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Somatic variant testing through next-generation sequencing (NGS) is well integrated into Swiss molecular pathology laboratories and has become a standard diagnostic method for numerous indications in cancer patient care. Currently, there is a wide variation in reporting practices within our country, and as patients move between different hospitals, it is increasingly necessary to standardize NGS reports to ease their reinterpretation. Additionally, as many different stakeholders-oncologists, hematologists, geneticists, pathologists, and patients-have access to the NGS report, it needs to contain comprehensive and detailed information in order to answer the questions of experts and avoid misinterpretation by non-experts. In 2017, the Swiss Institute of Bioinformatics conducted a survey to assess the differences in NGS reporting practices across ten pathology institutes in Switzerland. The survey examined 68 reporting items and identified 48 discrepancies. Based on these findings, the Swiss Society of Molecular Pathology initiated a Delphi method to reach a consensus on a set of recommendations for NGS reporting. Reports should include clinical information about the patient and the diagnosis, technical details about the sample and the test performed, and a list of all clinically relevant variants and variants of uncertain significance. In the absence of a consensus on an actionability scheme, the five-class pathogenicity scheme proposed by the ACMG/AMP guideline must be included in the reports. The Swiss Society of Molecular Pathology recognizes the importance of including clinical actionability in the report and calls on the European community of molecular pathologists and oncologists to reach a consensus on this issue., (© 2024. The Author(s).)

Intravascular large B-cell lymphoma is a rare and aggressive EBV-negative large B-cell lymphoma with a dismal outcome. Here, we describe the case of a 76-year-old HIV-positive patient with an acute presentation of systemic symptoms and rapidly fatal outcome. Autopsy revealed a disseminated large B-cell lymphoma with an intravascular distribution involving the liver, lymph nodes, spleen, and bone marrow and associated to fibrin thrombi in hepatic capillary haemangiomas. The neoplastic B cells (CD79a + / - , CD20 + / - , CD30 + , MUM1 + , PD-L1 +) showed a Hodgkin and Reed-Sternberg-like morphology and were EBV-positive with a latency type II (LMP1 + , EBNA2-). Haemophagocytosis was documented in the bone marrow and lymph nodes. This case illustrates the diagnostic challenges of large B-cell lymphoma with intravascular presentation. We found only five other cases of EBV-positive large B-cell lymphoma with an intravascular presentation in the literature, three of which had an underlying immunodeficiency adding to the broad spectrum of EBV-associated lymphoma in the setting of immunosuppression., (© 2021. The Author(s).)

Acinar cell carcinomas (ACCs) of the pancreas are a heterogeneous group of neoplasms showing a wide spectrum of morphological features including acinar, solid, glandular, and trabecular architecture. In addition, uncommon cytological aspects have recently been described and include oncocytic, spindle, clear, and pleomorphic cell types. This wide histological spectrum represents a challenge in the diagnostic task for pathologists. Molecular mechanisms involved in the onset and progression of ACCs are not completely known, but, in general, they differ from those observed in ductal adenocarcinomas or neuroendocrine neoplasms of the pancreas and frequently include alterations in the APC/β-catenin pathway. In the present paper, we describe a new variant of ACC showing thyroid-like follicular features and CTNNB1 mutation. This phenotype needs to be included in the spectrum of morphological presentation of ACC.

B-cell lymphomas encompass a large number of disease entities clinically ranging from indolent to aggressive. The defining pathological features usually predict clinical course, with small and large B-cell lymphomas correlating to low-grade vs high-grade features, but discordant situations may be encountered. Two sessions of the workshop of the XVIII meeting of the European Association for Haematopathology (EAHP) held in Basel in 2016 addressed this topic. One session illustrated various facets of "aggressiveness" in indolent lymphomas, either peculiar clinical manifestations, cytological variants, or unusual genetic features, as well as several examples of progression or transformation to a more aggressive disease. Another session exemplified large B-cell lymphomas with unexpected indolent behavior including cases arising in well-defined body compartments or in sanctuary sites. This paper describes the features of the cases presented in both groups, highlights the most salient points of discussion raised by the submitters and the panel, and summarizes current knowledge and recommendations relevant to diagnostic pathology practice.

T cell lymphoma of γδ T cell origin is a rare disease that mainly involves extranodal sites and shows aggressive clinical behavior. Here, we report a case of primary γδ T cell lymphoma of the lungs with epitheliotropism in the respiratory epithelium, a feature somewhat reminiscent of what is observed in enteropathy-associated T cell lymphoma. A 63-year-old man presented with chest pain and dyspnea on exertion, weight loss, and general weakness. On a positron emission tomography (PET) scan, multiple hypermetabolic lesions were found in both lungs. Microscopic examination of the wedge lung biopsy revealed nodular infiltration of monomorphic, medium- to large-sized atypical lymphocytes with round nuclei, coarse chromatin, and a variable amount of clear to eosinophilic cytoplasm. Of note, intraepithelial lymphocytosis by atypical lymphoid cells was observed in the respiratory epithelium within and around the nodule. Immunohistochemically, the tumor cells were CD3+, TCRβF1-, TCRγ+, CD5-, CD7+, CD20-, CD79a-, CD30-, CD4-, CD8-, CD10-, BCL6-, CD21-, CD56+, CD57-, and CD138-, and expressed cytotoxic molecules. Epstein-Barr virus (EBV) was not detected by an in situ hybridization assay for EBV-encoded RNA. Interestingly, CD103 was expressed by a subset of tumor cells, especially those infiltrating the epithelium. T cell clonality was detected by multiplex PCR analysis of TRG and TRD gene rearrangements. After 2 months of systemic chemotherapy, PET scan showed regression of the size and metabolic activity of the lesions. This case represents a unique γδ T cell lymphoma of the lungs showing epitheliotropism by CD103+ γδ T cells that is suggestive of tissue-resident γδ T cells as the cell of origin.

Recurrent chromosomal translocations associated to peripheral T-cell lymphomas (PTCL) are rare. Here, we report a case of PTCL, not otherwise specified (NOS) with the karyotype 46,Y,add(X)(p22),t(6;14)(p25;q11) and FISH-proved breakpoints in the IRF4 and TCRAD loci, leading to juxtaposition of both genes. A 64-year-old male patient presented with mild cytopenias and massive splenomegaly. Splenectomy showed diffuse red pulp involvement by a pleomorphic medium- to large-cell T-cell lymphoma with a CD2+ CD3+ CD5- CD7- CD4+ CD8+/- CD30- TCRbeta-F1+ immunophenotype, an activated cytotoxic profile, and strong MUM1 expression. The clinical course was marked by disease progression in the bone marrow under treatment and death at 4 months. In contrast with two t(6;14)(p25;q11.2)-positive lymphomas previously reported to be cytotoxic PTCL, NOS with bone marrow and skin involvement, this case was manifested by massive splenomegaly, expanding the clinical spectrum of PTCLs harboring t(6;14)(p25;q11.2) and supporting consideration of this translocation as a marker of biological aggressiveness.