Remstein et al listed clinical and histologic features of a sclerosing extramedullary hematopoietic tumor (SEMHT). The authors are from the Mayo Clinic.


The patient has chronic myeloproliferative disorder, usually myelofibrosis. The diagnosis of SEMHT can be challenging if the diagnosis of a myeloproliferative disorder is not known.


Tumor locations may include:

(1) renal or perirenal

(2) mesentery

(3) omentum


The tumor shows:

(1) extramedullary hematopoiesis, often with large, atypical megakaryocytes

(2) a myxoid and/or collagenous/sclerotic stroma

(3) trapped fat


Supportive studies:

(1) The atypical megakaryocytes show positive immunostains for Factor VIII.

(2) Granulocyte precursors stain with myeloperoxidase.

(3) Erythroid precursors will stain for hemoglobin.


Differential diagnosis:

(1) myelolipoma

(2) lymphocyte depleted Hodgkin's disease

(3) sclerosing liposarcoma


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