The Study of the Clinical, Histopathological and Pathogenetic Feature of Pilomatricoma / 대한피부과학회지

ABSTRACT

BACKGROUND: Pilomatricoma is a cystic neoplasm with differentiation toward hair cortex cells. Although it is characterized by several features such as cellular constitiuents, stromal change and inflammation, it is difficult to interpret the histopathogenesis of the lesions, and there is no comprehensive understanding about the evolution of the tumor. OBJECT The purpose of this study was to characterize the clinical and histopathologic feature of pilomatricoma and to suggest the growth pattern and evolutional stage of this tumor. METHOD: Thirty-eight cases with pilomatricoma in 34 patients who had visited Korea University Hospital during the last 10 years have been collected. We studied the clinical and histopathological characteristics of the cases and tried to classify evolutional stages of them and to elucidate the growth pattern. RESULTS: Most of the tumors were solitary lesions except four patients, who showed two lesions simultaneously. The male to female ratio was 11.1. The average age was 16.25 years (9months to 43 years) and 35 cases(92%) were developed in the patients younger than 30 years old. The predilection sites were arm(61%), face(18.2%), neck(13%), thigh(5.2%), shoulder(2.6%) in order. The duration of lesions was from 10 days to 3 years in known cases, with mean duration of 9.8months. Histopathologically tumor size was from 0.3cm to 1.9cm in diameter, with average value of 0.89cm. 29 cases showed inflammatory reaction variably in its severity involving giant cells. Calcification was observed in 22 cases and two of them showed ossification. According to four stage system of previous study, we categorized our cases into the 3 early stage, 8 fully developed stage, 15 early regressive stage, and 12 late regressive stage. Peripheral basaloid epithelium surrounding the tumor was found in 17 cases. 3 cases were surrounded by epithelium perfectly, and 5cases were surrounded by half or more. CONCLUSION: Pilomatricoma is not a cyst but a cystic neoplasm that consists principally of rapidly growing basaloid cells that form well-defined lobular aggregations of diverse sizes and shapes. It shows variable features with differentiation. Since previous four staging system were not clearly differentiated in each stage, we divided pilomatricoma into three phases, developing phase, proliferative phase and regressive phase, according to the constituents of basaloid cells in the periphery.