Pilomatrixoma: A comprehensive 32-year analysis of clinical and histopathological findings of 1235 patients treated at Mayo Clinic

Abstract

Research on pilomatrixoma has been limited, with most publications being case series or secondary reviews. This study aimed to analyze data from 1235 cases of pilomatrixoma to provide comprehensive information on demographic distribution, clinical presentations, and histopathological features of pilomatrixoma. A retrospective review was conducted between 1992 and 2024. The pathology database revealed 1235 confirmed cases. There was no significant sex predilection. The age distribution showed a bimodal pattern, with a childhood peak and a second, lower peak between ages 50 and 75 years (mean, 41.3±25.6 years; range, 6 months-92 years). The most common location was the head (45.1%). Multiple occurrences were rare (4%), and we found an association between increased age and decreased risk of multiple manifestations (OR=0.97, P<0.001). Forty patients (3.2%) were reported to have genetic syndromes. Pilomatrixoma was considered in the preoperative diagnosis in 490 cases (37.2%). Additionally, pilomatrixoma with atypical or proliferating features was detected in 24 cases (1.8%). Logistic regression revealed that age is a predictor for the likelihood of developing proliferating or atypical pilomatrixoma (OR=1.04, P<0.001). Among the 137 cases with preoperative imaging, ultrasonography was used the most, but the sensitivity was 29.2%. The recurrence rate was 2.4% among our sample. Recurrence showed no association with age, location, procedure type, pilomatrixoma size, or pathological findings. In conclusion, pilomatrixomas are infrequently suspected preoperatively. Considering the patient's age, the size and location of the lesion may help distinguish it from other benign masses. Recurrence or malignant transformations are extremely rare after complete removal.