Erythroleukemia in a Child: Value of Immunocytochemistry and Transmission Electron Microscopy in Its Diagnosis

摘要

Acute lymphoblastic leukemia (ALL) is the most common leukemia presenting in children. Morphologically, the French-American-British classes L1 and L3 are distinct by light microscopy; however, the heterogeneity of class L2 may result in confusion with the M1, M5, and M6 categories of acute myeloid leukemia. Histochemical stains are frequently valuable in classifying such leukemic cells and terminal-deoxynucleotidyl transferase (TdT) is positive in about 90% of ALL. Acute erythroleukemia is extremely uncommon in childhood. Malignant erytroblasts in this disorder frequently demonstrate large block and diffuse blush periodic acid-Schiff (PAS) positively in contrast to the granular block positivity seen in many cases of L1 and L2 ALL. The poor prognosis of erythroleukemia makes accurate diagnosis imperative and necessry for the appropriate selection of chemotherapy. We report a case of erythroleukemia in a child that mimicked ALL and required immunocytochemistry and transmission electron microscopic (TEM) examination of unstained and untreated tissue to establish the diagnosis.