Histopathological features of human mpox: Report of two cases and review of the literature.

Human monkeypox is an emerging zoonosis with epidemic potential. Although it usually causes a mild disease, some patients are at risk for complications, including death. In face of the current outbreak of monkeypox in non-endemic areas, awareness is paramount to diagnose it timely, prompting an early break of the transmission chain. Histopathologic findings in vesiculopustular lesions of monkeypox are distinctive, consisting of ballooning and reticular degeneration of keratinocytes, necrosis, especially of the upper portions of the epithelium, multinucleation of keratinocytes, nuclear enlargement showing a "basophilic halo" around a "ground glass" eosinophilic center, the orthopoxvirus-specific cytoplasmic eosinophilic Guarnieri-type inclusions (in the pustular stage especially), and a dense mixed inflammatory cell infiltrate with prominent neutrophil exocytosis. The diagnosis of human monkeypox requires a high index of suspicion. In correlation with clinical information, histopathological findings allow for a presumptive diagnosis of monkeypox if polymerase chain reaction testing is not available. Both clinicians and pathologists can optimize diagnostic sensitivity, respectively, by considering the epidemiological context, sampling pustular lesions and providing data for clinicopathological correlation, and by intentionally searching the tell-tale eosinophilic inclusions in genital, anal and oral lesions with reticular and ballooning degenerescence.

Quantitative Determination of Water in Organic Liquids by Ambient Mass Spectrometry.

This study uses a rapid tandem mass-spectrometry method to determine water content in complex organic solutions. Emphasis is placed on trace-water analysis by a fast and accurate alternative to the Karl-Fischer method. In this new method, water is captured by a charge-labeled molecular probe. Water binds strongly with high specificity to the strongly electrophilic aldehyde site in a charge-labelled molecule (N-methylpyridinium); competitive binding by other analytes is effectively discriminated against in the mass-measurement step. Quantitative determinations are made over a wide concentration range, 0.001 % (10 ppm) to 99 %, with better than 10 % relative standard deviation, along with short (1 min) analysis times using small sample volumes (several µL). Applications include water measurement in simple organic solvents, for example, deuterated solvents, as well as in complex mixtures, for example, organic reaction mixtures. Additionally, this method allows for water monitoring in levitated droplets. Mechanistic investigations into the impact of water on important chemical processes in organic synthesis and environmental science are reported.

Multiple Immunostainings with Different Epitope Retrievals-The FOLGAS Protocol.

We describe a sequential multistaining protocol for immunohistochemistry, immunofluorescence and CyTOF imaging for formalin-fixed, paraffin-embedded specimens (FFPE) in the formalin gas-phase (FOLGAS), enabling sequential multistaining, independent from the primary and secondary antibodies and retrieval. Histomorphologic details are preserved, and crossreactivity and loss of signal intensity are not detectable. Combined with a DAB-based hydrophobic masking of metal-labeled primary antibodies, FOLGAS allows the extended use of CyTOF imaging in FFPE sections.

High Numbers and Densities of PD1+ T-Follicular Helper Cells in Triple-Negative Breast Cancer Draining Lymph Nodes Are Associated with Lower Survival.

Breast cancer tumor draining lymph nodes (TDLNs) display distinct morphologic changes depending on the breast cancer subtype. For triple-negative breast cancers (TNBC), draining LNs display a higher amount of secondary lymphoid follicles, which can be regarded as a surrogate marker for an activated humoral immune response. In the present study, we focus on PD1+ T-follicular helper cells (Tfh) in TDLNs of TNBC, since PD1+ Tfh are drivers of the germinal center (GC) reaction. We quantified PD1+ Tfh in 22 sentinel LNs with 853 GCs and interfollicular areas from 19 patients with TNBC by morphometry from digitalized immunostained tissue sections. Overall survival was significantly worse for patients with a higher number and area density of PD1+ Tfh within GCs of TDLNs. Further, we performed T-cell receptor gamma chain (TRG) analysis from microdissected tissue in the primary tumor and TDLNs. Eleven patients showed the same TRG clones in the tumor and the LN. Five patients shared the same TRG clones in the tumor and the GCs. In two patients, those clones were highly enriched inside the GCs. Enrichment of identical TRG clones at the tumor site vs. the TDLN was associated with improved overall survival. TDLNs are important relays of cancer immunity and enable surrogate approaches to predict the outcome of TNBC itself.

