Eosinophilia and monoclonal spike, consider clonal lymphocytic variant HES

Question:

9/11/2017
I saw a 62 year-old male with history of long standing eosinophilia dating back to 11-2013 when WBC count was 13,400 with eosinophil count of 4100. In 5-2016, WBC count was 13,900 with eosinophils count of 4600 and 15,400 and 6000 about 1 week later. In 1-2017, WBC count was 23,300 and eosinophil count was 10,700. In 2-2017, WBC count was 16,600 and eosinophil count was 2100. He continues to have persistent eosinophilia with WBC count of 14,000 and eosinophils of 4900 in 4/2017. He was also seen by hematology. Atypical eosinophilic forms were not seen on peripheral smear. Workup has included normal tryptase, negative stool ova and parasite studies, and negative BCR-ABL oncogene study. CT chest/ abdomen/pelvis was unremarkable and did not reveal any cause for eosinophilia or leukocytosis. Bone marrow biopsy showed orderly maturations with 15% eosinophils and low iron storage only. Chromosome studies showed normal karotype. C-kit mutation was not detected. Findings do not suggest mastocytosis, myeloproliferative disorder, or hematologic malignancy. He has not travelled outside of the country and has not been in the army, navy, or marines. He had elevated IgG at 2130 and IgE at 1760. Immunofixation showed Monoclonal IgG-Kappa chains. His medications include Tylenol as needed, amantadine, aspirin, lipitor, plavix, lisinopril, melatonin, senna, zoloft, and mutivitamin. He does not take any herbal medications or other supplements. He does not have a history of frequent prednisone use. Additionally ESR was 26, CRP was 5.3 and CMP was in normal limits.

He does not experience any symptoms of cardiac end organ damage, but has not had an echo done as of yet. He does have a history of stroke in 5/2016 as well as 11/2016. However, he has cerebrovascular risk factors of hypertension and hyperlipidemia and had significant ICA occlusion which could have contributed to his watershed infarcts.

He has mild eczema on his legs and hands which is controlled and rhinitis symptoms of runny nose and sneezing only which are mild. Otherwise he does not have a significant atopic history.

I am planning to check strongyloides antibodies as well as some additional parasites. What additional workup may be helpful in finding the cause and treatment for his eosinophilia?