Fig. 1

Morphologic study of the reported tumors. a. Left nephrectomy from the proband. Top: Gross morphology image of the resected kidney presenting a thin-wall multicystic parenchyma. Middle: Medium power view of a haematoxylin and eosin staining (HE) showing multiple cysts of different size. Scarce renal tissue is preserved. Bottom: Higher power view of the cysts surface showing a single layer of flattened/cuboidal cells with well oriented nuclei, acidophilus cytoplasm, and without atypia. b. Left lower lobectomy from the proband. Top: Gross morphology image of the resected lobe. An arrow is pointing to the cystic lesion of 12 mm largest size. Middle: At histological level, a unique benign cystic lesion was identified (HE). Bottom left: A single cubic-cell layer lining the epithelium was observed in most of the cystic lesion. Bottom right: Only very few and isolated clumps of primitive mesenchymal cells and small clusters of cells with rhabdomyomatous differentiation were found along the whole tissue sample. c. Histological images of the rhabdomyosarcoma from the proband’s cousin. Top: HE staining showing dense neoplastic cell proliferation in a solid-storiform pattern. Bottom: Intense pleomorphism is observed, with fusiform-oval cells and common mitotic figures, with focal anaplastic cells