• Usually spinal cord tumor, may arise is soft tissue in sacrococcygeal area separate from cord
• Resembles pilonidal cyst clinically, but 20% metastasize

• 25 year old Asian woman with enlarging, painless, subcutaneous mass on intergluteal fold (J Clin Med Res 2012;4:61)
• 39 year old man with gradually increasing bilateral buttock pain (Asian Spine J 2011;5:68)

• Well circumscribed, easily enucleated

Two ovoid mass

• Resembles CNS tumor
• Small blue cells forming well defined perivascular structures, surrounded by dense fibrous tissue

Epithelioid cells with some cytoplasmic clearing

Cribriform pattern

Solid sheets and cords

L: S100; R: GFAP

L: AE1AE3; R: CAM5.2

Columnar cells

Radial processes

• GFAP & S100, may be cytokeratin+, focally EMA+ (Diagn Pathol 2008;3:40)

• Ependymal rests: clusters of cells < 0.5 cm in dermis/subcutaneous tissue near pilonidal sinuses

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