Erythroleukemia: A Rare Case Report
P. Da Rocha
V. M. Rebello
R. G. W. Pinto
Erythroleukemia is a rare presentation of spectrum of Acute Myeloid Leukaemia (AML) constituting about 3-4% of all the cases of AML. Here we present a case report of the same.
Acute myeloid leukaemia is defined as a neoplastic process when there are blasts more than 20% in the peripheral blood or bone marrow. The blasts may be less than 20% in acute erythroblastic leukaemia. Acute erythroblastic leukaemia is classified as AML-M6.
A 4-month-old child was brought by the mother to the paediatric ward of Goa Medical College with the chief complaint of abdominal distension in the past 7 days. There was no history of fever or any drug intake. On general examination, the patient appeared pale, and there was no icterus or lymphadenopathy noted.
On systemic examination, the neurological examination was normal. The patient was conscious and alert. Abdominal examination revealed the liver was 4 centimetres below the right costal margin, firm, non-tender, and with a smooth surface. The spleen was 6 centimetres below the left costal margin, firm, extending up to umbilicus. No free fluid was noted.
Complete haemogram revealed haemoglobin 7 gm/dL (gram per decilitre), total white blood cell count 1,13,700 cells/mm3, red blood cell count 2.46 x 1012/L, packed cell volume (PCV) 15.9%, platelet count 2,50,000/mm3, mean corpuscular volume (MCV) 64 femtolitres (fL), mean corpuscular haemoglobin (MCH) 28 picograms (pg) per cell, mean corpuscular haemoglobin concentration(MCHC) 44 g/dL. The differential count (DC) showed erythroid cells 75, blasts- 05, myelocytes- 02, metamyelocyte- 04, neutrophils- 11, eosinophils- 03.
Peripheral smear showed mild hypochromia, mild anisocytosis, moderate poikilocytosis, marked polychromasia, and adequate platelets. Many of the erythroid cells showed megaloblastoid change (Figure 1) with some showing binucleation (Figure 2). Special staining using Periodic Acid Schiff (PAS) stain was done which demonstrated coarse granules in the cytoplasm of the erythroblasts (Figure 3).
Bone marrow aspiration was done which revealed hypercellular marrow. There was hyperplasia of erythroid series with a prominent shift to the left with some of them showing megaloblastoid forms, nuclear budding, binucleated and multinucleated forms and cytoplasmic vacuolization. The myeloid series showed presence of myeloblasts with some of them showing presence of Auer rods. The megakaryocytic series also showed dysplasia with some showing hypolobation and abnormal size (micromegakaryoblasts).
Thus, the diagnosis of erythroleukemia AML-M6 (FAB classification) was made.
Erythroleukemia (AML-M6) is a rare type of leukaemia belonging to the spectrum of AML. Giovanni Di Guglielmo first described erythroleukemia in the early twentieth century, and the disorder is often referred to as Acute di Guglielmo Syndrome.
It is further subclassified into:
AML M6 A
The criteria for diagnosis are:
Erythroblasts >50% of the bone marrow nucleated cells
Blasts >20% of bone marrow non-erythroid cells.
AML M6 B
This is a variant of M6 in which the malignant cells are the early proerythroblasts which are present as >80% of the marrow cells.
AML M6 C
In this rare type of erythroleukemia, blasts are >30% of the non-erythroid cells and erythroblasts are >30%. The erythroid component is a prominent feature of AML M6. The erythroblasts demonstrate bizarre megaloblastic/macronormoblastic reaction, nuclear cytoplasmic asynchrony, binuclearity, karyorrhexis and very few giant and multinucleated erythroblasts in a hyperplastic bone marrow. There may be presence of cytoplasmic vacuoles as well.
Can occur at any age. Most of the patients present with profound anaemia. Patients present with history of infections and easy bruising. Splenomegaly of variable degree may be present.
Bone marrow histology:
Trephine biopsy is hypercellular with prominent erythroid component and demonstrating megaloblasts, irregular and bizarre nuclei and lack of erythroid colonies. Scattered amongst the erythroid precursors are blast cells.
In AML M6A, CD71/CD117 and glycophorinA are expressed weakly on leukemic erythroblasts. The blasts of myeloid component are dim positive with CD31/CD33. In AML M6B, blasts are characterised by expression of glycophorin A, haemoglobin A and absence of myelopeoroxidase (MPO).
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