Abstract

Atretic cephalocele is an outpouching of meninges protruding through the skull connected via a fibrous stalk to underlying structures. Diagnosis relies on imaging to identify skull defects and herniation contents. Although the developmental abnormality causing these lesions is thought to involve the neural tube, bone, and surrounding skin, there are few reports of associated histopathologic findings due to low incidence. Here, we present two cases of atretic cephalocele, focusing on their cutaneous histopathologic features. The first case involves a 12-month-old girl with a red, hairless patch on her posterior scalp, initially diagnosed as aplasia cutis congenita. Imaging revealed a parietal cephalocele with a stalk extending through a bony defect. The second features a 7-month-old boy with a soft hairless nodule on the parietal scalp, identified through imaging as a cystic focus with a fibrous stalk connecting to the intracranial compartment. Histologic examination of both cases revealed dermal and subcutaneous pseudo-vascular spaces. Immunohistochemistry showed negative glial fibrillary acidic protein (GFAP) and epithelial membrane antigen (EMA) positivity in meningothelial cells. One case demonstrated increased proliferation of eccrine sweat glands and absence of hair follicles in the adjacent dermis, while the other lesion lacked all skin adnexa. Although previous studies have reported hamartomatous changes in adipose cells and blood vessels, only one case previously reported hamartomatous sweat gland proliferation. Our cases provide further insight into the histopathological presentation of cutaneous adnexa and structures involved in atretic cephaloceles and emphasize the need for additional research, given the complex histologic variations that currently pose diagnostic challenges.