Cytopathology of uncommon malignant renal neoplasms in the pediatric age group

Abstract

Malignant renal neoplasms are common solid tumors in pediatric oncology practice. These include the common Wilms' tumor/nephroblastoma and the uncommon neoplasms such as clear-cell sarcoma of the kidney (CCSK), rhabdoid tumor, renal-cell carcinoma, and others. The aim of this study was to describe in detail the cytopathological features of the histopathologically proven uncommon pediatric renal tumors. Aspirates from Wilms' tumor, which are mesenchyme predominant, show clusters of spindle cells associated with the matrix material. Evidence of rhabdomyoblastic differentiation may be present. CCSK, classic subtype, is characterized by round to oval cells arranged perivascularly and also in sheets and clusters intimately associated with a metachromatic matrix mucopolysaccharide material better appreciated in May-Grunwald-Giemsa (MGG)-stained smears. The cells also have more abundant cytoplasm and may show nuclear grooves. Spindle-cell pattern of CCSK is difficult to diagnose on aspiration cytology. Renal-cell carcinoma of childhood shows similar cytological features as its adult counterpart. Rhabdoid tumor of the kidney is characterized by a monomorphic population of cells with abundant cytoplasm, eccentric nuclei with prominent nucleoli. Intrarenal yolk sac tumor is a rare neoplasm and shows severely pleomorphic cells on aspiration. Awareness of these entities is important for the practicing cytopathologist. Further, non-Wilms' renal malignant neoplasms must be distinguished from the common Wilms' tumor so that appropriate chemotherapy protocols may be instituted in cases where the tumor is in an advanced stage of malignancy.

Role of fine needle aspiration cytology in the management of pediatric renal tumors

“…Other rare pediatric renal tumors like clear cell sarcoma of kidney (CCSK) may be diagnosed prior to starting the chemotherapy. [7,8] Despite FNAC being a good evaluative technique, increasingly, trucut needle biopsy is being preferred, [9] owing largely to pathologists being unfamiliar with FNAC morphology and the ease of performing immunohistochemistry and molecular biology studies on the biopsy material. It is important to emphasize that neither trucut biopsy nor FNAC upstages pediatric renal tumors.…”

Fine Needle Aspiration Cytology of Fetal Rhabdomyomatous and Teratoid Wilms Tumor

“…5 Cytologic features of FRN are available from a few reports. 4,10 We have found aspirates from FRN to have a stromal predominant appearance, but blastema and tubules were seen in all 3 instances. A diagnosis of WT is therefore possible on careful screening.…”

“…4 be a reflection of underlying differences in molecular pathogenesis. 4 FRN is a variant of WT composed chiefly of fetal striated muscle (rhabdomyoblasts). It is rare, constituting 2.1% 8 to 4.5% 10 of WT.…”

“…Rhabdoid tumor of the kidney, despite its name, lacks the myotubes of rhabdomyoblasts as well as the stromal predominant character of FRN and is composed of round to oval cells having cytoplasmic inclusions and nuclei with prominent nucleoli. 4 Clear cell sarcoma of the kidney can have spindle cells but is usually accompanied by mucopolysacharide substance. The cells of clear cell sarcoma have cytoplasm and nuclear grooves.…”

“…2,3 Recent attention has focused on unusual variants of WT that may cause diagnostic difficulty on aspirates. 4 Fetal rhabdomyomatous nephroblastoma (FRN) is a rare variant of stromal predominant WT,…”