Erythroleukemic infiltration of a lymph node: use of hemoglobin immunohistochemical techniques in diagnosis

Isolated submandibular adenopathy developed in a patient who had subacute erythroleukemia. Lymph node biopsy revealed a proliferation of immature cells and scattered foci of dyserythropoietic normoblasts. Since a review of the literature revealed no detailed description of an erythroleukemic lymph node infiltrate, a histopathologic study of this node was undertaken. The immature cells were identified as erythroblasts and pronormoblasts by histochemical staining (periodic acid-Schiff reagent and chloroacetate esterase), immunohistochemical reaction (directed against hemoglobin), and electron microscopy. The diagnosis of erythroleukemic lymph node infiltrate may be missed in the absence of a high index of suspicion. It is concluded that the detection of hemoglobin within malignant cells is most helpful in establishing the diagnosis.