Clinical, Pathological, and Imaging Study of Pilomatrixoma: A Retrospective Study

A retrospective analysis was conducted on the clinical, pathological, and imaging features of 471 cases of pilomatrixoma, aiming to enhance clinicians' understanding of pilomatrixoma.

A total of 471 cases of pilomatrixoma diagnosed and surgically treated in the Affiliated Hospital of Southwest Medical University from August 1999 to July 2024 were retrospectively analyzed. Some cases were also diagnosed through preoperative fine needle aspiration, as well as ultrasonography, computed tomography (CT), and magnetic resonance imaging (MRI).

Of these 471 patients, 224 (47.6%) were male, and 247 (52.4%) were female. Their ages ranged from 8 months to 90 years, with an average age of 18.2 years. The highest incidence of pilomatrixoma was observed in patients aged between 0 and 10 years, accounting for 46.5% (219/471). The most common site of pilomatrixoma is the face, followed by the neck. The most common area of the face is the parotid gland region, accounting for 24.8% (61/246) of facial cases. Histology and cytopathology revealed that the tumor cells usually consisted of basaloid cells and eosinophilic shadow cells, and inflammatory cells, foreign body giant cells, and calcifications were seen. Additionally, the ultrasonography showed a mass with calcification, a strong echo band, and parenchyma without calcification. The pilomatrixoma should be considered when the tumor presents as soft-tissue density with varying degrees of calcification, well-defined oval or circular nodules on CT, and characteristic reticular and annular hypersignal on T2WI and T2WI + FS on MRI.

Pilomatrixoma is commonly found on the face and neck of adolescent females. Cytopathology, ultrasound, and imaging features can provide clinical clues, and histopathology can make the final diagnosis. Complete surgical resection is the preferred treatment.