Myeloid Sarcoma : Immunophenotyping

Comments:
Immunohistochemistry and immunophenotyping by flow cytometry are crucial for accurate diagnosis of myeloid sarcoma. Flow cytometric analysis shows expression of CD13, CD33, CD117, and MPO in tumors with myeloid differentiation. Cases with monoblastic differentiation show CD14, CD163, and CD11c. There is generally absence of lineage specific B- and T-cell markers, although aberrant expression is found in some cases.

The image shows megakaryoblastic myeloid sarcoma presenting in the small intestine. Uniform cells with little cytoplasm form sheet-like growth effacing the normal architecture. Note the abundant megakaryoblasts. The tumor cells were positive for CD34, CD43, myeloperoxidase, and CD61 by immunohistochemistry.

Image courtesy of: The New York Pathological Society (@NYPathSociety); used with permission.