Exploring the molecular landscape of cutaneous mixed tumors characterized by TRPS1::PLAG1 gene fusion.

The histological similarities between pleomorphic adenomas (PAs) and cutaneous mixed tumors (CMTs) found in certain facial regions can create a diagnostic challenge. Molecular findings reveal common genetic profiles, particularly PLAG1 rearrangements in both PA and CMT. Although molecular distinctions have received limited attention, our observations indicate multiple cases of CMTs carrying the TRPS1::PLAG1 fusion.

Pustular mycosis fungoides has a poor outcome: a multicentric clinicopathological and molecular case series.

Background: Mycosis fungoides (MF) usually has an indolent course. However, some patients develop more aggressive disease and few prognostic parameters have been identified. Isolated cases of pustular MF (pMF) suggest an unfavourable prognosis.

Sweat Gland Tumors Arising on Acral Sites: A Molecular Survey.

Recurrent oncogenic drivers have been identified in a variety of sweat gland tumors. Recently, integration of human papillomavirus type 42 (HPV42) has been reported in digital papillary adenocarcinoma (DPA). The main objectives of the present study were (i) to provide an overview of the prevalence of previously identified oncogenic drivers in acral sweat gland tumors and (ii) to genetically characterize tumors in which no recurrent genetic alteration has been identified yet.

Brentuximab-vedotin in combination with cyclophosphamide, doxorubicin, prednisolone for the treatment of aggressive CD30-positive cutaneous T-cell lymphomas.

Aggressive CD30-positive cutaneous T-cell lymphomas (CD30CTCL) are associated with unfavorable prognosis. Anthracycline-based polychemotherapy (CHOP) and brentuximab-vedotin (BV) monotherapy are related to poor outcomes in case of extracutaneous involvement or rapidly-progressing disease. Our objective was to assess the effectiveness of BV + CHP in aggressive CD30CTCL.

Deciphering the spectrum of cutaneous lymphomas expressing TFH markers.

T-follicular helper (TFH) markers are expressed in the microenvironnement of marginal zone B-cell lymphoma (MZL), and in lymphomas arising from TFH-cells, sometimes making the differential diagnosis difficult. In the skin, the "TFH-spectrum" is poorly defined, going from primary cutaneous lymphoproliferative disorder with small/medium CD4+ T-cells (SMLPD) to cutaneous localizations of systemic angioimmunoblastic T-cell lymphoma (cAITL), and may pass through intermediate forms (primary cutaneous T-follicular helper derived lymphoma, not otherwise specified (PCTFHL,NOS)). We retrospectively analyzed 20 MZL, 13 SMLPD, 5 PCTFHL, and 11 cAITL clinically, histologically, and molecularly, to define tools to differentiate them.

Distinct regulations driving YAP1 expression loss in poroma, porocarcinoma and RB1-deficient skin carcinoma.

Aims: Recently, YAP1 fusion genes have been demonstrated in eccrine poroma and porocarcinoma, and the diagnostic use of YAP1 immunohistochemistry has been highlighted in this setting. In other organs, loss of YAP1 expression can reflect YAP1 rearrangement or transcriptional repression, notably through RB1 inactivation. In this context, our objective was to re-evaluate the performance of YAP1 immunohistochemistry for the diagnosis of poroma and porocarcinoma.

Necrobiosis lipoidica of the breast associated with Crohn's disease: a case report.

Background: Necrobiosis lipoidica located to the breast; without evidence of glucose intolerance, is extremely rare, and its association to Crohn's disease is not usual.

Case Presentation: We report an interesting case of an association of necrobiosis lipoidica of the breast and Crohn's disease in a 54-year-old Moroccan woman. Skin necrobiotic changes are a characteristic feature in necrobiosis lipoidica, but they are exceptional in metastatic Crohn's disease, since there are only three published cases of necrobiotic skin lesions on the lower leg resembling erythema nodosum in metastatic Crohn's disease.

[A particular presentation of a T cell large granular lymphocytic leukaemia].

T cell prolymphocytic leukemia (T-PLL) is a rare, aggressive neoplasm derived from post-thymic T cells. Patients are typically middle-aged with a slight male predominance who present with a high white blood cell count, hepatosplenomegaly, lymphadenopathy, and other symptoms typically associated with leukemia. Although cutaneous involvement has been reported in up to 30% of cases of T-PLL, to our knowledge, none have presented with a presentation resembling livedoid vasculopathy.

