Interphase cytogenetics of renal cortical neoplasms. Correlation with DNA ploidy by flow cytometry

A non-diploid DNA status is linked to poor prognosis in renal cell cancer

Purpose

DNA ploidy measurement has earlier been suggested as a potentially powerful prognostic tool in many cancer types, but the role in renal tumors is still unclear.

Methods

To clarify its prognostic impact, we analyzed the DNA content of 1320 kidney tumors, including clear cell, papillary and chromophobe renal cell carcinoma (RCC) as well as renal oncocytoma and compared these data with clinico-pathological parameters and patient prognosis.

Results

A non-diploid DNA content was seen in 37% of 1276 analyzable renal tumors with a striking predominance in chromophobe carcinoma (74.3% of 70 cases). In clear cell carcinoma, a non-diploid DNA content was significantly linked to high-grade (ISUP, Fuhrman, Thoenes; p < 0.0001 each), advanced tumor stage (p = 0.0011), distant metastasis (p < 0.0001), shortened overall survival (p = 0.0010), and earlier recurrence (p < 0.0001). In papillary carcinoma, an aberrant DNA content was significantly linked to high Fuhrman grade (p = 0.0063), distant metastasis (p = 0.0138), shortened overall survival (p = 0.0010), and earlier recurrence (p = 0.0003).

Conclusion

In summary, the results of our study identify a non-diploid DNA content as a predictor of an unfavorable prognosis in clear cell and papillary carcinoma.

Electronic supplementary material

The online version of this article (10.1007/s00345-020-03226-8) contains supplementary material, which is available to authorized users.

Interphase cytogenetics of multicentric renal cell tumours confirm associations of specific aberrations with defined cytomorphologies

To demonstrate associations of certain chromosomal aberrations with defined renal cell tumour (RCT) subtypes, we analysed 239 tumour nephrectomy cases for specimens with multicentric tumours. Chromosomal in situ hybridization was then performed on 15 cases with 34 foci (16 conventional renal cell carcinomas (RCCs), and 18 papillary RCTs (11 carcinomas and seven adenomas) for specific chromosomal aberrations, using alpha-satellite probes for chromosomes 3, 7 or 17. Particular preference was given to cases which had separate foci with different cytomorphologies. Furthermore, we compared aberrations in relation to tumour size, stage, grade and between different foci in a specimen. Thirty-four cases had multiple tumours. Forty-seven per cent of the multicentric tumours were conventional RCCs and 53% papillary RCTs (against 83% solitary conventional RCCs and 5% solitary papillary RCTs). Three conventional RCCs sized 8 mm (G3), 13 cm (pT2, G2) and 15 cm (pT3b, G3), respectively, revealed monosomy 3, and 13 were disomic. Seventeen papillary RCTs (11 carcinomas and six adenomas) displayed trisomy 17, irrespective of size or grade. Four papillary carcinomas and six papillary adenomas had trisomy 7, and the rest (seven papillary carcinomas and one papillary adenoma) revealed disomy 7. In conclusion, papillary RCTs were tendentially multicentric. Although specific for conventional RCCs heedless of size, monosomy 3 was only observed in high-grade and/or advanced tumours. Trisomy 17 was only detectable in papillary RCTs irrespective of tumour state, showing increased copies with tumour growth. Papillary RCTs also appeared to lose some copies of chromosome 7 with tumour progress, possibly reflecting malignancy.

Limited nonrandom chromosomal aberrations in a recurrent adenoid cystic carcinoma of the parotid gland

We present the cytogenetic, interphase fluorescence in-situ hybridization (FISH) and DNA content findings in a clinically aggressive adenoid cystic carcinoma (ADCC) of the parotid gland. The tumor manifested diploid chromosomal and DNA content by cytogenetic, interphase FISH and flow cytometry. G-banding analysis revealed inv(5)(p15.2q33) and t(6;15)(q25;q15) as the only structural alterations in all 30 metaphases examined. The limited structural abnormalities found in this recurrent lesion suggest that they may constitute a primary or early event in the development of this tumor. The involvement of 6q region in our tumor and in some of the previously reported ADCC supports the association between this region and the evolution of at least a subset of these tumors.

Concurrent cytogenetic, interphase fluorescence in situ hybridization and DNA flow cytometric analyses of a carcinoma ex-pleomorphic adenoma of parotid gland

