solid pattern yolk sac tumor

Yolk sac tumors may exhibit numerous patterns. One that has received little attention overall, yet is not uncommon, is a solid pattern, which is especially prone to misinterpretation, usually as seminoma, in biopsy specimens from metastatic or mediastinal sites.

Solid yolk sac tumor can generally be recognized by careful morphologic evaluation, especially its association with other yolk sac tumor patterns, the presence of intercellular band-like deposits of basement membrane, occasional microcysts, nuclear pleomorphism, intracellular hyaline globules, and usual absence of lymphocytes.

In difficult cases a concise immunohistochemical panel consisting of AE1/AE3, glypican 3, and OCT3/4 distinguishes solid yolk sac tumor from other neoplasms.

α-fetoprotein stains are commonly negative or weak and focal in solid yolk sac tumor and cannot be solely relied on for diagnosis.

Common CD117 positivity in solid pattern yolk sac tumors makes it an unreliable discriminator between yolk sac tumor and seminoma.

References

 Solid pattern yolk sac tumor: a morphologic and immunohistochemical study of 52 cases. Kao CS, Idrees MT, Young RH, Ulbright TM. Am J Surg Pathol. 2012 Mar;36(3):360-7. PMID: 22261704