Improved NGS-based detection of microsatellite instability using tumor-only data.

Microsatellite instability (MSI) is a molecular signature of mismatch repair deficiency (dMMR), a predictive marker of immune checkpoint inhibitor therapy response. Despite its recognized pan-cancer value, most methods only support detection of this signature in colorectal cancer. In addition to the tissue-specific differences that impact the sensitivity of MSI detection in other tissues, the performance of most methods is also affected by patient ethnicity, tumor content, and other sample-specific properties.

[Rosai-Dorfman-Destombes disease with a misleading laryngeal presentation].

Rosai-Dorfman-Destombes disease is a rare non-Langerhansian cell histiocytosis characterized by the accumulation of large activated histiocytes in the affected tissues with images of emperipolesis. The diagnosis is not really problematic in the classical forms, with a lymph node presentation, whose histology is very suggestive. However, it can be much more difficult in the extra-nodal forms, which are misleading in both their clinical and histological presentation.

Primary cutaneous peripheral T-cell lymphomas with a T-follicular helper phenotype: an integrative clinical, pathological and molecular case series study.

Background: Primary cutaneous peripheral T-cell lymphomas with a T-follicular helper phenotype (pcTFH-PTCL) are poorly characterized, and often compared to, but not corresponding with, mycosis fungoides (MF), Sézary syndrome, primary cutaneous CD4 lymphoproliferative disorder, and skin manifestations of angioimmunoblastic T-cell lymphomas (AITL).

Objectives: We describe the clinicopathological features of pcTFH-PTCL in this original series of 23 patients, and also characterize these cases molecularly.

Methods: Clinical and histopathological data of the selected patients were reviewed.

Harmonization of programmed death-ligand 1 immunohistochemistry and mRNA expression scoring in metastatic melanoma: a multicentre analysis.

Aims: The aim of this multicentre study was to harmonize programmed death-ligand 1 (PD-L1) immunohistochemistry (IHC) and melanoma scoring. To provide a reference for PD-L1 expression independently of the IHC protocol, PD-L1 mRNA expression was compared with IHC.

Methods And Results: Standardized PD-L1 assays (22C3, 28-8, SP142, SP263) and laboratory-developed tests (QR1, 22C3) were evaluated on three IHC platforms with a training set (seven cases).

ZEB1 transcription factor promotes immune escape in melanoma.

Background: The efficacy of immunotherapies in metastatic melanoma depends on a robust T cell infiltration. Oncogenic alterations of tumor cells have been associated to T cell exclusion. Identifying novel cancer cell-intrinsic non-genetic mechanisms of immune escape, the targeting of which would reinstate T cell recruitment, would allow to restore the response to anti-programmed cell death protein 1 (PD-1) antibody therapy.

Impact of expert pathology review in skin adnexal carcinoma diagnosis: Analysis of 2573 patients from the French CARADERM network.

Purpose: To prospectively assess the impact of expert pathological review of skin adnexal carcinoma diagnosis in France.

Methods: From 2014 to 2019, 2573 samples from patients with newly diagnosed or suspected skin adnexal carcinomas were reviewed prospectively by expert pathologists through the national CARADERM (CAncers RAres DERMatologiques) network. Changes in diagnosis between referral and expert review were analysed regarding their potential impact on patient care or prognosis.

Recurrent FOXK1::GRHL and GPS2::GRHL fusions in trichogerminoma.

We report 21 cases of trichogerminoma harbouring previously undescribed FOXK1::GRHL1/2 or GPS2::GRHL1/2/3 in-frame fusion transcripts. Microscopic examination of a preliminary set of five cases revealed well-delimitated tumours located in the dermis with frequent extension to the subcutaneous tissue. Tumours presented a massive and nodular architecture and consisted of a proliferation of basaloid cells.

Plasticity of Mature B Cells Between Follicular and Classic Hodgkin Lymphomas: A Series of 22 Cases Expanding the Spectrum of Transdifferentiation.

Follicular lymphoma and classic Hodgkin lymphoma can be associated in composite and/or sequential lymphomas. Common IGH and BCL2 rearrangements have already been identified between both contingents of these entities, but mutation profiles have not yet been investigated. The main objective of this study was to analyze the transdifferentiation process that may occur between Hodgkin and follicular contingents in sequential and composite lymphomas to better characterize these entities.