Blastic phase of myeloproliferative syndrome coexisting with a malignant teratoma.

A myeloproliferative condition in blastic phase is described in an 18-year-old male who was also found to have a mediastinal malignant teratoma. Myeloid metaplasia was found in the lymph nodes and spleen, and an infiltration of granulocytic blast cells was observed in the bone marrow and the lymph nodes. Aneuploidy with an extra chromosome (trisomy 8) was present in bone marrow cells. To our knowledge the combination of a myeloproliferative disorder and a malignant teratoma has not been earlier described.