Biphenotypic lymphoblastic lymphoma. An unusual tumor with lymphocytic and granulocytic differentiation.

An unusual example of a lymphoblastic lymphoma with evidence of both T-lymphocytic (Leu-1, Leu-2, Leu-3, OKT-6, terminal transferase-positive) and immature granulocytic (Mo1, chloroacetate esterase, lysozyme, alpha-1-antitrypsin-positive) cell proliferations was studied. The tumor arose in the oropharynx of a 39-year-old man without evidence of blood or bone marrow involvement. This tumor has been termed a "biphenotypic lymphoblastic lymphoma," and the origin of which appears to be from uncommitted progenitor cells capable of both lymphoid and myeloid differentiation. Biphenotypic lymphoblastic lymphomas, like biphenotypic leukemias, may occur more commonly than is appreciated, and may account for reported cases of acute myeloblastic leukemia after lymphoblastic lymphoma.