[Clinical, histological and genetic correlations in melanocytic tumours with chromosomal rearrangements]. / Corrélations cliniques, morphologiques et génétiques dans les tumeurs mélanocytaires avec translocations chromosomiques.

In some tumoral subtypes chromosomal translocations lead to an oncogenic chimeric protein acting as a tumorigenesis driver event. The main fusion model combines the promoter swapping of an inactivated tumor suppressor gene and a functional kinase that evades its regulatory system. The range of described fusions keeps growing in the 2023 WHO classification of melanocytic tumours. It is not limited to the group of Spitz tumours as previously but now extends to blue tumours and dermal tumours with a melanocytic phenotype. Molecular pathology helps detect these anomalies using clinical and morphological features. This analysis is essential as this strongly conditions the adapted local treatment of such tumours who are often overtreated.

[A curious biphasic breast lesion]. / Une curieuse lésion biphasique du sein.

Adenomyoepithelioma represents 0.5% of breast tumors in postmenauposal women. Prognosis is good when the tumor is benign. However, its malignant variant is associated with a poor prognosis with local recurrences and metastatic potential. We present the case of a malignant adenomyoepithelioma, expose the 2019 WHO classification issues and propose a classification in three categories: benign, atypical and malignant adenomyoepitheliomas (in situ and invasive).

T cell phenotype and lack of eosinophilia are not uncommon in extramedullary myeloid/lymphoid neoplasms with ETV6::FLT3 fusion: a case report and review of the literature.

In the 2022, WHO and ICC classifications, myeloid/lymphoid neoplasms with eosinophilia (M/LN-eo) and tyrosine kinase gene fusions represent rare hematologic malignancies driven by rearrangements of PDGFRA, PDGFRB, FGFR1, JAK2, FLT3, and ETV6::ABL1 fusion. Eosinophilia is the most constant finding, whereas the clinicopathological features are quite heterogeneous, presenting as Chronic eosinophilic leukemia (CEL) NOS, myelodysplastic/myeloproliferative neoplasm (MDS/MPN), MDS, MPN, systemic mastocytosis (SM), T or B cell acute lymphoblastic leukemia/lymphoblastic lymphoma (ALL/LBL), acute myeloid leukemia (AML), blastic phase of MPN, or mixed phenotype acute leukemia (MPAL). Extramedullary involvement at diagnosis or during progression is common. Here, we report a very unusual case of myeloid/lymphoid neoplasm with ETV6::FLT3 fusion with a nodal presentation without associated eosinophilia. Our case draws attention to diagnostic pitfalls in these rare entities.