Mesenchymal Hamartoma of the Liver and DICER1 Syndrome.

Mesenchymal hamartoma of the liver (MHL) is a benign tumor affecting children that is characterized by a primitive myxoid stroma with cystically dilated bile ducts. Alterations involving chromosome 19q13 are a recurrent underlying cause of MHL; these alterations activate the chromosome 19 microRNA cluster (C19MC). Other cases remain unexplained. We describe two children with MHLs that harbored germline DICER1 pathogenic variants. Analysis of tumor tissue from one of the children revealed two DICER1 "hits." Mutations in DICER1 dysregulate microRNAs, mimicking the effect of the activation of C19MC. Our data suggest that MHL is a new phenotype of DICER1 syndrome. (Funded by the Canadian Institutes of Health Research and others.).

Solitary fibrous tumor: A rare lesion with an unusual paravertebral presentation.

BACKGROUND: Solitary fibrous tumor (SFT) is a rare spindle-cell neoplasm [1]. Although typically originating from pleura, head and neck presentation accounts for about 6-18 % and very few cases have been described in paravertebral and posterior neck spaces [2]. Both computed tomography (CT) scans and magnetic resonance imaging (MRI) help in differential diagnosis of such lesion [3]. However, only histological and immunohistochemical studies give a conclusive diagnosis: CD34, BCL-2, and in particular STAT6 stainings are strongly orientative [4]. Radical surgery with free margin excision is the first treatment option, rarely requiring adjuvant therapy [2]. Prognosis is typically good and strictly related to histological risk assessment [5]. Rare cases of local recurrence and distant metastasis have been described in literature [2]. OBJECTIVE: The purpose of this video is to describe the operative technique of a transcervical removal of a rare case of right paravertebral SFT. We present the diagnostic flowchart, management strategies, surgical technique and we provide anatomical dissection parallelism, which might be of interest to the readers. MATERIALS AND METHODS: A 59-years-old man with a one-year right cervical asymptomatic swelling was referred to our department. A contrasted MRI documented an expansive 6.5 cm capsulated lesion in the deep posterior neck spaces with diffuse contrast enhancement and inhomogeneous appearance. A core needle biopsy was performed, and the results from the initial immunohistochemical panel were not univocal showing positivity for cytokeratins AE1/AE3, PAX8, and no reactivity for CD34. A second immunohistochemical panel was then performed, displaying diffuse nuclear positivity for STAT6, which is a surrogate marker for the NAB2-STAT6 gene fusion, a specific driver mutation of SFT. Therefore, a radical excision was performed via transcervical approach (Video 1). No post-operative complications neither cranio-cervical neurological deficit occurred. RESULTS: In comparison to pre-operative histopathologic study, the definitive histological examination of the whole mass revealed a more classical morphology of SFT. It was classified as an intermediate risk SFT [5]. A complete free margin excision was confirmed. After a multidisciplinary discussion, no adjuvant therapies were suggested. A six- and twelve-months radiological follow-up with MRI showed no evidence of disease. CONCLUSION: SFT may represent a misdiagnosed entity in head and neck spaces and a correct diagnosis through immunohistochemistry is mandatory. Radical excision with free surgical margins should be pursued as adequate goal. Since SFTs show variable risk of metastatic disease, adjuvant radiotherapy should be contemplated in high-risk diseases and a clinico-radiological follow-up with MRI is required.

Tuberculosis: the sanatorium season in the early 20th century.

The creation of hospitals providing specialist care is not a prerogative of our time. As the world wonders how to cope with new pandemics and the age-old problems of the transmission of infections and the isolation of the sick, while the COVID-19 pandemic has been raging, it might be worth glancing back at the period - just over a century ago - when sanatoriums were set up in Italy as part of the fight against consumption.

Ugo Cerletti, Pathologica and electroconvulsive therapy.

Ugo Cerletti was the inventor of the electroconvulsive therapy (ECT) adopted in 1938 to treat schizophrenia. He had a robust education in anatomical pathology, which also left its mark on the journal Pathologica. Although his name is associated with several important moments and breakthroughs in the history of medicine, Ugo Cerletti's reputation has partly suffered from the same fate as his treatment. Electroshock was initially widely adopted, partly because of its low cost and relatively easy application, but with the advent of psychoactive drugs in the 1950s and 1960s, it subsequently came under ferocious criticism. Its fall from grace also affected to some extent the man who had invented it, though this seems hard to justify today.

