Abstract
RATIONALE: Langerhans cell sarcoma (LCS) is a rare, high-grade neoplasm characterized by overtly malignant cytologic features and a poor prognosis. Herein, we present a rare case of langerhans cell histiocytosis (LCH) that later transformed into langerhans cell sarcoma 11 months after the benign mass was excised from soft tissue in the right groin. PATIENT CONCERNS: A 41-year-old patient who presented with a mass in the right groin for 3 years earlier after being bitten by ants. DIAGNOSES: The patient was diagnosed with langerhans cell sarcoma arising from antecedent langerhans cell histiocytosis. INTERVENTIONS: The patient underwent with 6 cycles of a modified etoposide, cyclophosphamide, vindesine, dexamethasone (E-CHOP) regimen. OUTCOMES: The patient is currently receiving follow-up care. LESSONS: LCH transformed into LCS is a rare case. E-CHOP as an effective first-line therapy to treat LCS cases, but, the mechanism is unclear. Due to their rarity, further data on clinical outcomes are necessary to establish the optimal treatment strategy for LCS.