Case Report: Two cases of secondary malignant neoplasms following treatment in pediatric patients.

Among the various long-term iatrogenic sequelae associated with the treatment of pediatric and adolescent patients with malignancies, secondary malignant neoplasms (SMNs) are among the greatest concerns. Chemotherapeutic agents may increase the risk of SMNs. We present the first case of a patient initially diagnosed with T-cell acute lymphoblastic leukemia (T-ALL), who received 30 months of chemotherapy, including the alkylating agent cyclophosphamide, the topoisomerase II inhibitor daunorubicin, and subsequently developed cervical anaplastic large cell lymphoma (ALCL) three years after the initial diagnosis. We also present the second case of a patient initially diagnosed with clear cell sarcoma of the kidney (CCSK), who underwent 6 months of chemotherapy, including the alkylating agent cyclophosphamide, the topoisomerase II inhibitors etoposide and pirarubicin, together with 3 months of radiotherapy, and subsequently developed Ewing sarcoma of the lower leg five years after the initial diagnosis. The cases reported in this study expand the spectrum of reported SMNs following treatment and provide pathologists with additional references for establishing pathological diagnoses on the basis of patients' medical histories and prior treatment regimens.