Angiotropism in primary cutaneous melanoma is associated with disease progression and distant metastases: A retrospective study of 179 cases.

BACKGROUND: Angiotropism is the histopathological correlate of pericytic mimicry and extravascular migratory metastasis (EVMM), a mechanism of melanoma spread by migration along the external surface of blood and lymphatic vessels. The frequency of angiotropism in primary cutaneous melanoma and the clinical utility of its detection remain unclear. METHODS: We investigated angiotropism in 179 primary cutaneous melanomas by hematoxylin and eosin (H&E), CD31, and S100/D240 stains. RESULTS: We detected angiotropism in 31 cases (17%) by H&E. CD31 immunohistochemistry increased detection to 59 cases (33%). When lymphatic vessels were included by using S100/D240 stains, 67 cases (37%) cases were positive. Angiotropism was associated with lymphatic invasion and mitotic rate with all detection methods. There was an association with increased tumor thickness when detected by H&E and CD31. No association with sentinel lymph node status was seen. By H&E and CD31 staining, angiotropism was associated with disease progression and distant metastases by univariate, but not multivariate analysis. Overall survival was not affected by the presence of angiotropism. CONCLUSIONS: Angiotropism is relatively common in primary melanoma when immunohistochemical stains are used for detection and associated with mitotic rate and intravascular lymphatic invasion. The association with disease progression and distant metastasis suggests that it represents an alternative pathway of metastasis, that is, EVMM/pericytic mimicry vs intravascular spread.

New developments in FcepsilonRI regulation, function and inhibition.

The high-affinity Fc receptor for IgE (FcepsilonRI), a multimeric immune receptor, is a crucial structure for IgE-mediated allergic reactions. In recent years, advances have been made in several important areas of the study of FcepsilonRI. The first area relates to FcepsilonRI-mediated biological responses that are antigen independent. The second area encompasses the biological relevance of the distinct signalling pathways that are activated by FcepsilonRI; and the third area relates to the accumulated evidence for the tight control of FcepsilonRI signalling through a broad array of inhibitory mechanisms, which are being developed into promising therapeutic approaches.

Recent Advances in Asymmetric Hydrogenation of Tetrasubstituted Olefins.

The asymmetric hydrogenation of tetrasubstituted olefins provides direct access to very useful biological molecules and intermediates. The development of the technology has been slow, due in part to the synthetic challenges involved in developing chiral catalysts for a successful asymmetric induction. We briefly recount the breakthroughs in functionalized and unfunctionalized tetrasubstituted olefins, from the reports of Zhou and Buchwald for functionalized and unfunctionalized substrates, respectively, to the advent of chiral phosphoramidite ligands. The main emphasis of this Perspective lies in bringing into focus the complexity and challenges of inducing an asymmetric reduction for these substrates, which includes a brief discussion of the mechanism, the latest developed chiral catalysts, and the enormous scientific opportunities that still exist in developing "go to" catalyst systems for the various substrate types.

Lymphatic invasion and angiotropism in primary cutaneous melanoma.

