Background: Malignant rhabdoid tumor (MRT) of the kidney is a rare and aggressive neoplasm with a controversial histogenesis. Although their immunohistochemistry may be diverse, the rhabdoid phenotype and mutations of the INI1 gene are consistently exhibited by MRTs regardless of their location.
Case: MRT recurred in the contralateral kidney in a 12-month-old child within 6 months after the initial histologic diagnosis, nephrectomy and autologous stem cell transplant. The presence of widespread metastases at the time of the recurrence precluded any further chemical and surgical diagnostic or therapeutic intervention.
Conclusion: To the best of our knowledge, only a few cases describing the cytologic diagnosis of MRT of the kidney in a child have been reported. This case illustrates the usefulness of cytologic diagnosis in an MRT recurrence.