Introduction
Hypereosinophilia can be seen in many medical conditions, including myeloproliferative disorders, and can lead to serious complications if untreated. Sweet syndrome is a rare and painful cutaneous inflammatory condition that has been linked to underlying malignancies.
Case Presentation
A 72-year-old male presented with 6-month history of painful maculopapular rash, night sweats, fever, and weight loss. He was treated with antibiotics and steroids with no improvement. A skin biopsy demonstrated neutrophilic dermatosis consistent with sweet syndrome. Laboratory studies a showed hemoglobin 7.1g/dl, WBC 12.9x103/uL, 30% eosinophils, absolute eosinophil count 3x109/L, and normal platelets. Infectious and immunological work up was negative. CT scan revealed splenomegaly. Bone marrow biopsy showed 100% hypercellularity, trilineage atypia, eosinophils 43% (normal, 1-5%) and 3-4% blasts positive for CD34 and CD117. FISH studies detected loss of PDGFRB signal, cytogenetics revealed a complex karyotype. He was diagnosed with a high-risk (based on IPSS-R) MDS/MPN cross-over with peripheral eosinophilia and is planned to undergo HSCT.
Discussion
Hematologic malignancies are associated with several paraneoplastic syndromes including sweet syndrome, also known as acute febrile neutrophilic dermatosis. The literature describes sweet syndrome occurring mostly with AML but can also be seen with other malignancies like MDS and solid tumor. The distinction between sweet syndrome and infectious or immune-mediated rash can be challenging as it requires histopathologic evaluation and is usually mistreated. Hypereosinophilia is defined as persistent eosinophil count of at least 1.5x109/L. It can be idiopathic or associated with allergic, rheumatologic, infectious, or neoplastic conditions. Clonal hypereosinophilia is most frequently associated with chronic myeloid neoplasms such as myeloproliferative neoplasm (MPN) or overlapping MDS/MPN, and more less frequently with AML. Hypereosinophilia related to hematological malignancies has been linked to gene rearrangements involving PDGFRA, PDGFRB, FGFR1, and JAK2. Patients with documented rearrangements or mutations in PDGFRB are treated with imatinib, which is a potent kinase inhibitor. However, patients with high-risk MDS/MPN with associated eosinophilia are typically treated as MDS and should undergo allogenic HSCT if eligible.
Conclusions
Both hypereosinophlia and sweet syndrome have been linked to myeloid neoplasms. Early recognition of either phenomenon as a paraneoplastic syndrome is important for early diagnosis and treatment.
