Search Results (261)

Background: Specimens with low cell counts may fail to yield sufficient analyzable metaphases or are rejected for chromosomal analysis. Buffy coat enrichment (BCE) concentrates nucleated cells prior to culture; however, its impact on routine cancer cytogenetics has not been systematically evaluated. Methods: We first validated BCE in hypocellular specimens (<5 K/µL) and then conducted a prospective quality improvement study from November 2024 to October 2025, encompassing 12,088 specimens. A phased intervention strategy was implemented by performing BCE on specimens with cell counts of 2.0–4.9 K/µL (designated as phase I); followed by expanding BCE to specimens with cell counts of 1.0–4.9 K/µL (phase II). Outcomes were assessed by the rate of successful karyotypes, defined as ≥10 analyzable metaphases. Results: In the validation cohort (cell counts < 5 K/µL), BCE improved the success rate across all cell count strata. In the prospective study cohort, implementation of BCE increased the overall success rate from 78% at baseline to 83% in phase I, and further increased to 90% in phase II. Conclusions: BCE significantly improves the success rate of chromosomal analysis by increasing the yield of metaphases in hypocellular specimens. This simple and scalable intervention reduces specimen rejection and enhances diagnostic yield in routine cancer cytogenetics. Full article

Background/Objectives: T-cell lymphomas are relatively common in veterinary species, yet current diagnostic tools such as PCR-based clonality assays often lack sensitivity and specificity. In humans, we recently developed two related tissue-based diagnostic approaches based on the differential detection of the mutually exclusively expressed TCRbeta1 and 2 (TCRβ1 and 2) constant region proteins, or the corresponding TRBC1 and TRBC2 transcripts. Analogous to the detection of kappa/lambda light chains for the diagnosis of B-cell/plasma cell neoplasms in human clinical practice, our TCRβ1/2 diagnostic assay has the potential to transform veterinary diagnostic workflows. Methods: We identified and confirmed the sequences of the relevant TRBC1 and TRBC2 sequences in both cats and dogs, focusing on the 3′ untranslated region (UTR), where there is the least sequence homology between TRBC1 and TRBC2. To allow us to design appropriate probe sequences, we confirmed a lack of 3′UTR in either species, and we observed limited 3′ untranslated region UTR sequence polymorphism in the cat but not in the dog 3′UTR. We designed BaseScope™ RNA in situ hybridization probes targeting the 3′ UTR to distinguish between TRBC1 and TRBC2 transcripts in formalin-fixed paraffin-embedded tissues. Results: In normal tissues, we found the TRBC2:TRBC1 expression ratio to be similar to the 1.2:1 ratio in humans, between 1:1 and 3:1, skewing towards TRBC2, in both dogs and cats. These findings were corroborated using quantitative reverse transcription PCR. Applying our in situ hybridization probes to cases of T-cell lymphoma in dogs and cats, we demonstrated that an assay for differential expression of TRBC1 and TRBC2 in T-cell populations could identify clonal T-cell populations, as in human diagnostics. If further studies corroborate this proof-of-concept study, TRBC1/2 detection could obviate the need for slow, complex and expensive multiplexed PCR-based (PCR for antigen receptor rearrangements (PARR)) clonality assays. Conclusions: This study provides proof-of-concept data for a novel diagnostic approach that could simplify and substantially improve the accuracy of lymphoma diagnostics in veterinary medicine, by detecting TRBC1/2 transcripts. Full article

