MPN-092 Paraneoplastic Eosinophilia: An Unusual Initial Presentation of Metastatic Pancreatic Adenocarcinoma.

Paraneoplastic eosinophilia is mainly associated with hematologic malignancies. It has been reported in solid tumors through case reports. Among solid tumors, hypereosinophilia was mainly described in melanoma and lung, renal, and thyroid carcinomas. We report the case of a 58-year-old female patient, a previously healthy heavy smoker who presented with worsening abdominal pain and dyspnea. Laboratory tests revealed hypereosinophilia with an absolute eosinophilic count (AEC) of 65,000/mm3, thrombocytosis (platelets=890,000/mm3 ), and disturbed liver function tests. Chest-abdomen-pelvis CT scan showed a huge necrotic tumor in the tail of the pancreas associated with multiple regional and retroperitoneal lymph nodes, liver metastases, and multiple bilateral lung nodules with lymphangitic carcinomatosis. We performed the following laboratory tests to exclude different etiologies of eosinophilia: infectious diseases (mainly parasitic infections), connective tissue diseases, autoimmune disorders, and allergic causes (normal IgE levels). Bone marrow aspirate and biopsy did not show any evidence of bone marrow metastasis, and there was no leukemia nor myelo/lymphoproliferative disorder. Fluorescent in-situ hybridization did not detect a FIP1L1-PDGFRα fusion. After getting clearance from the infectious disease team (excluding any parasitic infection), a CT-guided liver biopsy was done and revealed the presence of adenocarcinoma cells compatible with primary pancreatic carcinoma. The patient was on oxygen and was started on dexamethasone for the hypereosinophilia. We initiated first-line chemotherapy for advanced pancreatic adenocarcinoma with gemcitabine and nab-paclitaxel. After the first cycle, the patient was off oxygen with near resolution of the hypereosinophilia (AEC=900/mm3 ). She received 8 cycles of gemcitabine and nab-paclitaxel. Then, she progressed with worsening lymph node metastases but without any re-increase in AEC. She received second-line treatment with mFOLFIRINOX for 12 cycles. Thereafter, she progressed with peritoneal carcinomatosis and liver metastases. Her condition deteriorated until she passed away. Paraneoplastic eosinophilia has been rarely reported in advanced pancreatic adenocarcinoma. It is characterized by a more aggressive disease and dismal outcome. Clinicians must be aware of this condition and must exclude all other causes of hypereosinophilia before making this diagnosis.