Wilms' tumor, named after the 19th
century German surgeon Carl Max Wilhelm Wilms, is probably derived from primitive metanephric blastema. The histological appearance is characterized by marked structural diversity. Classic Wilms' tumor is composed of three types of cells – blastemal, stromal, and epithelial; although the occurrence of all three types in the same case is uncommon [3
Adult Wilms' tumor is diagnosed based on the criteria given by Kilton, Mathews, and Cohen [4
]. These include 1) the tumor under consideration should be a primary renal neoplasm; 2) presence of primitive blastemic spindle or round cell component; 3) formation of abortive or embryonal tubules or glomerular structures; 4) no area of tumor diagnostic of renal cell carcinoma; 5) pictorial confirmation of histology and 6) patient's age >15 years. Kilton et al (1980) reported 35 cases of adult Wilms' tumor complying with all the above criteria.
To the best of our knowledge, the present case is only the second case in Indian literature to have the classic triphasic histology. Blastemic component was predominant in the histology in 6 out of the 8 adult Wilms' reported in Indian literature [5
The differential diagnosis of an adult Wilm's tumor with mainly epithelial differentiation includes metanephric adenoma. A predominant blastemic Wilms' tumor has a strong resemblance to small, blue round cell tumors which commonly include lymphoma, peripheral neuro-ectodermal tumor and rhabdomyosarcoma; and rarely metastatic small cell tumors from lung, immature teratoma, and primary renal cell sarcoma. Extensive search for any other components is needed as a poorly differentiated renal carcinoma can have large sarcomatous areas resembling blastema [4
Most adults present with local pain and haematuria, in contrast to the palpable boggy mass which is more common in children. In adults, Wilms' tumor is larger and ill-defined, with areas of necrosis and hemorrhage. About half of the patients have stage 3 or 4 disease [7
]. There are about ten cases of extra-renal Wilms' tumors in adults documented in the literature. Four of them were in the retroperitoneal region, two each in the ovary and endometrium, and one each in ovotestis and prostate [4
Tremendous data on the biology and epidemiology of Wilms' tumor has been generated by the National Wilms' Tumor Study (NWTS) which was established in the USA in 1969. An update from the NWTS group about treatment outcomes in adults with favorable histology Wilms' tumor (FHWT) described 45 patients treated in the modern era. The overall survival rate was 82% [8
In 2004, Reinhard et al reported their experience with 30 cases of adult Wilms Tumor [2
]. A complete remission was achieved in 24 of their patients. Event-free survival was 57%, and overall survival was 83%. They concluded that adults can be cured in a high percentage by a multimodal treatment according to pediatric protocols.
Wilms' tumor in adults has a worse prognosis than in the pediatric population, a phenomenon for which there is no adequate explanation [1
]. As adult Wilms' tumor is rare, randomized trials cannot be performed. It has been suggested by most authors that to evaluate concepts for adequate treatment, results of randomized trials with childhood Wilms' tumor should be extrapolated. National Wilms' Tumor Study (NWTS) and other studies have recommended multimodal therapy for the disease with surgery, chemotherapy (actinomycin D, vincristine and doxorubicin) for 15 months and tumor bed irradiation in the case of stage 3 disease. Less aggressive therapy with two drugs is advised in stage 1 and 2 disease.