Case 1121 - A Man in His 60s with Essential Thrombocythemia and a Rising Lactate Dehydrogenase

Authors: Rachel Vanderschelden, MD; Nathanael Bailey, MD

Clinical History

The patient is a man in his early 60s with a past medical history of essential thrombocythemia, diagnosed on bone marrow biopsy 20 years prior, at age 42. He had been treated with anagrelide and aspirin without complications. The patient presented to his hematologist for routine bloodwork; and was found to have mildly elevated white blood cell count of 11.1, with a differential showing 2% blasts, 4% myelocytes, and 4% metamyelocytes. Additionally, he had an LDH of 679 IU/L (normal: <171 IU/L).

Peripheral smear demonstrated the following:

Image 1
A. H&E, 1000x: a normoblast and several teardrop cells. B. H&E, 1000x: an immature myeloid cell and several teardrop cells.

 A bone marrow biopsy was performed, which demonstrated the following:

Image 2
A. H&E, 100x and B. H&E, 1000x: Sections showed markedly fibrotic bone marrow (MF-3) with cellularity ranging from 10-50%. Multiple clusters of atypical megakaryocytes were seen, some with small and hypolobate nuclei and others with bizarrely lobated hyperchromatic nuclei.

Diagnosis and Discussion