In idiopathic azoospermia caused by non-obstructive infertility with AZFc deletion, the testicle usually contains an increased number of mast cells (MCs)—which are responsible for collagen synthesis in the testes—as well as Leydig cell hyperplasia. However, the relationship between MCs and telocytes in this pathology remains unexplored. The aim of this study was to examine ultrastructural changes in the interstitial tissue microenvironment of the convoluted seminiferous tubules in the testis, using clinical specimens from men with genetically determined non-obstructive infertility with AZFc deletion. Histological, immunohistochemical, and electron microscopic (EM) studies were performed on surgical materials from 14 patients with AZFc deletion. The IHC study was performed using a panel of antibodies: tryptase, chymase, carboxypeptidase A3, and αSMA. The EM study was performed on ultrathin sections with a thickness of 100–120 nm. MCs were found to be in a functionally active state and characterized by a variety of secretory activities. For the first time, telocytes and their colocalization with MCs and Leydig cells were visualized. It is possibly the telocytes—interacting with MCs—that synchronize the functional activity of the entire MC population of the testis. The interaction of MCs with telocytes, as well as individual secretory granules associated with loci of tropocollagen and collagen microfibril accumulation, leads to the accumulation of collagen fibrils in the interstitium, as observed in idiopathic infertility with AZFc deletion. Even with a small number of MCs in the interstitium of the convoluted seminiferous tubules in the testis, the telocytes are able to synchronize MCs’ activation and secretory activity, supporting the development of a profibrotic phenotype of the tissue microenvironment. The obtained results advance our understanding of idiopathic infertility with AZFc deletion by delineating the ultrastructural landscape of the testicular interstitium and establishing telocytes as key regulators of cellular crosstalk. Telocytes use complex mechanisms for the spatial integration of MCs and fibroblasts in the profibrotic phenotype formation of the convoluted seminiferous tubule tissue microenvironment. Potentially, telocytes can directly be involved in synchronizing such processes by activating the biogenesis and secretion of collagen monomers by fibroblasts; the MC secretome directly affects the polymerization of collagen monomers and dimers into microfibrils in the extracellular matrix, stimulating excessive collagen fiber formation and the development of fibrotic changes. Full article

Background: Acute myeloid leukemia (AML) with CBFB::MYH11 fusion and myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) are genetically defined and typically mutually exclusive entities. Case Presentation: We report a unique case of de novo AML harboring two clonal, transcriptionally active class-defining fusions: CBFB::MYH11 and GOLGA4::PDGFRB. A 61-year-old woman presented with leukocytosis with neutrophilia, eosinophilia, and monocytosis; circulating blasts; and a markedly hypercellular marrow. Cytogenetic analysis revealed inv(16)(p13.1q22) and t(3;5)(p21;q32) in all 20 metaphases, and RNA sequencing confirmed expression of both CBFB::MYH11 and GOLGA4::PDGFRB fusions. In addition, an oncogenic WT1 frameshift variant was identified. Hematopathologic findings were largely consistent with AML with CBFB::MYH11 fusion but exhibited features reminiscent of PDGFRB-rearranged MLN-TK. The patient achieved complete remission following the standard 7 + 3 induction chemotherapy regimen for AML with gemtuzumab ozogamicin. Conclusions: This case illustrates the diagnostic challenges posed by concomitant class-defining alterations in hematologic neoplasms and underscores the importance of integrated genomic assessment. Full article

Background and Objectives: Diagnostics for hematologic diseases rely on integrated assessment of clinical manifestation, morphology, flow cytometry, and molecular testing. Current classification systems, including the WHO HAEM5 and the International Consensus Classification, highlight the central role of genomics in defining disease entities and risk. Simultaneously, laboratories face growing case complexity and staffing challenges. Automation, collaborative robots (cobots), digital morphology platforms, and artificial intelligence (AI) have begun to address these issues. Here we examine the application of these technologies in hematopathology and molecular diagnostics and consider their translational potential to improve diagnostic accuracy and, ultimately, patient care. Methods: A review of peer-reviewed literature and technical reports published through December 2025 was performed, focusing on digital morphology platforms, AI for peripheral blood and marrow interpretation, AI-enabled flow cytometry, automated and robotic deployments in clinical laboratories, and machine learning applications in molecular hematopathology. Results: Digital morphology analyzers show strong concordance with manual microscopy and now serve as efficient platforms for AI-assisted differentials, cell classification, and fibrosis quantification. Deep learning applied to multiparameter flow cytometry achieves performance comparable to expert review in distinguishing mature B-cell neoplasms and acute leukemias. Automated solutions, cobot systems and robotic-arm-based slide-scanning clusters have demonstrated substantial gains in throughput and pre-analytic consistency. AI models in molecular hematopathology increasingly assist with variant interpretation, genetic risk stratification, and linking morphologic and genomic findings. Conclusions: AI is beginning to change how hematopathology and molecular diagnostics are practiced. Successful translation will depend on disease-specific validation, the development of multi-modal models aligned with ICC and WHO frameworks, and laboratory governance that maintains expert oversight. Full article

