A 62-year-old woman presented with severe leukocytosis and systemic symptoms including fatigue, low appetite, and weight loss. After 4 months of evaluation by doctors with extensive laboratory tests and imaging studies, a soft tissue sarcoma in the left posterior distal thigh was revealed. Quickly after surgical excision of the soft tissue sarcoma, the leukocytosis and systemic symptoms were dramatically resolved.
Leukemoid reaction can present as a paraneoplastic syndrome. Awareness of soft tissue sarcoma as a possible cause of leukemoid reaction may help improve the early diagnosis and subsequent early intervention in future cases.