Mediastinal mixed germ cell tumor

Discussion:

The patient when on surgical removal of the mediastinal mass as well as with 4 regional lymph nodes and pleural nodule.

Histology

MICROSCOPIC FEATURES:

Mediastinal mass: Sections  show  a  non-seminomatous   mixed  germ cell  tumor  showing extensive tumor necrosis.  The percentage of viable tumor is estimated at  20%.  100% of  viable  tumor is  yolk  sac tumor   showing a  variety of patterns including some cystic areas  with hylaine globules in cells lining a cyst.  Schiller-Duval bodies are readily identified.  The left-sided soft grey nodule is a keratin-filled cyst surrounded by entirely necrotic tissue consistent with entirely necrotic teratoma.  No immature teratoma component is identified.   A  few foci  showing  larger  more  pleomorphic  cells are present which  are the  pleomorphic  cell type  pattern of yolk  sac tumor (alpha feto-protein  positive,  CD30 and  beta-HCG negative).   There is no evidence of embryonal carcinoma,  seminoma or choriocarcinoma on routine or immunohistochemistry stains. Alpha feto-protein stain shows only a few foci of positivity within the  yolk sac tumor.

Pleural nodule: Sections  show both viable  and necrotic  yolk sac tumor  with a small amount of attached  diathermied skeletal  muscle.  Focally  viable yolk sac tumor abuts an inked margin immediately adjacent to an area of diathermied margin, over a distance of approximately 5 mm

Lymph nodes: no viable tumor

FINAL DIAGNOSIS: 

  1. Mediastinal tumor - non-seminomatous mixed germ cell tumor.
  2. Approximately 20% of tumor viable.
  3. 100% of viable  tumor is  yolk sac tumor.   Entirely  necrotic teratoma also  present.  No  immature  teratoma   identified.
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