Background: Artificial intelligence (AI) shows promising results in lymphoma detection, prediction, and classification. However, translating these findings into practice requires a rigorous assessment of potential biases, clinical utility, and further validation of research models. Objective: The goal of this study was to summarize existing studies on artificial intelligence models for the histopathological detection of lymphoma. Design: This study adhered to the PRISMA Extension for Scoping Reviews (PRISMA-ScR) guidelines. A systematic search was conducted across three major databases (Scopus, PubMed, Web of Science) for English-language articles and reviews published between 2016 and 2025. Seven precise search queries were applied to identify relevant publications, accounting for variations in study modality, algorithmic architectures, and disease-specific terminology. Results: The search identified 612 records, of which 36 articles met the inclusion criteria. These studies presented 36 AI models, comprising 30 diagnostic and six prognostic applications, with Convolutional Neural Networks (CNNs) being the predominant architecture. Regarding data sources, 83% (30/36) of datasets utilized Hematoxylin and Eosin (H&E)-stained images, while the remainder relied on diverse modalities, including IHC-stained slides, bone marrow smears, and other tissue preparations. Studies predominantly utilized retrospective, private cohorts with sample sizes typically ranging from 50 to 400 patients; only a minority leveraged open-access repositories (e.g., Kaggle, TCGA). The primary application was slide-level multi-class classification, distinguishing between specific lymphoma subtypes and non-neoplastic controls. Beyond diagnosis, a subset of studies explored advanced prognostic tasks, such as predicting chemotherapy response and disease progression (e.g., in CLL), as well as automated biomarker quantification (c-MYC, BCL2, PD-L1). Reported diagnostic performance was generally high, with accuracy ranging from 60% to 100% (clustering around 90%) and AUC values spanning 0.70 to 0.99 (predominantly >0.90). Conclusions: While AI models demonstrate high diagnostic accuracy, their translation into practice is limited by unstandardized protocols, morphological complexity, and the “black box” nature of algorithms. Critical issues regarding data provenance, image noise, and lack of representativeness raise risks of systematic bias, hence the need for rigorous validation in diverse clinical environments. Full article

The World Health Organization (WHO) and International Consensus Classification (ICC) systems have classified EBV-positive NK/T-cell neoplasms in adults and EBV-positive T/NK-cell lymphoid lymphoproliferative disorders (LPD) in children. Recent molecular profiling techniques have revealed the pathogenesis of these disorders, showing interactions among EBV-encoded proteins, host immune responses, and genetic alterations. Extranodal NK/T-cell lymphoma (ENKTL) shows molecular diversity, with various subtypes (TSIM, MB, and HEA) identified through a multiomics approach. Aggressive NK-cell leukemia (ANKL) has mutations in JAK/STAT, epigenetic regulators, and TP53 pathways. EBV-positive nodal T- and NK-cell lymphoma (ENTNKL) is a new entity, distinguished by primary nodal presentation and a unique molecular profile. Severe mosquito bite allergy (SMBA), hydroa vacciniforme lymphoproliferative disorder (HVLPD), and systemic chronic active EBV disease (CAEBV) are rare childhood EBV-driven LPDs defined by clinico-pathologic criteria, with largely unexplored genomic landscapes. Studies of CAEBV samples have found ENKTL-like driver mutations, including DDX3X and KMT2D, in EBV-infected NK/T cells, while KMT2D and chromatin modifier mutations were common in HVLPD. Comprehensive molecular sequencing of SMBA and Systemic EBV-positive T-cell lymphoma of childhood remains lacking. These findings suggest all EBV⁺ NK/T-cell LPDs exist on a biological continuum of viral oncogenesis. The integration of clinical, pathological, and molecular information aims to create a more accurate classification system, enabling better risk evaluation and tailored treatment strategies for patients with these complex disorders. Full article