Access of melanoma cells to the cutaneous vasculature either via lymphatic invasion or angiotropism is a proposed mechanism for metastasis. Lymphatic invasion is believed to be a mechanism by which melanoma cells can disseminate to regional lymph nodes and to distant sites and may be predictive of adverse outcomes. Although it can be detected on hematoxylin- and eosin-stained sections, sensitivity is markedly improved by immunohistochemistry for lymphatic endothelial cells. Multiple studies have reported a significant association between the presence of lymphatic invasion and sentinel lymph node metastasis and survival. More recently, extravascular migratory metastasis has been suggested as another means by which melanoma cells can spread. Angiotropism, the histopathologic correlate of extravascular migratory metastasis, has also been associated with melanoma metastasis and disease recurrence. Although lymphatic invasion and angiotropism are not currently part of routine melanoma reporting, the detection of these attributes using ancillary immunohistochemical stains may be useful in therapeutic planning for patients with melanoma.

Melanoma subtypes demonstrate distinct PD-L1 expression profiles.

PD-L1 expression in the tumor immune microenvironment is recognized as both a prognostic and predictive biomarker in patients with cutaneous melanoma, a finding closely related to its adaptive (IFN-γ-mediated) mechanism of expression. Approximately 35% of cutaneous melanomas express PD-L1, however, the expression patterns, levels, and prevalence in rarer melanoma subtypes are not well described. We performed immunohistochemistry for PD-L1 and CD8 on 200 formalin-fixed paraffin-embedded specimens from patients with acral (n=16), mucosal (n=36), uveal (n=103), and chronic sun-damaged (CSD) (n=45) melanomas (24 lentigo maligna, 13 'mixed' desmoplastic, and 8 'pure' desmoplastic melanomas). CD8+ tumor-infiltrating lymphocyte (TIL) densities were characterized as mild, moderate, or severe, and their geographic association with PD-L1 expression was evaluated. Discrete lymphoid aggregates, the presence of a spindle cell morphology, and the relationship of these features with PD-L1 expression were assessed. PD-L1 expression was observed in 31% of acral melanomas, 44% of mucosal melanomas, 10% of uveal melanomas, and 62% of CSD melanomas (P<0.0001). Compared to our previously characterized cohort of cutaneous melanomas, the proportion of PD-L1(+) tumors was lower in uveal (P=0.0002) and higher in CSD (P=0.0073) melanomas, while PD-L1 expression in the acral and mucosal subtypes was on par. PD-L1 expression in all subtypes correlated with a moderate-severe grade of CD8+ TIL (all, P<0.003), supporting an adaptive mechanism of expression induced during the host antitumor response. The tumor microenvironments observed in CSD melanomas segregated by whether they were the pure desmoplastic subtype, which showed lower levels of PD-L1 expression when compared to other CSD melanomas (P=0.047). The presence of lymphoid aggregates was not associated with the level of PD-L1 expression, while PD-L1(+) cases with spindle cell morphology demonstrated higher levels of PD-L1 than those with a nested phenotype (P<0.0001). Our findings may underpin the reported clinical response rates for anti-PD-1 monotherapy, which vary by subtype.

PDL1 expression in desmoplastic melanoma is associated with tumor aggressiveness and progression.

BACKGROUND: The prognostic role of programmed death ligand 1 (PDL1), CD8, and forkhead box p3 (FoxP3) expression in desmoplastic melanomas is unclear. METHODS: We correlated PDL1, p53, and Ki-67 expression with CD8+ and FoxP3+ immune infiltrates with clinicopathologic variables and patient outcomes in a series of 66 desmoplastic melanomas. RESULTS: Tumoral PDL1 expression (≥25%), which was seen in 21% of patients (14 of 66), significantly correlated with mixed histology, tumor thickness, mitoses, recurrence, and metastasis. According to linear regression analysis, tumoral PDL1 expression correlated with thickness (P = .0041); p53 expression (P = .019); Ki-67 proliferation index (P = .0018); and tumoral CD8 (P = .0084), stromal CD8 (P < .0001), and FoxP3 (P < .0001) T-cell counts. According to univariate analyses, PDL1 expression of 25% or higher correlated with shorter progression-free survival (P < .0001) and melanoma-specific survival (P = .034). According to multivariate analyses, PDL1 expression of 25% or more (P = .026) and mixed histology (P = .039) independently predicted shorter progression-free survival, and presence of lymphovascular invasion predicted shorter overall survival (P = .018). LIMITATIONS: Small study size. CONCLUSION: Tumoral and stromal CD8+ and FoxP3+ lymphocyte counts correlated with tumoral PDL1 expression, which is supportive of an adaptive immune response. PDL1 expression in desmoplastic melanoma was associated with tumor aggressiveness and progression. Although PDL1 expression is typically low in melanoma, its frequency and level of expression in desmoplastic melanoma may identify a subset of melanomas that are likely to respond to immunotherapy.

