Fine-Needle Aspiration of Metastatic Central Type Primitive Neuroectodermal Tumors in Patients with a Germ Cell Tumor

Central type primitive neuroectodermal tumors (PNET) are some of the most frequent somatic type tumors derived from germ cell tumors and can metastasize. We studied the cytomorphological features of metastatic central type PNET by fine-needle aspiration (FNA).

A computerized search of our laboratory information system was performed for the 9-year period from 2005 through 2014 to identify all cytology cases in which a diagnosis of metastatic central type PNET had been rendered. A total of 5 FNA cases were collected and direct smears were reexamined.

All patients had a history of testicular or ovarian germ cell tumors. Direct smears displayed single and clusters of atypical round to oval cells with scant to moderate cytoplasm. Abundant naked nuclei were present in Diff-Quik-stained smears with mild to marked crushed artifacts and nuclear molding. Tumor cells showed fine granular chromatin, nuclear size variation (up to 1:3), and one or more small nucleoli. Pseudorosettes (Homer Wright-like rosette) were noticed in 1 case. Tumor cells were commonly positive for synaptophysin.

Metastatic PNET can be reliably diagnosed by FNA. Differential diagnoses include Ewing sarcoma/peripheral PNET, alveolar rhabdomyosarcoma, neuroblastoma, etc. It is important to be familiar with this entity to avoid diagnostic pitfalls.