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Background Histopathological characteristics affecting the detectability of clinically significant prostate cancer (csPCa) on magnetic resonance imaging (MRI) remain unclear. This study aimed to compare the histopathology between MRI‐detectable and MRI‐undetectable cancers, emphasizing intraductal carcinoma of the prostate (IDC‐P) and predominant Gleason pattern 4 subtype. Methods This single‐center retrospective study enrolled 153 consecutive patients with 191 lesions who underwent preoperative multiparametric MRI and subsequent radical prostatectomy. MRI/histopathological findings and area fractions of histological components (cancer cells, stroma, and luminal spaces) of MRI‐detectable and MRI‐undetectable cancers were compared. Data were analyzed using Fisher's exact, independent t, or Mann–Whitney U tests. Results Overall, 148 (77%) and 43 (23%) cancers were MRI‐detectable and MRI‐undetectable, respectively. MRI‐detectable cancers were significantly larger than MRI‐undetectable cancers (p = 0.03). The percentage of lesions in Grade Group 3 or higher was significantly higher among MRI‐detectable cancers than among MRI‐undetectable cancers (p = 0.02). MRI detectability of csPCa was associated with increases in relative area fractions of cancer cells (p < 0.001) and decreases in those of stroma (p < 0.001) and luminal spaces (p < 0.001) in prostate cancer (PCa) than the percentage of Gleason pattern 4 (p = 0.09). The percentage of lesions containing IDC‐P was similar for MRI‐detectable and MRI‐undetectable cancers (40% vs. 33%; p = 0.48). The distribution of cribriform gland subtypes was not significantly different between MRI‐detectable and MRI‐undetectable Gleason pattern 4 subtype cancers (p > 0.99). Contrarily, the ratio of fused gland subtype was significantly higher in MRI‐detectable than in MRI‐undetectable cancers (p = 0.03). Furthermore, the ratio of poorly‐formed gland subtype was significantly higher in MRI‐undetectable than in MRI‐detectable cancers (p = 0.01). Conclusions MRI detectability of csPCa is strongly associated with the relative area fractions of cancer cells, stroma, and luminal spaces in PCa rather than conventional histopathological parameters. Neither the presence nor the percentage of IDC‐P affected MRI detectability.

A carcinoma displaying undifferentiated features with dense lymphoplasmacytic infiltration is defined as lymphoepithelioma-like carcinoma (LELC). Intrahepatic cholangiocarcinoma (ICC) with LELC components is rare, and most LELCs are associated with Epstein-Barr virus (EBV). We report here on a case of ICC with LELC components not associated with EBV. A 65-year-old woman was incidentally found to have a hepatic tumor in the caudate lobe. An extended right hepatectomy with lymphadenectomy was performed. Histologically, the tumor was mainly composed of large undifferentiated epithelial cells with vesicular nuclei, prominent nucleoli, indistinct cell borders, and heavy small lymphocytic infiltration, which are the characteristic features of LELC. Immunohistochemical studies revealed that the tumor cells were positive for cytokeratin 19 but were negative for glypican 3. In situ hybridization using EBV-encoded RNA was negative. Therefore, a diagnosis of ICC with LELC components not associated with EBV was made. Because there is limited information available regarding the prognosis and treatment of ICC with LELC components because of the limited number of reported cases, additional studies will be needed to clarify the clinicopathologic features of this disease.

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BackgroundOn 18F-fluorodeoxyglucose (FDG)-positron emission tomography (PET), diffuse uptake in the thyroid gland is often observed in patients with Hashimoto’s thyroiditis. In this study, we evaluated the factors associated with diffuse uptake by comparing Hashimoto’s thyroiditis patients with or without diffuse uptake in the thyroid.MethodsA retrospective study was conducted of 18 patients with Hashimoto’s thyroiditis who underwent blood tests, thyroid ultrasonography, and FDG-PET during the period from 2014 to 2015. The patients were divided into two groups: one with diffuse thyroid uptake (group 1, n = 13) and one without diffuse thyroid uptake (group 2, n = 5). Clinical and laboratory parameters, including maximum standardized uptake in the thyroid (SUVmax), which was defined as the higher value obtained in either the right or left thyroid lobe, were compared in the two groups.ResultsThe frequency of abnormal findings, such as a rough or heterogeneous pattern, was significantly higher in group 1 (p <  0.01), as were anti-thyroid peroxidase (TPO) antibody titers, anti-thyroglobulin (Tg) antibody titers, and SUVmax (p <  0.01). The frequency of hypothyroidism did not differ significantly in the two groups. Anti-TPO and anti-Tg titers were positively correlated with SUVmax (r = 0.856, p <  0.01 and r = 0.821, p <  0.01, respectively); in univariate analysis, anti-TPO titer was predictive of SUVmax (p <  0.01).ConclusionsThe results of the current study suggest that Hashimoto’s thyroiditis patients with high titers of anti-thyroid antibodies are likely to exhibit intense diffuse FDG uptake in the thyroid, and that thyroid function may be clearly impaired, even in the presence of mild FDG uptake in the thyroid.