Changes

==Definition / Description of Disease==

==Definition / Description of Disease==

Waldenström macroglobulinemia (WM) is a clinicopathological entity characterized by presence of [[Lymphoplasmacytic Lymphoma|Lymphoplasmacytic lymphoma]] (LPL) associated with any level of monoclonal immunoglobulin M (IgM) in the serum.

Waldenström macroglobulinemia (WM) is a clinicopathological entity characterized by presence of [[HAEM5:Lymphoplasmacytic lymphoma|Lymphoplasmacytic lymphoma]] (LPL) associated with any level of monoclonal immunoglobulin M (IgM) in the serum.

==Synonyms / Terminology==

==Synonyms / Terminology==

==Sites of Involvement==

==Sites of Involvement==

*By definition, diagnosis of Waldenström macroglobulinemia requires bone marrow involvement by [[Lymphoplasmacytic Lymphoma|Lymphoplasmacytic lymphoma]].

*By definition, diagnosis of Waldenström macroglobulinemia requires bone marrow involvement by [[HAEM5:Lymphoplasmacytic lymphoma|Lymphoplasmacytic lymphoma]].

*Lymphadenopathy and hepatosplenomegaly are more common at the time of relapse (up to 50%) rather than at the time of initial presentation (20%). <ref>{{Cite journal|last=Shaheen|first=Saad P.|last2=Talwalkar|first2=Sameer S.|last3=Lin|first3=Pei|last4=Medeiros|first4=L. Jeffrey|date=2012-01|title=Waldenström macroglobulinemia:  a review of the entity and its differential diagnosis|url=https://pubmed.ncbi.nlm.nih.gov/22156831|journal=Advances in Anatomic Pathology|volume=19|issue=1|pages=11–27|doi=10.1097/PAP.0b013e31824019d0|issn=1533-4031|pmid=22156831}}</ref>

*Lymphadenopathy and hepatosplenomegaly are more common at the time of relapse (up to 50%) rather than at the time of initial presentation (20%). <ref>{{Cite journal|last=Shaheen|first=Saad P.|last2=Talwalkar|first2=Sameer S.|last3=Lin|first3=Pei|last4=Medeiros|first4=L. Jeffrey|date=2012-01|title=Waldenström macroglobulinemia:  a review of the entity and its differential diagnosis|url=https://pubmed.ncbi.nlm.nih.gov/22156831|journal=Advances in Anatomic Pathology|volume=19|issue=1|pages=11–27|doi=10.1097/PAP.0b013e31824019d0|issn=1533-4031|pmid=22156831}}</ref>

*Peripheral blood may have lymphocytosis with small circulating neoplastic cells with condensed chromatin and inconspicuous nucleoli. Rouleaux formation is also observed. <ref name=":5" />

*Peripheral blood may have lymphocytosis with small circulating neoplastic cells with condensed chromatin and inconspicuous nucleoli. Rouleaux formation is also observed. <ref name=":5" />

==Morphologic Features==

==Morphologic Features==

*Bone marrow involvement by [[Lymphoplasmacytic Lymphoma|lymphoplasmacytic lymphoma]] is characterized by an interstitial, diffuse, or nodular patterns of infiltration. <ref name=":1" />

*Bone marrow involvement by [[HAEM5:Lymphoplasmacytic lymphoma|lymphoplasmacytic lymphoma]] is characterized by an interstitial, diffuse, or nodular patterns of infiltration. <ref name=":1" />

*Tumor burden of the bone marrow is variable with a wide range of percentage of involvement (5-95%). <ref name=":6" />

*Tumor burden of the bone marrow is variable with a wide range of percentage of involvement (5-95%). <ref name=":6" />

*Paratrabecular infiltration is composed of nodular aggregates or single cells along the bone trabeculae with peritrabecular fibrosis and is seen in 95% of cases. <ref name=":4">{{Cite journal|last=Bassarova|first=Assia|last2=Trøen|first2=Gunhild|last3=Spetalen|first3=Signe|last4=Micci|first4=Francesca|last5=Tierens|first5=Anne|last6=Delabie|first6=Jan|date=2015-06|title=Lymphoplasmacytic lymphoma and marginal zone lymphoma in the bone marrow: paratrabecular involvement as an important distinguishing feature|url=https://pubmed.ncbi.nlm.nih.gov/25972321|journal=American Journal of Clinical Pathology|volume=143|issue=6|pages=797–806|doi=10.1309/AJCP6ZODWV1CIDME|issn=1943-7722|pmid=25972321}}</ref>

*Paratrabecular infiltration is composed of nodular aggregates or single cells along the bone trabeculae with peritrabecular fibrosis and is seen in 95% of cases. <ref name=":4">{{Cite journal|last=Bassarova|first=Assia|last2=Trøen|first2=Gunhild|last3=Spetalen|first3=Signe|last4=Micci|first4=Francesca|last5=Tierens|first5=Anne|last6=Delabie|first6=Jan|date=2015-06|title=Lymphoplasmacytic lymphoma and marginal zone lymphoma in the bone marrow: paratrabecular involvement as an important distinguishing feature|url=https://pubmed.ncbi.nlm.nih.gov/25972321|journal=American Journal of Clinical Pathology|volume=143|issue=6|pages=797–806|doi=10.1309/AJCP6ZODWV1CIDME|issn=1943-7722|pmid=25972321}}</ref>