teratoid wilms tumor , a rare variant of nephroblastoma , has a predominance of heterologous elements . to date less than 30 cases of teratoid wilms tumor have been reported in the literature.[13 ] there is only one case in the literature , which has the squamous epithelial component comprising 70% of the tumor . we describe a case in which the squamous epithelium with keratin cysts comprised majority ( about 75% ) of tumor mass . metastasis is seldom reported in teratoid wilms . a -2-year - old boy presented with palpable mass on the right side of abdomen for 2 months . physical examination revealed a firm mass that was palpable in the lumber region . contrast - enhanced computed tomography ( cect ) scan showed large hetrodense lesion in the right lumber region measuring 17 cm  8 cm  7 cm . the right lung showed nodular opacities in posterior and lateral basal segments of about 0.5 cm in diameter suggestive of metastasis . cect scan done after 6 weeks of chemotherapy showed little change in the size of tumor and the patient underwent nephrectomy . grossly , nephrectomy specimen measured 17 cm  8 cm  6 cm that was soft in consistency . the cut section was predominantly solid and pale grey with areas of cystic change , necrosis , and hemorrhage . a thin segment of normal kidney was seen compressed at periphery [ figure 1 ] . gross - predominantly cystic appearance of teratoid kidney microscopically , the tumor showed classical triphasic pattern with blastemal , epithelial , and mesenchymal components without anaplasia ; about 75% of the tumor revealed areas of squamous differentiation with keratin pearl formation but without adnexal structures [ figures 2 and 3 ] . there were also small foci of mature adipose tissue and glial tissue [ figure 4 ] . wilms tumor is an embryonic tumor typically composed of variable admixture of blastematous , epithelial and stromal components . wilms tumor can include heterologous elements in addition to these components and variend et al in 1984 , coined the term teratoid wilms tumor for them . . defined teratoid wilms as a tumor that contains hetrologous elements comprising more than 50% of the tumor mass . to date , less than 30 cases of teratoid wilms tumors have been reported.[13 ] the pathogenesis of this entity is still debated ; it is likely that it originates from totipotent primitive metanephric blastema . the variable presence of intracellular matrix proteins may influence the presence , extent , and diversity of hetrologous differentiation . the teratoid elements seen frequently are skeletal muscle , smooth muscle , adipose tissue , glial tissue , cartilage , bone , and are generally assumed to represent aberrant mesenchymal differentiation . there is only one case of teratoid wilms in the literature , reported by karaka i et al , which had squamous epithelial component comprising 70% of the tumour . we report a case that showed the familiar triphasic pattern of nephroblastoma along with the extensive squamous epithelial components constituting about 75% of the tumor . the differential diagnosis of teratoid wilms is intrarenal teratoma , metastatic germ cell tumor , and retroperitoneal infiltration of teratoma . in our case , classical triphasic pattern of wilms tumour was seen and there was no attempt to form the adnexal structures or organogenesis thus ruling out intrarenal teratoma . also , the presence of normal testis excluded the possibility of metastatic testicular germ cell tumor . renal capsule was also free of tumor so retroperitoneal infiltration of teratoma was also ruled out . although it is reported that teratoid wilms tumor is not usually aggressive or has metastatic potential . the case reported by karaka et al , which had extensive squamous areas , died of metastasis . whether the squamous differentiation is associated with higher stage at presentation remains to be seen . the treatment of teratoid wilms tumor has not yet been established because of its rarity and varying tumor components . both surgeons and pathologists should be aware that the treatment of this rare variant should be focused on total surgical removal of the tumor .