1. Annika Windon MD, Yusong Yang MD PhD, Leonas Bekeris MD, Adam Bagg MD
Crystal-storing histiocytosis: definite diagnostic difficulties associated with this marvelous masquerader masking malignant myeloma
Case #: EAHP16-BMWS-224
Annika Windon MD, Yusong Yang MD PhD, Leonas Bekeris MD, Adam Bagg MD

2. Clinical History 57-year-old male
Presented with a creatinine of 14 mg/dL in acute renal failure during an episode of severe diarrhea secondary to Clostridium difficile
Bone marrow showed peculiar inclusions in macrophages that were interpreted to be concerning for leishmaniasis
 slides submitted in consultation

3. Bone marrow aspirate smear, modified Wright-Giemsa (20x):
Expanded macrophage population with intracytoplasmic inclusions

4. Bone marrow aspirate smear, modified Wright-Giemsa (40x):
Macrophages contain abundant irregular purple intracytoplasmic inclusions

5. Bone marrow aspirate smear, modified Wright-Giemsa (100x):
Plasma cells contain similar irregular pinkish-purple intracytoplasmic inclusions

6. Aspirate clot, H&E (20x):
Cluster of macrophages with eosinophilic intracytoplasmic inclusions

7. Aspirate clot, H&E (50x):
Clusters of macrophages with intracytoplasmic crystals

8. Aspirate clot, H&E (100x):
Macrophages and plasma cells with intracytoplasmic crystals

9. Immunohistochemistry summary
Plasma cell expansion (20-30%)
CD79a+ CD138+ MUM1+ kappa-restricted
CD20- CD45- CD56- PAX5-
Macrophages
CD68+ CD163+ lysozyme+
Crystalline material within macrophages
Kappa+ CD138+

10. Aspirate clot, immunohistochemistry, lighter image (50x):
CD138 highlights plasma cells and inclusions in macrophages
Plasma cells:
Macrophages:

11. Aspirate clot, immunohistochemistry, darker image (40x):
CD138 highlights plasma cells and inclusions in macrophages
Plasma cells:
Macrophages:

12. Aspirate clot, immunohistochemistry (50x):
Plasma cells (brighter) and intracellular inclusions (dimmer) are kappa restricted
Kappa
Lambda

13. Additional Workup Laboratory Studies Radiology SPEP
Hypogammaglobulinemia, no monoclonal spike
Urine immunofixation
Free kappa light chains
Creatinine
2.3 mg/dL (Max:14 mg/ dL)
Radiology
X-ray
Focal lytic lesion of the distal shaft of the left humerus measuring 1.7 x 1.2 cm
Just need to add imaging

14. Cytogenetics Conventional cytogenetics FISH Normal male karyotype
Positive for t(11;14)/CCND1-IGH

15. Diagnosis
Crystal-storing histiocytosis

16. Interesting Features Diagnostic challenges Crystals are CD138+
Macrophages harboring crystalline material often mistaken for Gaucher cells or pseudo-Gaucher cells of CML
This case was thought to reflect leishmaniasis
The macrophages masked the underlying plasma cell neoplasm
Crystals are CD138+
Raises the possibility that the macrophages may be ingesting plasma cell fragments rather the protein
Prognosis
Typically poor, but this patient remains alive and well 4 years after presentation