Human pathology
-
Case Reports
Tumor progression in DICER1-mutated cystic nephroma-witnessing the genesis of anaplastic sarcoma of the kidney.
We report a 7-month-old female infant with a multicystic left renal tumor having histologic features predominantly of a cystic nephroma, but with microscopic cellular foci which contained atypical mitotic figures and anaplastic nuclei. Immunohistochemistry showed strong p53 reactivity in the anaplastic region. ⋯ Moreover, the germ line DICER1 mutation prompted consideration that this case represents a unique "nascent" anaplastic sarcoma of kidney, and further immunohistochemical workup demonstrated cytoplasmic, but no nuclear WT-1 reactivity in the cellular foci. The importance of meticulous sampling of cystic lesions is highlighted by this unprecedented case, which lends support to the recent recognition of anaplastic sarcoma of kidney as a DICER1-associated cancer.