Question: 20210002




#1:   Multiple primaries
#2:   Heme & Lymphoid Neoplasms


Source 1:   Heme & Lymphoid Manual and Database
Notes:   September 2020; Effective with Cases Diagnosed 1/1/2010 and Forward
Source 2:   WHO Class Heme and Lympoid Neoplasms
Notes:   4th edition, online version


Multiple Primaries--Heme & Lymphoid Neoplasms: How many primaries are accessioned for a patient diagnosed with therapy-related myelodysplastic syndrome (t-MDS) (9920/3) in 2015 followed by a 2020 diagnosis of myelodysplastic syndrome, NOS (MDS, NOS) (9989/3)? See Discussion.


Patient has a history of B-cell lymphoma with multimodality treatment in 2002. Lab work in 2015 showed multilineage dysplasia leading to a diagnosis of therapy-related myelodysplastic syndrome. Patient presents in 2020 for a bone marrow biopsy now showing low-grade MDS. The MDS appears to have the same multilineage dysplasia previously identified.

MDS, NOS is not listed in the Heme DB as a possible transformation of t-MDS, nor is it listed as a Same Primary for t-MDS. Likewise, t-MDS is not listed as a more specific myelodysplastic syndrome, a transformation of MDS NOS, or a Same Primary as MDS, NOS.

The first M rule that applies to this case is M15, and the Multiple Primaries Calculator indicates that the MDS, NOS should be a new primary.


Abstract separate primaries using Rule M15 of the Hematopoietic and Lymphoid Neoplasms (Heme) Manual.  The Heme Database states:  Excluded from this category are progression of myeloproliferative neoplasms (MPNs) and evolution of primary MDS or primary MDS/MPN to acute myeloid leukemia (AML); in each of these latter cases evolution to AML is part of the natural history of the primary disease and it may be impossible to distinguish natural progression from therapy-related changes.  There is no indication of transformation.


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