Myelodysplastic Syndromes: Essential Diagnostic Tests and Laboratory Evaluations

Diagnosing Myelodysplastic Syndromes (MDS) requires a comprehensive approach that combines multiple laboratory techniques, with bone marrow aspiration and cytogenetic analysis serving as the cornerstone of accurate identification. These tests are critical in detecting abnormal blood cell development, assessing blast cell percentages, and evaluating the presence of ring sideroblasts—key indicators that help confirm an MDS diagnosis.

Core Diagnostic Procedures for MDS

The primary diagnostic tool for suspected MDS is bone marrow aspiration, which allows hematologists to examine cell morphology under the microscope. This procedure focuses on identifying dysplasia in one or more blood cell lineages—red blood cells, white blood cells, and platelets. According to WHO criteria, significant dysplasia is typically defined as morphological abnormalities present in at least 10% of cells within a given lineage, providing strong evidence supporting an MDS diagnosis.

Bone Marrow Biopsy: Assessing Cellular Architecture

In addition to aspiration, a bone marrow biopsy is essential for all patients with suspected MDS. This procedure provides crucial information about overall cellularity, spatial organization of hematopoietic cells, and structural changes within the marrow. The sample is usually collected from the posterior iliac crest and should be at least 1.5 cm in length to ensure adequate tissue for evaluation.

Pathologists use special staining techniques during biopsy analysis, including CD34 immunohistochemistry to identify immature progenitor cells, reticulin staining to assess fibrosis levels, and specific stains for megakaryocytes to detect abnormal clustering or morphology—common features in MDS subtypes.

Cytogenetic Analysis: Unlocking Genetic Clues

Cytogenetic testing plays a pivotal role in both diagnosing and risk-stratifying MDS patients. Chromosomal karyotyping using G-banding or R-banding techniques enables clinicians to detect numerical and large-scale structural chromosomal abnormalities across the genome. Approximately 40% to 60% of MDS patients exhibit non-random chromosomal aberrations, such as deletions in chromosome 5q, 7q, or trisomy 8, which carry important prognostic and therapeutic implications.

These genetic findings not only support the diagnosis but also guide treatment decisions, including eligibility for targeted therapies or stem cell transplantation. In cases where standard karyotyping yields normal results but clinical suspicion remains high, advanced molecular testing like fluorescence in situ hybridization (FISH) or next-generation sequencing (NGS) may be employed to uncover hidden mutations in genes commonly associated with MDS, such as TET2, ASXL1, or SF3B1.

Together, these integrated diagnostic methods—morphological assessment, histopathology, and genetic profiling—form a robust framework for accurately identifying myelodysplastic syndromes, enabling early intervention and personalized patient management strategies.