Cytodiagnosis of extragonadal pure yolk sac tumor of sacrococcygeal region

Yolk sac tumors (YST) are rare in extragonadal location. Cytologic diagnosis of YST in such instances may be a challenge to the pathologist. We studied Fine needle Aspiration (FNA) material from a sacrococcygeal mass in a 18-month-old female child presenting with a progressively increasing sacrococcygeal mass. Cytologic features include large pleomorphic balls of tumor cells with high nuclear to cytoplasmic ratios, papillary or micro-glandular pattern of growth, cytoplasmic and intra-nuclear vacuoles, and prominent nucleoli. Per Iodic Acid Schiff (PAS) positive intra-cytoplasmic as well as extracellular hyaline globules were also seen. The subsequent biopsy was consistent with the FNA diagnosis, and immuno-histochemically, the tumor cells were positive for Alpha Feto Protein (AFP) supporting the diagnosis.