We report the cytogenetic, fluorescence in situ hybridization (FISH), and DNA ploidy analyses of a high grade carcinoma ex-pleomorphic adenoma of the submandibular gland. Our overall combined analyses showed a marked DNA aneuploidy and numerical abnormalities involving all chromosomes. Cytogenetic analysis revealed a near tetraploid modal chromosomal number with tetraploid loss of chromosomes Y, 1, 6, 9, 11, 14, 15, 17, and 19-21 and hypertetraploid gain of chromosomes 7, 8, and 22. The structural abnormalities included der(1;14)(q10;q10), del(6)(q15q34), +del(6)(q15q34), +der(8) t(1;8)(q12;q12.2),der(9;19)(q10;q10),add(14)(p11.2),i(20)(q10),der(21) t(8;21)(q11.2;q22.3),+der(21)t(8;21) (q11.2;q22.3). Interphase FISH of the primary and short-term cultured cells using directly labeled pericentromeric probes for chromosomes 6-12, 17, 18, and Y resulted in alterations corresponding to the cytogenetic findings. DNA ploidy analysis of both the primary and cultured tumor cells showed a hyperdiploid stemline with DNA indices of 2.6. The results indicate that: (1) marked numerical, structural chromosomal, and DNA content abnormalities are present in this tumor; and (2) alteration at 8q and 6q regions, together with previous results, suggest an association between these events and the development and/or progression of this tumor.

EGF-r gene copy number changes in renal cell carcinoma detected by fluorescence in situ hybridization

Expression of epidermal growth factor receptor (EGF-r) is a frequent event in renal cell carcinoma (RCC). To investigate the role of EGF-r gene copy number changes related to EGF-r overexpression, 50 RCC specimens were examined by fluorescence in situ hybridization (FISH) and immunohistochemistry. Dual-labelling FISH with a repetitive pericentromeric probe for chromosome 7 and a probe for the EGF-r gene (at 7p13) was performed to analyse the EGF-r copy number in relation to chromosome 7 copy number on a cell-by-cell basis. Polysomy 7 was frequent in all histological types of RCC. Chromosome 7 polysomy was found in 26 of 35 clear cell (74 per cent), nine of nine papillary, and three of three chromophobe RCCs. EGF-r gene copy number was closely associated with the chromosome 7 copy number on a cell-by-cell basis. No EGF-r gene amplifications were found. EGF-r positivity was found in 37 of 50 cases (74 per cent) by immunohistochemistry. EGF-r positivity was more common in clear cell (81 per cent) than in papillary tumours (40 per cent; P = 0.029). Neither chromosome 7 nor EGF-r gene copy number was associated with EGF-r expression, indicating that an increased gene dosage is not a mechanism of EGF-r overexpression in RCC.

Multiple unrelated translocations in a metastatic epimyoepithelial carcinoma of the parotid gland

We report the cytogenetic, fluorescence in-situ hybridization (FISH) and DNA flow cytometric analysis of a rare metastatic epimyoepithelial carcinoma of the parotid gland to the lung with a clinical course of 29 years. DNA content and FISH analyses of tumor and short-term culture cells showed diploid DNA content and lack of numerical chromosomal abnormalities. Immunohistochemical analysis of the short-term culture cells showed predominantly keratin positive and sparse desmin staining supporting an epithelial rather than myoepithelial origin. Cytogenetic analysis showed 46,XY karyotype with clonal translocations of t(3;22)(q13.2;q13.1), t(1;7)(q21;q22), t(8;9)(p10;p10), and t(5;6) (q35;q21). Our findings indicate that these alterations developed in a diploid stemline during tumor progression and in the epithelial component of this tumor.

Chromosomal and DNA ploidy characterization of salivary gland neoplasms by combined FISH and flow cytometry

Concurrent DNA ploidy by flow cytometry and interphase FISH analysis of chromosomes 6 through 12, 17, 18, X, and Y were prospectively performed on 22 salivary gland neoplasms (four benign and 18 malignant) to investigate the diagnostic and biological implications of their alterations in these neoplasms. Our results show that benign neoplasms lack DNA aneuploidy and numerical chromosomal abnormalities. Low-grade malignant neoplasms, except for two lesions, manifested small chromosomal gains and losses and were generally DNA diploid or near-diploid aneuploid, whereas all high-grade tumors showed marked polysomy and were DNA aneuploid. Marked intratumoral and intertumoral chromosomal heterogeneity also were noted in and between individual tumors. Although polysomy was the main finding in DNA aneuploid lesions, monosomy was more noted in DNA diploid neoplasms and was restricted to chromosomes 8, 11, and 17. Significant correlation between the DNA index, chromosomal aneusomy, histological grade, and tumor stage was noted. Our study indicates that (1) benign salivary gland neoplasms lack gross DNA content and numerical chromosomal abnormalities, (2) clonal chromosomal alterations are manifested in most DNA diploid and all DNA aneuploid malignant tumors, (3) chromosomal gain is the most common alteration; chromosomal loss is less frequent and restricted to certain chromosomes, and (4) DNA aneuploidy and chromosomal aneusomy characterize tumors with aggressive features.

Renal cell carcinoma: Pathological prognostic criteria

– Pathological criteria so far employed in the prognosis of renal cell carcinoma provide no clinically useful information. This paper emphasises the possibilities offered by histopathology today for tackling this clinical problem more effectively. Nuclear analysis, with objective and quantitative evaluation of the degree of distortion, may provide extremely useful information. The authors correctly classified 90% of the 50 cases of renal cell carcinoma considered and whose follow-up at 5 years was known.