Cytology of fine needle aspirates of primary extragonadal germ cell tumors

OBJECTIVE: To describe the characteristic cytologic features of fine needle aspirates (FNAs) of primary extragonadal germ cell tumors (PEGCTs). STUDY DESIGN: Thirteen patients with PEGCTs, including 2 seminomas, 2 mixed germ cell tumors, immature teratomas, 1 choriocarcinoma and 5 yolk sac tumors (YSTs) were studied. The final diagnosis of PEGCT in all cases was established by histologic examination of the tumor tissues. Fine needle aspiration was done on either the primary tumor or metastatic foci. The aspirates were stained with one of the Romanovsky stains and Papanicolaou stain. RESULTS: Each type of PEGCT has its own morphologic characteristics. In seminoma, the tumor cells are large and noncohesive, with one to several distinct nucleoli; some lymphocytes are also present. YSTs show many pleomorphic cells with vacuoles in the cytoplasm and nuclei; tumor cells frequently aggregate in a microglandular or papillary pattern. Choriocarcinoma consists of syncytiotrophoblasts and cytotrophoblasts. The former are very large cells with eosinophilic cytoplasm, one to several nuclei and distinct nucleoli; the latter are medium-sized cells with vacuolated, basophilic cytoplasm and eccentric nuclei. Immature teratomas are composed of a mixture of cell types, including elongated epithelioid cells, mesenchymal cells and many large, naked, amorphous nuclei with a homogeneous chromatin pattern. Diagnosis of mixed germ cell tumor is difficult but can be made if two or more subtypes of tumor cells are observed in the FNA. CONCLUSION: Cytologic examination of FNAs of primary or metastatic lesions of PEGCTs, stained either with Romanovsky or Papanicolaou stain, is of diagnostic value for such diseases. The use of immunochemistry can help to confirm the cytologic impression.