钙化上皮瘤的影像表现及病理基础

Imaging manifestations and pathological features of pilomatricoma

目的:分析钙化上皮瘤的CT及MRI表现,并探讨其病理基础。方法:回顾性分析17例经手术病理证实的钙化上皮瘤患者影像学资料并复习相关文献,其中8例行CT平扫及增强扫描,6例行MR平扫及增强检查,2例仅行CT平扫,1例先行X线片,后行MR平扫加增强检查。结果:10例CT共13个病灶。8个病灶见钙化,其中5个病灶完全钙化。2个病灶见坏死。10个病灶边界清清楚,3个瘤周见絮状稍高密度影。8例CT增强扫描共11个病灶,其中3个轻度强化,5个不均匀中度强化,3个病灶完全钙化无强化。6例MR均为单发,2例T1WI呈等信号,T2WI呈外周高中央低信号,DWI呈环状高信号,增强呈“环靶征”。2例T1WI呈等或稍高信号,T2WI呈高信号,内见微囊状更高信号,灶周可见斑片状高信号,增强不均匀强化。2例T1WI呈稍低信号,T2WI均呈稍高信号,增强不均匀强化。1例X线片呈高密度,T1WI呈低信号,T1WI压脂呈不均匀稍高信号,T2WI压脂呈高低混杂信号,增强扫描不均匀强化,以中央强化较为明显。结论:钙化上皮瘤的影像表现有一定特征,当病灶位于皮下,边界清楚,CT见广泛泥沙样或致密的局灶性钙化,MR上见微囊状改变,增强扫描轻至中度强化,尤其呈“环靶征”表现时,应考虑到PM的诊断。

Objective:To investigate CT and MRI imaging features of pilomatricoma with radiological-pathological correlation.Methods:We retrospectively analyzed imaging findings of 16 patients with head and neck pilomatricoma that were pathologically confirmed.Moreover,relevant literature was reviewed.Among the 16 patients,eight received plain CT with contrast-enhancement,six patients received plain MRI with contrast-enhancement,and two only received plain CT,one had plain X-ray film first,followed by plain MRI with contrast-enhancement.Results:10 cases by CT displayed a total of 13 lesions.Calcification was seen in 8 lesions,of which five are completely calcified.Two lesions showed necrosis.Ten lesions were well-circumscribed,and slightly higher peritumoral density was seen in 3 lesions.CT scans were performed in 8 patients with 11 lesions,of which three were slightly enhanced,five were inhomogeneous and moderately enhanced,and three were completely calcified without enhancement.All 6 cases by MR were single lesions.In two cases,T 1WI showed iso-intensity,T 2WI showed homogeneous hypointensity in the center and ring-like hyperintensity on the periphery.And DWI showed circular hyperintensity with"ring-target"enhancement.In two cases,T 1WI showed isointensity or mild hypeintensity,T 2WI showed hypeintensity,and T 2WI fat suppression showed heterogeneously enhanced microcystic appearances.In another two cases,T 1WI showed slight hypointensity,and T 2WI showed slight hyperintensity with heterogeneous enhancement.In one case,X-ray plain film showed high density;T 1WI showed low signal;T 1WI fat suppression showed slightly higher signals;T 2WI fat suppression showed mixed high and low signals with more obvious central enhancement.Conclusions:Head and neck pilomatricoma presents with certain characteristics.PM diagnosis should be considered in the following circumstances.Lesion is subcutaneous and well-circumscribed,with extensive sand-like or dense focal calcification shown on CT,and microcystic appearance on MR,with mild to moderate enhancement,especially with a"ring-target"appearance.