Morphological features of congenital dyserythropoietic anemia type I: The role of electron microscopy in diagnosis.

INTRODUCTION: Congenital dyserythropoietic anemias are rare blood disorders characterized by congenital anemia and a wide range of morphological and functional abnormalities of erythroid precursors. OBJECTIVES: To analyze the relative frequency of both light microscopic (LM) and electron microscopic (EM) morphological features of erythroblasts in a large group of patients with molecular proven congenital dyserythropoietic anemia type I (CDAI). METHODS: We retrospectively evaluated the LM and EM of bone marrow (BM) erythroblasts in 35 patients with CDAI. Thirty-four patients carried the CDAN1 Arg1042Trp founder mutation and one the p.Pro1130Leu mutation. BM slides of 24 patients were available for LM examination. EM studies were performed in all 35 patients. RESULTS: On LM, marked erythroid hyperplasia, binuclear erythroblasts, and various non-specific dyserythropoietic features were documented in every case; internuclear chromatin bridges were detected in 19 patients (79%). In all, EM of erythroblasts revealed a spongy appearance of heterochromatin, a widening of nuclear pores, and invagination of cytoplasm into the nuclear region. CONCLUSIONS: EM studies revealed high morphological frequency of specific ultrastructural changes in erythroblasts which facilitate prompt diagnosis of CDAI. Due to low specificity of BM LM findings, when BM EM is unavailable diagnostic approach should also include other inherited anemias.

Acute basophilic leukaemia: eight unsuspected new cases diagnosed by electron microscopy.

We report eight new patients with de novo acute basophilic leukaemia (ABL) diagnosed by electron microscopy (EM) in 184 patients with poorly differentiated AML who were selected for ultrastructural analysis between the years 1989 and 2002. Morphology by light microscopy, cytochemistry, immunophenotyping and cytogenetics did not enable an accurate diagnosis in any of these patients. In almost all the patients, the blasts showed reactivity for HLA-DR and CD34. EM studies demonstrated the presence of basophilic granules in the leukaemic blasts. These granules were membrane bound and their contents varied in appearance from uniformly electron dense to partially speckled or electron lucent. Theta granules were present in only three patients and no mast-cell type granules were observed. By light microscopy, the myeloperoxidase reaction was positive in three patients in an unusual coarse granular pattern. Ultrastructural demonstration of peroxidase in the granules, nuclear membrane and profiles of endoplasmic reticulum was observed in all eight patients. The reaction in the granules showed a particular speckled pattern. The outcome was unfavourable in six of our eight patients. As a definitive diagnosis of ABL may be made only by EM, we suggest including such studies as an integral part of the diagnostic work-up of acute leukaemia cases that lack differentiation markers.

New sporadic case of congenital dyserythropoietic anemia type III in an aged woman: detailed description of ultrastructural findings.

We describe a new case of congenital dyserythropoietic anemia (CDA) type III. This least common type of CDA was diagnosed at the age of 59 in a 70-year-old woman who suffered from a young age from mild macrocytic anemia, while the long follow up since diagnosis documented a benign clinical course. No family history of blood diseases was obtained and no anemia was documented in the medical records of any of her four children. The bone marrow (BM) examination on light microscopy revealed a severe erythroid hyperplasia with the presence of giant multinucleated erythroblasts. Ultrastructural examination of the BM disclosed the presence of many large multinucleated erythroblasts bearing a variety of ultrastructural findings: nuclear clefts, autophagic vacuoles, iron-loaded mitochondria, and intracytoplasmic myelin figures. In addition, extensive hyperlobulation of the nucleus and partial loss of nuclear membrane with "spilling" of nuclear material to the adjacent cytoplasm was also noted in some of the erythroblasts. These last two findings have not been previously described in CDA III.