Revealing loss in an emerging entity: report of two cases of PRRX1-rearranged mesenchymal tumours.

Aims: -rearranged mesenchymal tumours are a recently identified and rare subgroup of soft tissue neoplasms with distinct morphological features and genetic alterations. This study aims to further investigate the immunohistochemical profile and underlying genetic alterations in these tumours in order to get more insight on their underlying biology and the unique profile of these tumours.

Methods: Two new molecular confirmed cases of -rearranged mesenchymal tumours were thoroughly studied with immunohistochemical stainings (RB1, CD34, ALK and pan-TRK), fluorescence in situ hybridisation (FISH) and RNA-based next-generation sequencing.

Clear Cell Proliferations of the Skin: A Histopathologic Review.

Cutaneous clear cell proliferations encompass a heterogenous group of several primary cutaneous neoplasms and metastatic tumors with different histogenesis. Many of these clear cell proliferations may seem strikingly similar under the microscope resulting in challenging diagnosis. In many of these clear cell lesions, the reason for the clear or pale appearance of proliferating cells is unknown, whereas in other ones, this clear cell appearance is due to intracytoplasmic accumulation of glycogen, mucin, or lipid.

Development of a 3D pigmented skin model to evaluate RNAi-induced depigmentation.

Because current skin whitening agents often have insufficient efficacy and side effects, we aim to develop effective and safe therapeutics using RNA interference (RNAi). We established a pigmented human-reconstructed skin model as a first step in the development of novel siRNA-based depigmenting agents. Histological characterization revealed that our model had a similar morphology as normal human skin, expressed keratinocyte differentiation as well as basement membrane markers, and showed a high degree of pigmentation.

Laryngeal zoster with multiple cranial nerve palsies.

A young immunocompetent patient is presented with a very rare presentation of a common viral illness: herpes zoster of the left hemilarynx with sensorial and motoric neuropathy of three ipsilateral lower cranial nerves: IX, X and XI. The mucosal lesions were discovered during upper gastrointestinal endoscopy. PCR of erosional exsudate confirmed the clinical diagnosis.

The quest for the mechanism of melanin transfer.

Skin pigmentation is accomplished by production of melanin in specialized membrane-bound organelles termed melanosomes and by transfer of these organelles from melanocytes to surrounding keratinocytes. The mechanism by which these cells transfer melanin is yet unknown. A central role has been established for the protease-activated receptor-2 of the keratinocyte which effectuates melanin transfer via phagocytosis.

P-cadherin promotes cell-cell adhesion and counteracts invasion in human melanoma.

Malignant transformation of melanocytes frequently coincides with alterations in epithelial cadherin (E-cadherin) expression, switching on of neural cadherin (N-cadherin), and, when progressed to a metastatic stage, loss of membranous placental cadherin (P-cadherin). In vitro studies of melanoma cell lines have shown invasion suppressor and promoter roles for E-cadherin and N-cadherin, respectively. In the present study, we investigated the effect of P-cadherin on aggregation and invasion using melanoma cells retrovirally transduced with human P-cadherin.

Different approaches for assaying melanosome transfer.

Many approaches have been tried to establish assays for melanosome transfer to keratinocytes. In this report, we describe and summarize various novel attempts to label melanosomes in search of a reliable, specific, reproducible and quantitative assay system. We tried to fluorescently label melanosomes by transfection of GFP-labeled melanosomal proteins and by incubation of melanocytes with fluorescent melanin intermediates or homologues.

Rab27b is up-regulated in human Griscelli syndrome type II melanocytes and linked to the actin cytoskeleton via exon F-Myosin Va transcripts.

Patients with the autosomal recessive Griscelli-Pruniéras syndrome type II are immunologically impaired and have an unusual silvery-grey hypopigmented colour of scalp hair, eyelashes and eyebrows but no noteworthy pigmentary abnormalities of the skin. In most Griscelli patients, the RAB27A gene, which encodes a small GTPase that is associated with the melanosome membrane in melanocytes, is mutated. Here we discuss a genomic RAB27A deletion found in a 21-month-old Moroccan Griscelli patient.