PDGFRᵝ-Rearranged Myeloid Neoplasm with Marked Eosinophilia in a 37-Year-Old Man; And a Literature Review.

BACKGROUND PDGFRᵝ-positive myeloid neoplasms are rare. Marked leukocytosis (over 100×10⁹/L) with marked eosinophilia (over 10%) has been rarely described in myeloid neoplasms associated with PDGFRᵝ rearrangement. CASE REPORT We report a case of 37-year-old man with myeloid neoplasm associated with PDGFRᵝ rearrangement who presented with marked eosinophilia of 13.3% and leukocytosis with WBC count of 189×10⁹/L. He was found to have PDGFRᵝ locus rearrangement at 5q32-33 by fluorescent in situ hybridization (FISH). He responded very well to low-dose imatinib therapy. To the best of our knowledge this degree of hypereosinophilia and leukocytosis in a young adult was reported only once previously. Using low dose therapy in treating this condition has rarely been reported and has not been clearly defined. Our case demonstrated that low dose imatinib therapy can be as effective as high dose imatinib therapy in treating PDGFRᵝ-positive myeloid neoplasms. CONCLUSIONS The patient presented with very high WBC and eosinophil count rarely reported in a young adult with PDGFRᵝ-rearranged myeloid neoplasm. The recognition of this rare presentation as a manifestation of PDGFRᵝ-gene translocation is important, and equally important that low-dose imatinib (100 mg/day) might have the same effect as higher dose imatinib (400 mg/day).