renal cell carcinomas form a heterogeneous group of tumours which can be divided into several subgroups according to their cytology, architecture, and the part of the nephron from which tumour cells are derived:five basic cell types are recognized: clear-cell, chromophilic-cell (also called papillary renal cell carcinomas (PRCC), herein described), chromophobic-cell, oncocytic-cell, and collector duct cell typesa certain correlation exists between cell type and architecture of the tumour: the clear-cell type tends to show compact growth, while the chromophilic-cell type is more readily associated with tubulo-papillary architecture

a hereditary form, called Hereditary papillary renal cell carcinoma, of autosomal dominant transmission, has been recently recognized; it predisposes to develop multiple, bilateral renal tumours

papillary renal cell carcinomas (PRCC) represent about 10% of all renal cell tumours; there is a clear excess of male patients (male to female ratio: 5 to 1)

except a very rare subtype characterized by a translocation t(X;1)(p11;q21) or other abnormalities involving Xp11, PRCC do not show a recurrent structural chromosome rearrangement, but display non random numerical abnormalities; this contrasts with clear-cell renal cell carcinomas which are associated with various deletions of 3pPRCC are characterized by loss of Y chromosome in men, trisomy or tetrasomy 7 and 17, trisomies 16, 20, and 12, by order of frequency; these chromosome imbalances have been confirmed by genomic comparative hybridizationmultifocal PRCC show the same numerical anomalies, with trisomies sometimes in various combinations in tumours within the same kidney or in both kidneysthe confrontation of karyotypic abnormalities with histopathological data suggest that specific chromosome imbalances may make it possible to distinguish benign papillary adenoma from malignant PRCC; the small papillary tumours without any morphological or clinical sign of malignancy are characterized by a combination of loss of Y, and excess of chromosomes 7 and 17, only, whereas tumours with aggressive growth and metastatic dissemination show more complex karyotypic changes, in addition to polysomy 7 and 17; it is suggested that tumours with tri- or tetrasomy 7 and 17 correspond to papillary adenomas, and that tumours with more complex karyotypic changes are papillary carcinomas, irrespective of their size