Search

PRAME (PReferentially expressed Antigen in MElanoma) is a tumor-associated antigen that was recently found to be expressed by malignant melanocytic lesions but not by benign ones, thus resulting useful in this diagnostic field. PRAME could also be expressed by some normal tissues and nonmelanocytic tumors, suggesting as caution should be adopted to use PRAME as a "pan-melanoma" marker for the differential diagnosis with other malignant tumors. Until now, PRAME expression was exclusively investigated through single staining with a monoclonal antibody targeting PRAME and with double staining for Melan A/PRAME found to be useful in specific diagnostic sets. Herein, we studied the expression of PRAME in 40 melanocytic lesions and 23 nonmelanocytic ones using PRAME, Melan A/PRAME, and novel double staining for HMB45/PRAME. Although our results need to be validated, they support the adoption of HMB45/PRAME, alone or in combination with PRAME and Melan A/PRAME, as a helpful marker in the diagnosis of melanocytic neoplasms with a high concordance rate between primary melanoma and corresponding metastases.

The collaborative Cancer Genome Atlas (TCGA) project identified four distinct prognostic groups of endometrial carcinoma (EC) based on molecular alterations: (i) the ultramutated subtype that encompasses POLE mutated (POLE) cases, (ii) the hypermutated subtype, characterized by MisMatch Repair deficiency (MMRd), (iii) the copy-number high subtype, with p53 abnormal/mutated features (p53abn), (iv) the copy-number low subtype, known as No Specific Molecular Profile (NSMP). Although the prognostic value of TCGA molecular classification, NSMP carcinomas present a wide variability in molecular alterations and biological aggressiveness. This study aims to investigate the impact of ARID1A and CTNNB1/β-catenin alterations by targeted Next-generation sequencing (NGS) and immunohistochemistry (IHC) in a consecutive series of 125 molecularly classified ECs. NGS and IHC were used to assign surrogate TCGA groups and to identify molecular alterations of multiple target genes including POLE, PTEN, ARID1A, CTNNB1, TP53. Associations with clinicopathologic parameters, molecular subtypes, and outcomes identified NSMP category as the most heterogeneous group in terms of clinicopathologic features and outcome. Integration of surrogate TCGA molecular classification with ARID1A and β-catenin analysis showed NSMP cases with ARID1A mutation characterized by the worst outcome with early recurrence, while NSMP tumors with ARID1A wild-type and β-catenin alteration had indolent clinicopathologic features and no recurrence. This study indicates how the identification of ARID1A and β-catenin alterations in EC represents a simple and effective way to characterize NSMP tumor aggressiveness and metastatic potential.

A 9-month old male Jack Russell Terrier started showing paraparesis of the hindlimbs after a walk. Hospitalized, the dog went into cardiac arrest, and later died. Necroscopic examination revealed a severe thickness of the diaphragm, esophagus, and base of the tongue, leading to the diagnosis of muscular dystrophy. The histology confirmed the marked size variation, regeneration, and fibrosis replacement of the skeletal muscle fibers. Immunohistochemistry demonstrated the absence of dystrophin confirming the diagnosis. Transmission electron microscopy showed disarrangement of skeletal muscle fibers. Finally, whole-genome sequencing identified a ~368kb deletion spanning 19 exons of the canine dystrophin (DMD) gene. This pathogenic loss-of-function variant most likely explains the observed disease phenotype. The X-chromosomal variant was absent in seven controls of the same breed. Most likely, this partial deletion of the DMD gene was either transmitted on the maternal path within the family of the affected dog or arose de novo. This study revealed a spontaneous partial deletion in DMD gene in a Jack Russell Terrier showing a Duchenne-type muscular dystrophy due to non-functional dystrophin.

Melanoma in giant congenital nevus (M-GCN) is a rare and potentially lethal neoplasm. In children, M-GCN appears as a dermal/deep-seated melanoma (DDM-GCN) with histopathologic features difficult to distinguish from proliferative nodules (PNs-GCN). DDM-GCN in adults is an anecdotal entity and only 8 cases have been described and genetically characterized. We report the first case of DDM-GCN in a 34-year-old man characterized with a large-panel next-generation sequence (NGS) highlighting a TP53 mutation with a UV-signature (C>T substitution) in DDM but not in PNs-GCN and GCN. Curiously, DDM showed an aberrant p16 overexpression without detection of CDKN2A mutation at NGS. In line with previous studies, it supports a different pathway in children and adults: UV-induced mutations may be involved in the latter not only by CDKN2A but also by TP53 mutations, with a potentially confusing overexpression of p16 protein. While these data need to be confirmed in larger cases series, our results show that NGS could be an additional genetic diagnostic tool in DDM-GCN.

We have investigated the morphology of the sinus node of the human cardiac conduction system. Until today the sinus node (SN) is described as a heterogeneous system composed of 2 types of cells, namely, P or pale and T or transitional cells which are immersed in the matrix around the sinus nodal artery. T cells are said to share characteristics of P cells and of peripheral working atrial myocardial cells. This study was carried out on autoptic and explanted specimens using histochemical, immunohistochemical, and electron microscopic methods.Our investigations show that SN tissue has a quite different cellular composition, ie, spherical and/or star-shaped cells organized in clusters with long cytoplasmic processes (type P), transitional cells, similar to myocytes but with a reduced number of sarcomeres (type T) and, finally, as yet not described in the literature, fibroblast-like cells with long bi-tripolar extensions contacting cells. Interestingly, SN is squared by connective and elastic fibers geometrically arranged. Immunohistochemistry shows that the 3 cell types of the SN node express mesenchymal markers revelatory of their embryological origin. Innervation appears to be more complex than previously thought; we identified a system of synaptophysin-positive cholinergic vesicles dependent on the sympathetic system and parasympathetic fibers expressing S100 protein.Overall results indicate that the SN has an unexpected, systematic architecture.