The Oncocytic Variant of Poorly Differentiated Thyroid Carcinoma Shows a Specific Immune-Related Gene Expression Profile

BACKGROUND

Poorly differentiated thyroid cancer (PDTC) is a rare, follicular cell-derived neoplasm with an unfavorable prognosis. The oncocytic variant of PDTC may be associated with even more adverse outcome than classical PDTC cases, but its specific molecular features are largely unknown. Our aim was to explore the immune-related gene expression profile of oncocytic and classical PDTC, in correlation with clinical and pathological characteristics (including programmed death ligand 1 [PD-L1] expression) and outcome, and in comparison with a control group of well-differentiated follicular carcinomas (WDFCs), including conventional follicular carcinomas (FTCs) and Hürthle cell carcinomas (HCCs).

METHODS

A retrospective series of 48 PDTCs and 24 WDFCs was analyzed by means of NanoString technology employing the nCounter PanCancer Immune Profiling panel. Gene expression data were validated using quantitative real-time polymerase chain reaction.

RESULTS

Oncocytic PDTCs showed a specific immune-related gene expression profile, with higher expression of LAIR2, CD274, DEFB1, IRAK1, CAMP, LCN2, LY96, and APOE, and lower expression of NOD1, as compared to conventional PDTCs. This molecular signature was associated with increased intratumoral lymphocytic infiltration, PD-L1 expression, and adverse outcome. Three of these genes, CD274, DEFB1, and IRAK1, as well as PD-L1 expression, were also the hallmarks of HCCs as compared to FTCs. By contrast, the panel of genes differentially regulated in PDTCs as compared to WDFCs was unrelated to the oncocytic phenotype.

CONCLUSIONS

Our results revealed a distinctive immune-related gene expression profile of oncocytic PDTC and confirmed a more aggressive outcome in this cancer subtype. These findings may provide guidance when exploring novel immunotherapeutic options for oncocytic PDTC patients.

Oncocytoma-like renal tumor with transformation toward high-grade oncocytic carcinoma: a unique case with morphologic, immunohistochemical, and genomic characterization

Renal oncocytoma is a benign tumor with characteristic histologic findings. We describe an oncocytoma-like renal tumor with progression to high-grade oncocytic carcinoma and metastasis. A 74-year-old man with no family history of cancer presented with hematuria. Computed tomography showed an 11 cm heterogeneous multilobulated mass in the right kidney lower pole, enlarged aortocaval lymph nodes, and multiple lung nodules. In the nephrectomy specimen, approximately one third of the renal tumor histologically showed regions classic for benign oncocytoma transitioning to regions of high-grade carcinoma without sharp demarcation. With extensive genomic investigation using single nucleotide polymorphism-based array virtual karyotyping, multiregion sequencing, and expression array analysis, we were able to show a common lineage between the benign oncocytoma and high-grade oncocytic carcinoma regions in the tumor. We were also able to show karyotypic differences underlying this progression. The benign oncocytoma showed no chromosomal aberrations, whereas the high-grade oncocytic carcinoma showed loss of the 17p region housing FLCN (folliculin [Birt-Hogg-Dubé protein]), loss of 8p, and gain of 8q. Gene expression patterns supported dysregulation and activation of phosphoinositide 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homolog (Akt), mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK), and mechanistic target of rapamycin (serine/threonine kinase) (mTOR) pathways in the high-grade oncocytic carcinoma regions. This was partly attributable to FLCN underexpression but further accentuated by overexpression of numerous genes on 8q. In the high-grade oncocytic carcinoma region, vascular endothelial growth factor A along with metalloproteinases matrix metallopeptidase 9 and matrix metallopeptidase 12 were overexpressed, facilitating angiogenesis and invasiveness. Genetic molecular testing provided evidence for the development of an aggressive oncocytic carcinoma from an oncocytoma, leading to aggressive targeted treatment but eventual death 39 months after the diagnosis.

Clinical features of thyroid autoimmunity are associated with thyroiditis on histology and are not predictive of malignancy in 570 patients with indeterminate nodules on cytology who had a thyroidectomy

BACKGROUND

The relationship between thyroid autoimmunity and cancer is still uncertain.

PATIENTS

We approached this issue in 570 consecutive patients submitted to thyroidectomy for an indeterminate nodule on cytology. Thyroid autoimmunity was defined as positivity of circulating thyroid autoantibodies (TAb), autoimmune hypo- or hyperthyroidism, thyroid hypoechogenicity on ultrasound, and lymphocytic infiltration on histology.

