Sinonasal yolk sac (Endodermal sinus) tumor in an adult female - A case report and review of the literature

Yolk sac tumor (YST), also known as endodermal sinus tumor, is a highly malignant germ cell tumor that is extremely rare in the sinonasal region, especially in adults. To the best of our knowledge, only five such cases have been reported till date (four men, one woman). We present a case of sinonasal YST admixed with transitional cell carcinoma in a 58-year-old female. Magnetic resonance imaging revealed a mass in the right ethmoid fissure infiltrating into the posterior and anterior ethmoid sinuses and nasopharynx. Positron emission tomography examination showed a maximum standardized uptake value of 6.8. Histological examination of the biopsy specimen revealed two distinct features, YST and transitional cell carcinoma, with evidence of mutual transition that indicated the composite nature of the tumor. Immunohistochemical analysis revealed positive immunoreactivity for Sal-like protein 4, α-fetoprotein and glypican3, and negative immunoreactivity for placental alkaline phosphatase, CD30 and CD117 in the YST component. P40 and P63 were detected only in transitional cell carcinoma component. The tumor was subsequently excised and four cycles of adjuvant chemotherapy at intervals of 3 weeks were administered. At 8 months after surgery, there was no evidence of tumor recurrence or metastasis. We have also presented a literature review on YST in sinusoids.