Many histological variants of PTC have been described and some are known to have prognostic significance. However, their relative frequencies and associated clinicopathological features in a large cohort of patients with PTC treated at a single institution have seldom been documented. We reclassified 1035 malignant thyroid tumors treated in a 30-yr study period, into variants of PTC according to current histological criteria and analyzed their features. Six hundred and fifty two patients (153 men; 499 women) with PTC were identified. PTC accounted for 72.8% of primary thyroid cancers. Conventional papillary carcinoma (n = 300) accounted for 46% of PTC and papillary microcarcinoma 27.8% (n = 181). The frequencies of the common histological variants were follicular (17.6%, n =115), tall cell (4%, n = 26), and diffuse sclerosing (1.8%, n = 12). Uncommon histological variants including solid (n = 5), diffuse follicular (n = 5), papillary carcinoma with focal insular component (n = 3), columnar cell (n = 2), papillary carcinoma with fasciitis-like stroma (n = 2), and oncocytic (n = 1) were also noted. Histological variants of PTC had different age presentation, tumor size, frequencies of lymph node metastases, calcification, metaplastic bone, and psammoma bodies, when compared with conventional PTC. We conclude that a high prevalence of different variants of PTC with distinct clinicopathological features can be documented. Recognition of these histological variants may be important for better management of patients with PTC.

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Recent evidence suggests that small non-coding RNAs such as microRNA (miRNA) encapsulated in exosomes represent an important mechanism of communication between the cells. Exosomal miRNAs play an important role in carcinogenesis via enhancing the cell to cell communication and targeting the cell growth molecular pathways which in turn facilitate metastasis in cancers. Despite progressive advances, the current methods for the exosomal miRNA detection mostly rely on labor-intensive sequencing approaches which are often prone to amplification bias and require costly and bulky equipment. Herein, we report an electrochemical approach for the detection of cancer-derived exosomal miRNAs in human serum samples by selectively isolating the target miRNA using magnetic beads pre-functionalized with capture probes and then directly adsorbing the targets onto a gold electrode surface. The level of adsorbed miRNA is detected electrochemically in the presence of an [Fe(CN)6]4-/3- redox system. This method enabled an excellent detection sensitivity of 1.0 pM with a relative standard deviation (%RSD) of <5.5% in cancer cells and serum samples (n = 8) collected from patients with colorectal adenocarcinoma (CRC). We believe that our approach could be useful in clinical settings for the quantification of exosomal miRNA in cancer patients.

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