Familial cerebral cavernous malformation syndromes are most commonly caused by mutations in one of three genes. The overlap of these genetic malformations with other acquired neoplastic lesions and congenital malformations is still under investigation. To the best of our knowledge, the concurrent occurrence of familial cavernous malformations and ependymoma has not been previously reported in the literature. Herein, we describe a patient with familial cerebral cavernous malformation syndrome and posterior fossa ependymoma. A 17-year-old asymptomatic male was referred to our outpatient neurosurgery clinic after genetic testing identified a familial KRIT1 (CCM1) mutation. The patient's sister had presented with a seizure disorder previously; multiple cavernous malformations were discovered, and a symptomatic large cavernous malformation required a craniotomy for resection. Two years later, she was diagnosed with follicular thyroid cancer due to HRAS (c.182A>G) mutation. The patient and his sister were found to have a novel germline KRIT1 disease-causing variant (c.1739deletion, p.ASN580Ilefs*2) and a variant of uncertain significance, potentially pathogenic (c.1988 A>G, p.Asn663Ser) in cis in CCM1 (KRIT1), of paternal inheritance. Due to the presence of genetic abnormalities, the patient underwent screening imaging of his neuraxis. Multiple cavernous malformations were identified, as was an incidental fourth ventricular mass. Resection of the fourth ventricular lesion was performed, and histopathological examination was consistent with ependymoma. We report a unique case of posterior fossa ependymoma in an individual with a familial cerebral cavernous malformation syndrome and a novel genetic abnormality in KRIT1. The association of these two findings may be valuable in determining a potential genetic association between the two pathologies and elucidating the pathogenesis of both cavernous malformations and ependymomas.

家族性脑海绵状畸形综合征最常见是由三个基因之一的突变引起的。这些遗传畸形与其他获得性肿瘤性病变和先天性畸形的重叠仍在研究中。就我们所知，家族性海绵状畸形和室间隔瘤并发的发生以前尚未在文献中报道。在此，我们描述了患有家族性脑海绵状畸形综合征和后颅窝室间隔膜瘤的患者。经过基因检测发现家族性KRIT1（CCM1）突变后，一名17岁无症状的男性被转诊至我们的门诊神经外科诊所。病人的姐姐以前有癫痫发作。发现了多个海绵状畸形，有症状的大海绵状畸形需要开颅手术切除。两年后，她因HRAS（c.182A> G）突变而被诊断为滤泡性甲状腺癌。患者和他的妹妹被发现有一个新的种系KRIT1致病变体（c.1739deletion，p.ASN580Ilefs * 2）和一个不确定的，具有潜在致病性的变体（c.1988 A> G，p.Asn663Ser）。父系继承的CCM1（KRIT1）中的顺式。由于存在遗传异常，患者接受了神经元筛查。鉴定出多发性海绵状畸形，以及偶发的第四脑室肿块。切除第四脑室病变，组织病理学检查符合室间隔膜瘤。我们报告了家族性脑海绵状畸形综合征和KRIT1的新型遗传异常的个体中后颅窝室间隔瘤的独特案例。这两个发现的关联可能对确定两种病理之间的潜在遗传关联以及阐明海绵状畸形和室管膜瘤的发病机理具有重要意义。