disease courses in 24 months and with tumor volumes ≤ 1.0 cm3. The correct rates of clinical and ultrasonic diagnosis were relatively low. The head and neck are the most common distribution sites of pilomatrixoma, shadow cells and basaloid cells are the most common pathological features. The tumor volume is positively correlated with disease course in patients with pilomatrixoma.