The term PROS (PIK3CA-Related Overgrowth Spectrum) indicates a wide spectrum of overgrowth disorders related to somatic mutations in PIK3CA (phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha) pathway. We present three cases with PIK3CA mutation and clinical characteristics encompassing MCAP (megalencephaly-capillary malformation) condition but lacking all criteria to a certain diagnosis, most of all showing prevalent and peculiar involvement of cerebellar structures at MRI (magnetic resonance imaging) mainly consisting in cortical rim thickening and abnormal orientation of folia axis. These cases expand the spectrum of intracranial MRI features in PIK3CA disorders.

术语 PROS（PIK3CA 相关过度生长谱）表示与PIK3CA（磷脂酰肌醇-4,5-二磷酸 3-激酶催化亚基 α）途径中的体细胞突变相关的广泛的过度生长障碍。我们介绍了三例具有PIK3CA突变和临床特征的病例，包括 MCAP（巨脑毛细血管畸形）病症，但缺乏确定诊断的所有标准，其中最重要的是在 MRI（磁共振成像）中显示小脑结构的普遍和特殊受累，主要包括皮质边缘增厚和叶轴方向异常。这些病例扩大了PIK3CA疾病的颅内 MRI 特征范围。