1. ZHIHONG HU, MD, PhD Fellow, Department of Hematopahtology
The University of Texas
MD Anderson Cancer center

2. CLINICAL HISTORY
A 25-year-old man diagnosed with rheumatoid arthritis for the past 3 years
On follow-up of a repeat CBC, significant leukocytosis with eosinophilia about 6 months
Had an extensive workup done: negative for ova and parasites, strongyloids
A bone marrow biopsy was completely negative, negative for BCR-ABL, JAK2 , PDGFR alpha and beta
Echocardiogram was negative

3. CLINICAL HISTORY (cont’d)
For his RA, treated with methotrexate
Switched to leflunomide for the past month due to intolerance to methotrexate
Not much complaints, except for two nodules on the right leg, and other symptoms secondary to RA (joint stiffness and swelling (small joints of his hands, elbows and wrists) in the morning that lasts more than 1 hour, which is consistent with his RA
No good reason for his underlying eosinophilia other than his rheumatoid arthritis

4. ANCILLARY STUDIES CBC: WBC 38.2K/mL H (4.0-11.0)
RBC 4.50M/mL ( )
Hgb 13.9gm/dL L ( )
Neutrophil: 22.0% L ( ); 8.40K/mL H ( ),
Lymphocyte:15.0% L( ); 5.73K/mL H ( )
Monocyte: 2.0% ( ); 0.76K/mL H ( ),
Eosinophil: 61.0% H ( ); 23.30K/mL H ( )
Sodium 139, potassium 4.4, chloride 104, bicarb 28, BUN 7, creatinine 0.84, glucose 47

5. PERIPHERAL BLOOD SMEAR

6. BONE MARROW BIOPSY

11. PROPOSED DIAGNOSIS
Cellular (80%) bone marrow with trilineage hematopoiesis and marked eosinophilia, compatible with LYMPHOCYTE VARIANT OF HYPEREOSINOPHILIC SYNDROME
Sub-diagnostic systemic mastocytosis

12. TAKE HOME MASSAGE
Aberrant T cell population of CD3-CD4+ immunophenotype is seen in the lymphoid variant of hypereosinophilic syndrome (L-HES)
Monoclonal TCR gamma gene arrangement can be detected in L-HES
Sub-diagnostic systemic mastocytosis: those meeting 1-2 minor criteria for SM only