Lymphatic invasion predicts sentinel lymph node metastasis and adverse outcome in primary cutaneous melanoma.

BACKGROUND: Sentinel lymph node (SLN) metastasis is a powerful predictor of survival in primary cutaneous melanoma. Lymphatic invasion (LI) may correlate with increased risk of SLN metastasis. Intralymphatic metastases, often difficult to detect on hematoxylin and eosin (H&E) stained sections, are readily identified with dual immunohistochemistry for melanocytic and lymphatic markers. METHODS: We used dual S100/D240 immunohistochemistry to detect LI in 125 melanomas from patients who underwent SLN biopsy and correlated LI with melanoma staging parameters and disease status. RESULTS: Dual immunohistochemistry allowed for the identification of LI in 33 cases (26%), compared to only 2% on H&E stained sections. Melanomas with LI showed greater thickness, higher mitotic rate and more frequent ulceration. Eleven of 33 cases with LI (33%) and 10 of 92 cases without LI (11%) were associated with a positive SLN (P = .006). More patients without LI were disease-free at last follow-up (80%) than patients with LI (50%; P = .002); LI was significantly associated with decreased progression-free survival. CONCLUSION: The detection of LI is improved by dual immunohistochemistry and predicts SLN metastasis. The presence of LI may impact therapeutic planning in melanoma, such as the decision to perform a SLN biopsy.

Differential UBE2C and HOXA1 expression in melanocytic nevi and melanoma.

BACKGROUND: Recent molecular advances suggest that Spitz nevi and other spitzoid neoplasms are biologically distinct from melanoma and conventional nevi. The ubiquitin ligase UBE2C and the homeobox transcription factor HOXA1 are candidate oncogenes in melanoma. METHODS: Using RNA expression analysis and immunohistochemistry, we evaluated these biomarkers in Spitz nevi (n = 20), melanoma (n = 20), and by immunohistochemistry in conventional nevi (n = 20). RESULTS: RNA analysis with branched DNA multiplex assay identified upregulation of UBE2C in melanomas vs Spitz nevi (P = .003), whereas HOXA1 was downregulated in melanoma (P < .0001). Immunohistochemical analysis confirmed increased nuclear expression of UBE2C in melanoma (mean = 18% of cells; range 3%-44%) when compared with Spitz nevi (mean = 9%; range 2%-28%; P = .001) and conventional nevi (mean = 1.5%; range 0-9%; P < .0001). Strong UBE2C staining was identified in cells undergoing mitosis. UBE2C RNA and protein detection correlated with mitotic rate (P < .0001). On the other hand, HOXA1 nuclear staining was low in melanoma (mean = 69%; range 5%-100%) when compared with Spitz nevi (mean = 94%; range 66%-100%; P = .0024) and conventional nevi (mean = 94%; range 83%-99%; P = .009). CONCLUSIONS: UBE2C and HOXA1 RNA and protein are differentially expressed in conventional and Spitz nevi and melanoma.

The tetraspanin CD63 is required for efficient IgE-mediated mast cell degranulation and anaphylaxis.

