Sea blue histiocytes (SBH) may be identified in the bone marrow of patients with a variety of different conditions, especially when the marrow is hypercellular.
Features of the sea blue histiocytes:
(1) increased cytoplasm with coarse, basophilic granules
(2) small nucleus
(3) The granules stain with Sudan black and periodic acid Schiff (PAS) stains.
Conditions associated with sea blue histiocytes:
(1) Niemann Pick disease
(2) Hurler disease or other storage disorders
(3) chronic myelogenous leukemia or other chronic myeloproliferative disorder
