每日一题_2026.01.01

A 5-week-old boy was brought in for evaluation of a painful lump on his scalp that had been present since birth. The otherwise healthy baby had been born at term. Ultrasonography of the lesion showed a subcutaneous structure of mixed echogenicity. Physical examination and magnetic resonance imaging of the head is shown. What is the most likely etiology of the lump?

一个出生五周的男婴因头皮上自出生以来就存在的疼痛性肿块前来就诊。这个其他方面健康的婴儿为足月出生。对该病变的超声检查显示皮下结构呈混合回声。头部体格检查和磁共振成像如图所示。该肿块最可能的病因是什么？

A. Atretic cephalocele闭锁性脑膨出

B. Cephalohematoma头颅血肿

C. Dermoid cyst皮样囊肿

D. Lipoma脂肪瘤

E. Meningocele脑膜膨出

答案解析：

诊断为闭锁性脑膨出（atretic cephalocele）。脑膨出是指颅内容物通过颅骨缺损处疝出。当其中不含神经组织时，就称为“闭锁性”脑膨出。在病变周围看到一圈颜色深、质地较粗的毛发，符合“毛领征（hair collar sign）”，提示可能存在神经管缺陷，因此没有进行活检。

MRI 显示：

• 颅外囊性病变；
• T2 加权像高信号、T1 加权像低信号。

同时，还偶然发现了Blake 囊囊肿（Blake’s pouch cyst）——一种位于后颅窝的囊性病变。

随后进行了神经外科手术切除该病变，随访至 1 岁时，患儿发育正常。

正确答案：A