Case Presentation: A 59 year old man presented to the ER with shortness of breath, non-productive cough and fever of 103○F. He was also being followed for an enlarging left tricep mass that has grown significantly in size for the past 2 months, currently at 11cm in diameter. CBC now revealed a WBC count of 86,000/µL with absolute eosinophil count of 57,620/µL. CT chest revealed diffuse patchy central ground glass opacities with focal areas of consolidation. Basic infectious work up was again negative, including sputum and blood cultures and HIV. Flow cytometry and bone marrow biopsy were negative for primary leukemia. FGFR1, JAK2 and F1P1L1 testing for primary hypereosinophilic syndrome were also unrevealing. Pathology mass revealed a pleomorphic high grade malignant fibrous histiocytoma. He was diagnosed with eosinophilic leukemoid reaction as a paraneoplastic manifestion from the malignant tumor. While awaiting surgical resection, he was given high dose prednisone to decrease the eosinophilia, along with naproxen for the recurrent fevers. Surgical resection of the sarcoma was performed and 2 days later and his WBC count decreased to 11,000/µL with an absolute eosinophil count of 3600/µL. Post-surgery the eosinophilia has not recurred. During admission, CT Chest also revealed an aortic root aneurysm with elevated troponin. The patient has been doing well, though his aortic aneurysm has enlarged with time and now requires repair.
Discussion: Hypereosinophilia is defined as moderate to severe eosinophilia (greater than 1500 eosinophils/µL). The mechanism of hypereosinophilia of malignant disease is poorly understood. Though the association of hematologic malignancies is stronger, solid tumors such as lung, breast and ovarian cancer has also been described to have an association. The association of eosinophilia with sarcomas is very rare, with only a few cases reported in the literature.
The proposed mechanism of hypereosinophilia with soft tissue sarcomas is by a paraneoplastic or reactive process due to release of cytokines (IL-6, IL-3, IL-5 and GM-CSF) from tumor cells (8). IL-3 and GM-CSF may have activity from other cells lines, however, IL-5 is most specific for eosinophils. It is unclear if eosinophilia is a good or a poor prognostic sign in the context of malignancy, though its long-term complications are well-known and described. It is generally suggested that the treatment of such cases should be the treatment of the underlying disorders. If there is an unidentified etiology of the hypereosinophilia, a search for underlying malignancy should be pursued. Treatment ultimately consists of tumor resection, where possible, or immunosupression. Frequent follow-up is recommended, particularly in the first two years after treatment, since more than 80 percent of recurrences will be detected during this period.
Conclusions: This case demonstrates that hypereosinophila may be associated with solid tumors and may precede, even be a clue to, the diagnosis. The production and survival of eosinophils are mainly regulated by IL-3, IL-5 and GM-CSF. Treatment of the underlying malignancy can reverse the eosinophilia and curb the development of long-term complications which stem from fibrosis. Despire the rare occurrence of eosinophilia or neutrophilia with malignancy, patients who have either, with no apparent cause, should be screened for malignancy. The management approach for eosinophilia due to malignancy is to treat the underlying disease.