Easily visible diffuse BM infiltration by storage-type histiocytes with abundant foamy, crinkled, granular blue (Giemsa staining) or PAS+ cytoplasms is the hallmark of lysosomal storage diseases.  
 
1. Thus, may I ask that you add staining results of a Giemsa and PAS stain?  
 
These are rare genetic, mostly autosomal recessive inherited enzymopathies leading to systemic accumulation of respective enzyme substrates (lipids, proteins) that cannot be metabolized in the phagolysosomes.  
 
2. Thus, may I ask for the family history of the patient?  
 
In addition to the histiocytic lineage, lymphocytes can also appear abnormally vacuolated, especially on smears.  
 
3. Is this the case in this patient?  
 
Despite the fact that such patients mainly suffer from systemic manifestations and the diagnosis is almost always suspect prior to BM examination, only occasionally the clinical course may be a-/oligosymptomatic and the respective disease may be detected as an incidental finding.  
 
4. Is this the case in this patient? Does she have other findings suggestive of a storage disease, e.g. organomegaly?  
 
Extensive pale to eosinophilic (HE staining) BM infiltration by cytoplasm-rich histiocytes that appear basophilic/bluish and striated on Giemsa stained slides and are PAS+ is the hallmark of Gaucher disease (please add a respective staining). Foamy macrophages with uniform vacuoles and slight PAS positivity are characteristic, yet not specific of Niemann-Pick disease and sialidosis (lease add a respective staining). Sea-blue histiocytosis, also known as inherited lipemic splenomegaly, is extremely rare and is so named because histiocytes appear bright blue and packed with coarse basophilic granules in the Giemsa stain.  
 
Importantly, morphologically identical cells to those described above, yet usually less abundant, can be observed in various acquired disorders accompanied by increased cell turnover such as myelodysplastic- or myeloproliferative and myeloproliferative-myelodysplastic neoplasms, lymphomas, alimentation disturbances or dyslipidemic conditions such as Tanger disease as well as dissemainated mycobateriosis (6. please add a Ziehl-Neelsen stain) and are per se not diagnostic of a certain disease.  
 
For obvious reasons it cannot be overemphasized that establishing the diagnosis of a constitutional storage disorder may only be supported by but not based on a morphologic BM examination.  
 
A differential diagnosis to consider is Erdheim-Chester disease, an inflammatory myeloid neoplasm (with a distinctive radiological presentation) with foamy histiocytes and Touton giant cells (I am not able to see such in this case), involving, among other organs and systems, the skeleton (7. please ask the radiologists whether there are signs of Erdheim-Chester disease!) and thus the BM.  
 
To obtain a final diagnosis, you should address the 7 points above.  

thanks for the nice detailed feed back. We just got the triphen biopsy... I will contact patient and ask him the questions.

as far as the morphology tells, the infiltration is strongly suggestive of Gaucher disease.  
For the sake of treatment, an enzyme assay& if possible genetic study is required to start.  
Gaucher is not a rare disease in my region (Egypt& Middle East) with the childhood type the most frequent & much less the adult type. Cases with confirmed diagnosis& without neurologic involvement receive a Genzyme treatment with great results but very very expensive.