ABSTRACT
Benign epithelial skin cysts containing multiple components of the folliculo-sebaceous apocrine unit are only rarely reported in the literature. Here, we describe a 12-year-old girl who presented with a cystic mass on the vertex of her scalp. Upon resection, it showed a hybrid benign skin cyst with interesting histological features of both pilar and apocrine differentiation. The clinicopathological and imaging findings of this unusual skin cyst, successfully managed by a plastic surgeon and neurosurgeon, are described. Pathologists and clinicians should be aware of this type of skin cyst rarely encountered in their clinical practice.
ABSTRACT
A 48-year-old woman was referred with an 18-year history of focal-onset seizures. She also reported years-long slowly progressive right-sided weakness that was corroborated on examination. Repeated brain MRIs over 15 years showed multifocal left hemispheric T2 fluid-attenuated inversion recovery-hyperintense lesions with patchy enhancement and microhemorrhages, no diffusion restriction, and a left cerebellar infarct (Figure 1, A-F). Only 2 nonspecific white matter lesions were seen contralaterally, indicating largely unihemispheric disease. Differential diagnosis included unilateral primary angiitis of the CNS (PACNS), Rasmussen encephalitis, and myelin oligodendrocyte glycoprotein antibody-associated disease.1 Serum and CSF testing for autoimmune, infectious, and malignant etiologies and whole-body fluorodeoxyglucose-PET, whole-exome genetic sequencing, and MR vessel-wall imaging were nondiagnostic. Brain biopsy revealed vasculitis (Figure 2, A-F), and the patient was diagnosed with unilateral PACNS. Treatment with mycophenolate mofetil has been initiated. Unilateral PACNS is a rare unihemispheric disease characterized by an indolent course and seizures, recognition of which is critical to accurate diagnosis.1,2.