Mast cell (MC) activation through the high-affinity IgE receptor FcεRI leads to the release of mediators involved in immediate-type allergic reactions. Although Abs against the tetraspanins CD63 and CD81 inhibit FcεRI-induced MC degranulation, the intrinsic role of these molecules in FcεRI-induced MC activation is unknown. In MCs, CD63 is expressed at the cell surface and in lysosomes (particularly secretory lysosomes that contain allergic mediators). In this study, we investigated the role of CD63 in MC using a CD63 knockout mouse model. CD63-deficiency did not affect in vivo MC numbers and tissue distribution. Bone marrow-derived MC developed normally in the absence of CD63 protein. However, CD63-deficient bone marrow-derived MC showed a significant decrease in FcεRI-mediated degranulation, but not PMA/ionomycin-induced degranulation, as shown by ß-hexosaminidase release assays. The secretion of TNF-α, which is both released from granules and synthesized de novo upon MC activation, was also decreased. IL-6 secretion and production of the lipid mediator leukotriene C4 were unaffected. There were no ultrastructural differences in granule content and morphology, late endosomal/lysosomal marker expression, FcεRI-induced global tyrosine phosphorylation, and Akt phosphorylation. Finally, local reconstitution in genetically MC-deficient Kit(w/w-v) mice was unaffected by the absence of CD63. However, the sites reconstituted with CD63-deficient MC developed significantly attenuated cutaneous anaphylactic reactions. These findings demonstrate that the absence of CD63 results in a significant decrease of MC degranulation, which translates into a reduction of acute allergic reactions in vivo, thus identifying CD63 as an important component of allergic inflammation.

Ras, Raf, and MAP kinase in melanoma.

A growing understanding of the biology and molecular mechanisms of melanoma has led to the identification of a number of driver mutations for this aggressive tumor. The most common mutations affect signaling of the Ras/Raf/MAPK (mitogen-activated protein kinase) pathway. This review will focus on mutations in genes encoding proteins that play a role in the MAPK pathway and that have been implicated in melanoma biology, such as BRAF, NRAS, and MEK (MAPK kinase), and detail the current understanding of their role in melanoma progression from a molecular biology perspective. Furthermore, this review will also consider some additional mutations in genes such as KIT, GNAQ, and GNA11, which can be seen in certain subtypes of melanoma and whose gene products interact with the MAPK pathway. In addition, the association of these molecular changes with clinical and classical histopathologic characteristics of melanoma will be outlined and their role in diagnosis of melanocytic lesions discussed. Finally, a basic overview of the current targeted therapy landscape, as far as relevant to the pathologist, will be provided.

Aleukemic cutaneous myeloid sarcoma.

BACKGROUND: Aleukemic cutaneous myeloid sarcoma (CMS) represents an important yet rare entity denoting the presence of a cutaneous myeloid leukemic infiltrate without concurrent peripheral blood or bone marrow disease. The clinicopathologic diagnosis remains elusive due to isolated skin findings and variable immunostaining. Cytogenetic and molecular findings have infrequently been reported. METHODS: Twenty-five patients with CMS were identified in the Massachusetts General Hospital pathology database between 2004 and 2012. Patients were excluded if concurrent blood or marrow acute myeloid leukemia (AML), myelodysplastic syndrome or lymphoproliferative disorder were diagnosed. RESULTS: Three patients were identified: a neonate with recurrent CMS and marrow disease that never met diagnostic criteria for AML and two patients relapsing as CMS without concurrent blood or marrow disease following chemotherapy-induced complete remission. Histology showed atypical mononuclear cell interstitial dermal infiltrates. All cases were CD68+, lysozyme+ and CD117-; one of two were CD34+; two of three were myeloperoxidase negative. 11q23 rearrangement, t(1;14), NPM1 (nucleophosmin I), FLT3-ITD (Fms-like tyrosine kinase 3-internal tandem duplication), and novel FLT3-D835 mutations were identified. CONCLUSION: An isolated atypical cutaneous infiltrate may represent aleukemic CMS and should prompt a search for other extramedullary sites of involvement. Immunohistochemistry, molecular and cytogenetic studies can help differentiate aleukemic CMS from benign and malignant, monocytic and histiocytic mimickers, and may potentially indicate therapy and prognosis.

