BackgroundThe immunohistochemical demonstration of Enhancer of zeste homologue 2 (EZH2) proved to be a useful marker in several tumor types. It has been described to distinguish reliably hepatocellular carcinomas from liver adenomas and other benign hepatocellular lesions. However, no other types of malignant liver tumors were studied so far.MethodsTo evaluate the diagnostic value of this protein in hepatic tumors we have investigated the presence of EZH2 by immunohistochemistry in hepatocellular carcinomas and other common hepatic tumors.EZH2 expression was examined in 44 hepatocellular carcinomas, 23 cholangiocarcinomas, 31 hepatoblastomas, 16 other childhood tumor types (rhabdomyosarcoma, neuroblastoma, Wilms’ tumor and rhabdoid tumor), 17 metastatic liver tumors 24 hepatocellular adenomas, 15 high grade dysplastic nodules, 3 biliary cystadenomas, 3 biliary hamartomas and 3 Caroli’s diseases.ResultsMost of the malignant liver tumors were positive for EZH2, but neither of the adenomas, cirrhotic/dysplastic nodules, reactive and hamartomatous biliary ductules stained positively.ConclusionsOur immunostainings confirm that EZH2 is a sensitive marker of hepatocellular carcinoma, but its specificity is very low, since almost all the investigated malignant liver tumors were positive regardless of their histogenesis. Based on these results EZH2 is a sensitive marker of malignancy in hepatic tumors. In routine surgical pathology EZH2 could be most helpful to diagnose cholangiocarcinomas, because as far as we know this is the first marker to distinguish transformed and reactive biliary structures. Although hepatoblastomas also express EZH2, the diagnostic significance of this observation seems to be quite limited whereas, the structurally similar, other blastic childhood tumors are also positive.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1173195902735693

Background: The immunohistochemical detection of Enhancer of zeste homologue 2 (EZH2) proved to be a useful tool to recognize the malignant nature of tumors in a wide variety of neoplasms. The histological diagnostics of salivary gland tumors is a challenging task, and a reliable marker of malignancy would be extremely helpful. Methods: EZH2 expression was investigated in 54 malignant and 40 benign salivary gland tumors of various histological types by standard immunohistochemistry. Results: The majority (n = 52) of the malignant tumors stained positively, while all the investigated benign tumors were negative for EZH2. Conclusions: EZH2 expression in salivary gland tumors, similarly to the tumors of other organs is not characteristic for any tumor type, but is a solid marker of the malignant nature of the tumors.

Unbiased morphological characterization of cirrhotic livers can provide valuable, clinically relevant information. Similar evaluation of routine core biopsies may increase the significance of this 'Gold Standard' examination.

In March 2020, the World Health Organization characterized COVID-19 as a pandemic. By May 2021, 37 cases of subacute thyroiditis (SAT) associated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) had been reported in the literature. We report a patient diagnosed with SAT associated with COVID-19 and review the previously reported cases. A 31-year-old female with no significant previous history developed SAT 5 weeks after SARS-CoV-2 infection. She presented with anterior neck pain and fever. Thyroid function tests revealed hyperthyroidism with slightly increased inflammatory markers. Thyroid ultrasound showed diffuse hypoechoic left lobe and a hypoechoic area in the right lobe. On the fine-needle-aspiration biopsy, large histiocytes, disrupted and normal follicles, and multinucleated giant cells within colloid were seen. Under oral corticosteroid therapy, clinical progression was rapid. Seven weeks later, all thyroid function tests and inflammatory markers normalized. During the recent viral outbreak, clinicians should keep in mind the possibility of SAT after COVID-19, and patients with symptoms of SAT should be tested for SARS-CoV-2.