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Also named "sinus
histiocytosis with massive lymphadenopathy", unknown etiology.
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Clinical
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Common in young males,
mean age 20.6 years, African-Americans.
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Leukocytosis, moderate
polyclonal hypergammaglobulinemia in most cases.
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Mostly in cervical LNs,
can involve other LNs or extranodal.
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Painless strikingly
enlarged LN.
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Spontaneous remission in
majority
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Histology:
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Thickened capsule and relatively
preserved architecture of the lymph node.
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Marked sinus expansion
filled with lymphocytes, plasma cells, and histiocytes.
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SHML cells: large and
irregularly shaped, abundant acidophilic vacuolated
cytoplasm, one nucleus, a central nucleolus.
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Emperipolesis: The
intracytoplasmic vacuoles of SHML cells contain engulfed
cells, as many as 20 cells, usually lymphocytes, plasma
cells, or erythrocytes. The engulfed cells are usually
contained in an intracytoplasmic vacuole. Some cells,
particularly lymphocytes in the vacuoles, are viable; others
are degraded, often forming nuclear fragments.
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Lack of mitoses or necrosis.
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IPX: CD14+,
CD68+, HLA-DR+, S100+, CD1a-.
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DDX:
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Sinus histiocytosis: no
lymphophagocytosis, S100-.
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ALCL: atypia, T-cell origin, CD30+,
S100-.
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LCH: nuclear grooves, eosinophilia,
S100+ and CD1a+.
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