GFAP-Negative Subcutaneous Sacrococcygeal Extraspinal Ependymoma

Ependymomas are slowly growing glial tumors derived from the ependymal cells and usually occur in the central nervous system (CNS). Ependymomas rarely occur outside of the CNS and they are called extraspinal ependymomas. In spite of their metastatic potential, extraspinal ependymomas can be misdiagnosed for other benign mass like pilonidal cysts. The diagnosis is confirmed by histopathology and most of the cases are known to show glial fibrillary acidic protein (GFAP), S-100 protein, and keratin (AE1AE3) immunoreactivity. Herein, we present a case of GFAP-negative ependymoma, which presented as asymptomatic subcutaneous tumor of the left buttock and was clinically misdiagnosed as epidermal cyst. Our case indicates that ependymomas cannot be ruled out by lack of GFAP immunoreactivity and an asymptomatic subcutaneous mass could be a malignant tumor like ependymomas, which requires careful examinations

Bi-allelic CSF1R Mutations Cause Skeletal Dysplasia of Dysosteosclerosis-Pyle Disease Spectrum and Degenerative Encephalopathy with Brain Malformation

Colony stimulating factor 1 receptor (CSF1R) plays key roles in regulating development and function of the monocyte/macrophage lineage, including microglia and osteoclasts. Mono-allelic mutations of CSF1R are known to cause hereditary diffuse leukoencephalopathy with spheroids (HDLS), an adult-onset progressive neurodegenerative disorder. Here, we report seven affected individuals from three unrelated families who had bi-allelic CSF1R mutations. In addition to early-onset HDLS-like neurological disorders, they had brain malformations and skeletal dysplasia compatible to dysosteosclerosis (DOS) or Pyle disease. We identified five CSF1R mutations that were homozygous or compound heterozygous in these affected individuals. Two of them were deep intronic mutations resulting in abnormal inclusion of intron sequences in the mRNA. Compared with Csf1r-null mice, the skeletal and neural phenotypes of the affected individuals appeared milder and variable, suggesting that at least one of the mutations in each affected individual is hypomorphic. Our results characterized a unique human skeletal phenotype caused by CSF1R deficiency and implied that bi-allelic CSF1R mutations cause a spectrum of neurological and skeletal disorders, probably depending on the residual CSF1R function