Complex pathological diagnosis of granulocytic sarcoma: apropos of a case.

The diagnosis of granulocytic sarcoma can be very difficult when there is no demonstrable abnormality in the peripheral blood or bone marrow. We present the diagnostic algorithm of granulocytic sarcoma by reporting on a case mimicking large cell lymphoma without previous manifestation of acute myeloid leukemia or a myeloproliferative disorder. After standard histoprocessing, we used immunohistochemical and molecular biological methods to analyze our case. The lymph node showed diffuse infiltration of immature blast cells resembling large cell lymphoma. However, immunohistochemistry did not support this diagnosis. The tumor cells showed LCA, bcl-2, CD43, CD34 and myeloperoxidase positivity. We also detected bcl-2 gene rearrangement. In case of a lack of a specific histological picture, particularly in poorly differentiated tumors, only some minor histological signs in combination with immunohistochemistry and molecular diagnostic methods can help to render the correct diagnosis.