Case Report: Metastatic Dedifferentiated Liposarcoma Presenting as Hypereosinophilia in an Adolescent.

Soft-tissue sarcomas associated with eosinophilia are rare, with limited cases reported in adults, and even fewer in the pediatric population. In this report, we highlight the importance of malignancy in the differential of hypereosinophilia in an adolescent. A 17-year-old boy presented with incidental findings of multiple bilateral pulmonary nodules on chest computed tomography (CT), and hypereosinophilia (absolute eosinophilic count [AEC] 7029 cells/mm, hypereosinophilia defined as AEC >1500 cells/mm). Lung biopsy showed high-grade metastatic sarcoma. A positron emission tomography-computed tomography (PET-CT) demonstrated a 7.9-cm mass in the left thigh, with biopsy revealing dedifferentiated liposarcoma. Subsequently, the patient was diagnosed with liposarcoma, with lung, mediastinal, and brain metastases. He completed six cycles of ifosfamide/doxorubicin, followed by surgical resection of primary thigh tumor and brain lesion. Given widely metastatic disease, he received palliative chemotherapy, and later transitioned to hospice. The patient died of respiratory failure from malignant pleural effusions. In conclusion, this case demonstrates the importance of a having a broad differential for hypereosinophilia, including malignancy, to expedite the diagnosis and initiate appropriate management promptly.