Case Report: DICER1 mutation-associated anaplastic sarcoma of the kidney in a child

DICER1 syndrome is a hereditary tumor predisposition syndrome caused by pathogenic germline variants in DICER1 and is characterized by multi-organ susceptibility; sarcomas remain uncommon within this spectrum. We report a 2-year-old girl with anaplastic sarcoma of the kidney (ASK). Molecular testing identified a germline DICER1 c.3300dupA frameshift variant (p.S1101Ifs*3), inherited from her father, and a tumor-associated c.5125G>A missense variant (p.D1709N). The child had neonatal hypothyroidism and language developmental delay. She underwent complete tumor resection followed by 27 weeks of chemotherapy using a Stage I clear cell sarcoma of the kidney (CCSK)-based regimen. At the most recent follow-up, she was 3 years off therapy with no evidence of tumor recurrence or distant metastasis. This case adds to the limited clinicopathologic and molecular descriptions of DICER1-associated ASK and supports integrated histopathologic and molecular evaluation, familial DICER1 assessment, genetic counseling, and long-term syndrome-directed surveillance.