Guided Case: Rank the Evidence

The case has persistent multilineage cytopenia and macrocytosis, with concerning peripheral smear features. An adequate marrow aspirate reports 3% blasts, erythroid dysplasia about 18%, and granulocytic dysplasia about 12%. The marrow iron stain has 18% ring sideroblasts. These are directly observed marrow findings; their classification meaning requires the mutation and exclusion context.

Ancillary studies show 46,XX,del(5)(q31q33)[12]/46,XX[8] and SF3B1 p.K700E with variant allele frequency 32%, with no TP53 variant detected. del(5q) means a clonal chromosome copy has lost material from the long arm (q) of chromosome 5. SF3B1 is a gene involved in RNA splicing; a qualifying mutation plus at least 5% ring sideroblasts supports the SF3B1 pathway in the applicable classification. This case has SF3B1 mutation plus 18% ring sideroblasts. If SF3B1 mutation is absent, 15% ring sideroblasts is the alternate morphologic threshold used for the ring-sideroblast pathway; it is not needed to make the mutation-plus-ring-sideroblast connection in this case.

The worksheet supports an MDS workup, not a released disease subtype. Document vitamin B12, folate, copper, medication and toxin history, alcohol exposure, infection, and autoimmune context before qualified review applies the current controlled classification procedure. The marrow report should include adequacy, hemodilution if present, cellularity, blast method and denominator, dysplasia lineages and estimated percentages, iron-stain result, cytogenetic result, molecular result, and material limitations.