RESULTS

TAb were found in 122/570 (21.4%), hypoechogenicity in 115/570 (20.1%), and lymphocytic infiltration in 117/570 (20.5%) of patients. The three features of thyroid autoimmunity were highly concordant: hypoechogenicity was observed in 71/448 (15.8%) patients with negative TAb and in 44/122 (36%) with positive TAb (P < 0.0001); lymphocytic infiltration was found in 53/448 (11.8%) patients with negative TAb and in 64/122 (52.4%) with positive TAb (P < 0.0001); hypoechogenicity on ultrasound was observed in 73/453 (16.1%) patients without, and in 42/117 (35.9%) with lymphocytic infiltration (P < 0.0001). None of these parameters was associated with malignancy. TAb were found in 32/135 (23.7%) patients with carcinoma and in 90/435 (20.6%) with a benign lesion (P = NS); hypoechogenicity was observed in 26/135 (19.2%) patients with carcinoma and in 89/435 (20.4%) patients with benign lesions (P = NS); lymphocytic infiltration was present in 28/135 (20.7%) patients with carcinoma and in 89/435 (20.4%) with benign lesions (P = NS). The frequency of cancer in 11 patients with clinically overt thyroid autoimmune disease did not differ from that observed in the whole study group.

CONCLUSION

In this group of patients with indeterminate thyroid nodules at cytology, clinical and pathological criteria of thyroid autoimmunity were strongly concordant and not associated with malignancy.

Cytokeratins 7 and 20 immunoreactivity in chromophobe renal cell carcinomas and renal oncocytomas

Chromophobe renal cell carcinomas and renal oncocytomas share morphologic similarities and may present a diagnostic challenge on routine hematoxylin-eosin staining. Currently recommended additional studies of Hale's colloidal iron staining and electron microscopy are often difficult to interpret and technically challenging and may not be readily available. Previous studies have reported conflicting results with regard to the cytokeratin 7 staining pattern in chromophobe renal cell carcinomas and renal oncocytomas. Cytokeratin 20 expression in chromophobe renal cell carcinomas has not previously been studied. Formalin-fixed paraffin-embedded tissue of 11 chromophobe renal cell carcinomas and 21 renal oncocytomas were retrieved from the archived files (1984-2000) of four teaching hospitals. Of the 11 chromophobe renal cell carcinomas, eight stained positive (73%) for cytokeratin 7, one stained focally positive (9%), and two cases (18%) were completely negative. Cytokeratin 7 staining of the 21 oncocytomas revealed 4 positive (19%), 7 focally positive (33%), and 10 negative cases (48%). Cytokeratin 20 was uniformly negative on all 11 cases of chromophobe renal cell carcinomas and all 21 cases of oncocytomas. Cytokeratin 7 does not appear to show the consistent immunoreactivity in chromophobe renal cell carcinomas and renal oncocytomas, as has been previously suggested. Cytokeratin 20 immunostaining in chromophobe renal cell carcinomas and renal oncocytomas is uniformly negative. Despite the technical and interpretive challenges of Hale's colloidal iron, it is still the most useful stain in differentiating chromophobe renal cell carcinomas from renal oncocytomas.

S-100 protein+ dendritic cells and CD34+ dendritic interstitial cells in thyroid lesions

Dendritic cells (DCs) are antigen-presenting cells and mature from precursor CD34+ stromal cells (dendritic interstitial cells [DICs]) or monocytes. The aim of the present study was to gain insight into the local immune response to various thyroid lesions. We investigated, immunohistochemically, the presence of S-100+ DCs and CD34+ DICs in 13 papillary carcinomas, 10 follicular carcinomas, 7 follicular adenomas, 1 Hurthle cell carcinoma, 1 Hurthle cell adenoma, 2 medullary carcinomas, 6 undifferentiated carcinomas, and 3 nodular goiters. Dense infiltrates of S-100+ DCs were noted in the majority of papillary carcinomas (mean: 66.4), while moderate infiltrates were observed in follicular adenomas (mean: 23.3), follicular carcinomas (mean: 23.5), and undifferentiated carcinomas (mean: 31.6). The remaining lesions showed slight infiltrates of scattered DCs. DICs were noted exclusively in neoplastic lesions, specifically at the periphery and within the tumor capsule. The increased number of DCs in papillary carcinomas is possibly correlated with their good prognosis. The specific distribution of DICs suggests a possible contribution to growth regulation of thyroid neoplasms.