Thalassaemia intermedia is characterized by inefficient red blood cell production (erythropoiesis) and has a wide range of clinical symptoms. Splenectomy, often performed to manage complications, can lead to significant long-term changes in blood cell composition. This case illustrates a striking example of extreme normoblastosis in a patient two decades after a splenectomy. The case also underscores the critical role of flow cytometry in diagnosing blood disorders and differentiating abnormal findings from potential malignancies.

A 45-year-old woman with thalassaemia intermedia, who had her spleen removed at age 25, presented with severe anaemia, iron overload, and an unusually high normoblast count ranging from 50,000 to 100,000 cells/µL, as seen in a routine complete blood count (CBC). The CBC mistakenly identified the normoblasts as white blood cells, raising concern for possible blood cancer. Closer analysis of the CBC sub-parameters revealed an increased nucleated red blood cell (NRBC) ratio. Further investigation through bone marrow biopsy and flow cytometry was undertaken to rule out malignancy and better understand the extreme normoblastosis.

The diagnostic process involved multiple stages of flow cytometric analysis. First, a chronic lymphocytic leukaemia (CLL) panel was employed, followed by an acute leukaemia panel. Finally, a specialized flow cytometry panel targeting markers such as CD45, CD71, CD41, CD235a, CD19, CD10, CD13, HLA DR, CD36, CD38, and CD117 was used. The gating strategy focused on differentiating erythroid precursor cells based on their size, granularity, and marker expression.

Flow cytometry identified a significantly elevated population of normoblasts, with these cells displaying low CD45 expression and reduced side scatter. They tested weakly positive for CD71, strongly positive for CD36, and negative for CD235a, confirming their identity as erythroid precursors. Around 70% of the nucleated cells consisted of these normoblasts, representing various stages of erythroid maturation. The absence of lymphoid markers (CD19, CD10, CD5) ruled out lymphoid malignancies, while the exclusion of myeloid malignancies was confirmed through negative results for markers such as CD13, CD33, CD34, CD117, and HLA DR.

This case highlights the occurrence of extreme normoblastosis in a post-splenectomy patient and the challenges in managing such cases. It demonstrated that flow cytometry is essential for accurately identifying erythroid precursors, preventing a misdiagnosis of malignancy based solely on CBC results. The findings underscore the value of flow cytometry in evaluating complex haematological conditions, especially in patients with thalassaemia intermedia after splenectomy. Additionally, the strategic order of tests in the flow cytometry lab, along with collaboration between laboratory and clinical teams, was key to achieving a correct diagnosis. This case reinforces the need for a tailored flow cytometric testing algorithm for complex cases.