Bone marrow biopsy showed a marrow filled with mononuclear cells with a high apoptotic rate. Immunohistochemistry was negative for chromogrannin, CD99, NSE, and CD20 but positive for leukocyte common antigen. Monoblastic markers including lysozyme and CD68 were also positive supporting a diagnosis of congenital acute monoblastic leukemia. Post-mortem examonation revealed leukemic infiltrates in many organs most notably the skin, adrenal glands, pancreas, liver, and kidney.
There is a dense dermal and subcutaneous infiltrate of pleomorphic cells varying in size and and nuclear configuration. Larger cells show vesicular nuclei and smaller cells contain folded or cleaved nuclei (see arrow).