Possible pathogenetic relationship between Fabry disease and renal cell carcinoma.

The occurrence of renal cell carcinoma (RCC) in Fabry disease (FD) is a rare event. We report a deep ultrastructural study of RCC in a patient with a previous histological diagnosis of FD. In order to highlight analogies and differences between the two histological samples, we used the nephrectomy specimen as a 'repeat biopsy', making a dynamic analysis of the evolution of the disease-related kidney damage. Secondly, a comparative ultrastructural analysis between non-neoplastic tissue and cancer demonstrated for the first time the presence of zebra bodies in the tumor cells. Finally, a hypothetical speculation about the relationship between the lysosomal accumulation, the oxidative damage and the genesis of the tumor was performed. The link connected the accumulation of glycosphingolipid globotriaosylceramide, characteristic of FD, with the expression of CD74 and macrophage migration inhibitory factor that may play an important role in tumorigenesis regulated by the Von Hippel-Lindau/hypoxia-inducible factor 1α pathway.

Multiplex Staining by Sequential Immunostaining and Antibody Removal on Routine Tissue Sections.

Multiplexing, labeling for multiple immunostains in the very same cell or tissue section in situ, has raised considerable interest. The methods proposed include the use of labeled primary antibodies, spectral separation of fluorochromes, bleaching of the fluorophores or chromogens, blocking of previous antibody layers, all in various combinations. The major obstacles to the diffusion of this technique are high costs in custom antibodies and instruments, low throughput, and scarcity of specialized skills or facilities. We have validated a method based on common primary and secondary antibodies and diffusely available fluorescent image scanners. It entails rounds of four-color indirect immunofluorescence, image acquisition, and removal (stripping) of the antibodies, before another stain is applied. The images are digitally registered and the autofluorescence is subtracted. Removal of antibodies is accomplished by disulfide cleavage and a detergent or by a chaotropic salt treatment, this latter followed by antigen refolding. More than 30 different antibody stains can be applied to one single section from routinely fixed and embedded tissue. This method requires a modest investment in hardware and materials and uses freeware image analysis software. Multiplexing on routine tissue sections is a high throughput tool for in situ characterization of neoplastic, reactive, inflammatory, and normal cells.

Peritoneal malignant mesothelioma metastatic to supraclavicular lymph nodes.

Distinguishing between malignant mesothelioma and reactive mesothelial hyperplasia is often inestimable, but may be a challenging gauntlet for pathologists. A 62-year-old man underwent appendectomy after the identification of a peritoneal mass and the histological examination showed mesothelial proliferation along the appendix surface with no clear images of infiltration. After a few months the patient developed mediastinal and supraclavicular lymphadenopathies, and a nodal biopsy showed mesothelial cell proliferation invading lymphatic sinuses, consistent with the cells seen in the abdominal cavity. Since overt morphologic criteria for malignancy were lacking and reactive mesothelial cell deposits have been documented in lymph nodes, a molecular investigation of the CDKN2A (henceforth simply p16) gene status via fluorescence in situ hybridization was performed, which showed homozygous deletion in 100% tumor cells. These data ruled out the hypothesis of reactive mesothelial cells inclusion in lymph nodes, thus confirming the diagnosis of epithelioid malignant mesothelioma.

HER2 status of gastric carcinoma and corresponding lymph node metastasis.

Our goal is to verify HER2 status variability between primary tumor and metastatic site. Our second intention is to identify the most reliable criteria for pathological HER2 status assessment in gastric cancer node metastases since, at present, there is not a validated standard. 3 independent pathologists evaluated HER2 immunohistochemical and gene status (for IHC 2+ cases) in 34 gastric carcinoma metastatic lymph nodes and in their corresponding primary tumors. For primary gastric cancers, we followed the current HER2 assessment guidelines and for nodal metastases, we applied two immunohistochemical scoring systems with different cut-offs. The immunohistochemical inter-pathologists mean agreement was 71.4 % (κ = 0.45); a final score for each case was defined after collegial revision. By applying the two immunohistochemical criteria, we found 2 discordant cases, which can imply different pathological management. Moreover, a significantly different HER2 status between lymph node metastasis and primary tumor was obtained in 4 cases (concordance ratio 87.5 %). None of the patients would have undergone a different therapeutic pathway despite the scoring method applied. On the other hand we also detected a subset of patients who could have their therapeutic management changed, according to the differences between HER2 status in lymph nodes metastases and primary tumor.