Bis-N-heterocyclic carbene palladium(IV) tetrachloride complexes: synthesis, reactivity, and mechanisms of direct chlorinations and oxidations of organic substrates.

This Article describes the preparation and isolation of novel octahedral CH(2)-bridged bis-(N-heterocyclic carbene)palladium(IV) tetrachlorides of the general formula LPd(IV)Cl(4) [L = (NHC)CH(2)(NHC)] from LPd(II)Cl(2) and Cl(2). In intermolecular, nonchelation-controlled transformations LPd(IV)Cl(4) reacted with alkenes and alkynes to 1,2-dichlorination adducts. Aromatic, benzylic, and aliphatic C-H bonds were converted into C-Cl bonds. Detailed mechanistic investigations in the dichlorinations of alkenes were conducted on the 18VE Pd(IV) complex. Positive solvent effects as well as kinetic measurements probing the impact of cyclohexene and chloride concentrations on the rate of alkene chlorination support a Pd(IV)-Cl ionization in the first step. Product stereochemistry and product distributions from various alkenes also support Cl(+)-transfer from the pentacoordinated Pd(IV)-intermediate LPd(IV)Cl(3)(+) to olefins. 1-Hexene/3-hexene competition experiments rule out both the formation of π-complexes along the reaction coordinate as well as in situ generated Cl(2) from a reductive elimination process. Instead, a ligand-mediated direct Cl(+)-transfer from LPd(IV)Cl(3)(+) to the π-system is likely to occur. Similarly, C-H bond chlorinations proceed via an electrophilic process with in situ formed LPd(IV)Cl(3)(+). The presence of a large excess of added Cl(-) slows cyclohexene chlorination while the presence of stoichiometric amounts of chloride accelerates both Pd(IV)-Cl ionization and Cl(+)-transfer from LPd(IV)Cl(3)(+). (1)H NMR titrations, T1 relaxation time measurements, binding isotherms, and Job plot analysis point to the formation of a trifurcated Cl(-)···H-C bond in the NHC-ligand periphery as a supramolecular cause for the accelerated chemical events involving the metal center.

Anti-CD63 antibodies suppress IgE-dependent allergic reactions in vitro and in vivo.

High-affinity IgE receptor (FcepsilonRI) cross-linking on mast cells (MCs) induces secretion of preformed allergy mediators (degranulation) and synthesis of lipid mediators and cytokines. Degranulation produces many symptoms of immediate-type allergic reactions and is modulated by adhesion to surfaces coated with specific extracellular matrix (ECM) proteins. The signals involved in this modulation are mostly unknown and their contribution to allergic reactions in vivo is unclear. Here we report the generation of monoclonal antibodies that potently suppress FcepsilonRI-induced degranulation, but not leukotriene synthesis. We identified the antibody target as the tetraspanin CD63. Tetraspanins are membrane molecules that form multimolecular complexes with a broad array of molecules including ECM protein-binding beta integrins. We found that anti-CD63 inhibits MC adhesion to fibronectin and vitronectin. Furthermore, anti-CD63 inhibits FcepsilonRI-mediated degranulation in cells adherent to those ECM proteins but not in nonadherent cells. Thus the inhibition of degranulation by anti-CD63 correlates with its effect on adhesion. In support of a mechanistic linkage between the two types of inhibition, anti-CD63 had no effect on FcepsilonRI-induced global tyrosine phosphorylation and calcium mobilization but impaired the Gab2-PI3K pathway that is known to be essential for both degranulation and adhesion. Finally, we showed that these antibodies inhibited FcepsilonRI-mediated allergic reactions in vivo. These properties raise the possibility that anti-CD63 could be used as therapeutic agents in MC-dependent diseases.