RESUMO
We report a case of a 16-year-old girl with a left renal tumor discovered by her family practitioner. On physical examination the patient had a painless abdominal mass, located in the upper medium portion of the abdomen on the left side with a voussure of the abdominal wall. Ultrasound and abdominal pelvic CAT scan revealed a large heterogeneous mass with calcifications in the inferior portion of the left kidney. We made touch-imprint cytological preparations of the biopsy fragments, obtained under ultrasound guidance. Cytological analysis revealed highly cellular smears with malignant cells arranged in large clusters or rarely isolated, sometimes surrounding hyaline nodules with numerous psammoma bodies. After May-Grünwald-Giemsa staining, cells displayed moderately irregular nuclei with an abundant and pale basophilic cytoplasm with well-defined borders and a finely granular texture. The diagnosis of a special type of renal cell carcinoma was suspected, and was then confirmed after examination of the biopsy sample and the corresponding surgical specimen. The histomorphologic features were those of a renal cell carcinoma associated with an Xp11.2 translocation. Immunohistochemistry revealed this translocation by showing nuclear positivity in tumor cells for an antibody raised against the TFE3 protein. The clinical outcome was marked several months later by metastases in lymph nodes, bone, lung, and adrenal gland as well as a local recurrence.