Background: Optical genome mapping (OGM) detects genome-wide structural variants (SVs), including balanced rearrangements and complex copy-number alterations beyond standard-of-care cytogenomic assays. In chronic lymphocytic leukemia (CLL), cytogenetic and genomic risk stratification is traditionally based on fluorescence in situ hybridization (FISH), karyotyping, targeted next-generation sequencing (NGS), and immunogenetic assessment of immunoglobulin heavy chain variable region (IGHV) somatic hypermutation status, each of which interrogates only a limited aspect of disease biology. Methods: We retrospectively evaluated fifty patients with CLL using OGM and integrated these findings with cytogenomics, targeted NGS, IGHV mutational status, and clinical time-to-first-treatment (TTFT) data. Structural variants were detected using OGM and pathogenic NGS variants were derived from a clinical heme malignancy panel. Clinical outcomes were extracted from the electronic medical record. Results: OGM identified reportable structural variants in 82% (41/50) of cases. The most frequent abnormality was del(13q), observed in 29/50 (58%) and comprising 73% (29/40) of all OGM-detected deletions with pathologic significance. Among these, 12/29 (42%) represented large RB1-spanning deletions, while 17/29 (58%) were focal deletions restricted to the miR15a/miR16-1 minimal region, mapping to the non-coding host gene DLEU2. Co-occurrence of adverse lesions, including deletion 11q/ATM, BIRC3 loss, trisomy 12, and deletion 17p/TP53, were recurrent and strongly associated with shorter TTFT. OGM also uncovered multiple cryptic rearrangements involving chromosomal loci that are not represented in the canonical CLL FISH probe panel, including IGL::CCND1, IGH::BCL2, IGH::BCL11A, IGH::BCL3, and multi-chromosomal copy-number complexity. IGHV data were available in 37/50 (74%) of patients; IGHV-unmutated status frequently co-segregated with OGM-defined high-risk profiles (del(11q), del(17p), trisomy 12 with secondary hits, and complex genomes whereas mutated IGHV predominated in OGM-negative or structurally simple del(13q) cases and aligned with indolent TTFT. Integration of OGM with NGS further improved genomic risk classification, particularly in cases with discordant or inconclusive routine testing. Conclusions: OGM provides a comprehensive, genome-wide view of structural variation in CLL, resolving deletion architecture, identifying cryptic translocations, and defining complex multi-hit genomic profiles that tracked closely with clinical behavior. Combining OGM and NGS analysis refined risk stratification beyond standard FISH panels and supports more precise, individualized management strategies in CLL. Prospective studies are warranted to evaluate the clinical utility of OGM-guided genomic profiling in contemporary treatment paradigms. Full article

Background: KMT2A partial tandem duplication (PTD) occurs in approximately 5–10% of acute myeloid leukemia (AML) cases and is associated with poor prognosis. While its cytogenetic and molecular features are well described, the immunophenotypic characteristics of AML with KMT2A-PTD remain incompletely defined. Methods: We identified 47 cases of AML with KMT2A-PTD by optical genome mapping. All cases underwent flow cytometric immunophenotypic analysis and next-generation sequencing using an 81-gene panel. Results: The cohort included 32 men and 15 women with a median age of 67 years (range, 19–87). Thirty-eight cases were de novo AML, and nine were secondary to myelodysplastic syndrome and/or myeloproliferative neoplasm. Most cases (93%) demonstrated a normal or non-complex karyotype. The most frequent mutations involved FLT3-ITD (47%), DNMT3A (43%), and RUNX1 (23%). Thirty-one cases (66%) were granulocytic, while 16 (34%) showed granulocytic and/or monocytic differentiation. Blasts uniformly expressed HLA-DR and frequently expressed CD117 (91%) and CD34 (79%). Increased expression of CD123 (74%) and CD117 (43%) and decreased expression of HLA-DR (74%) and CD38 (69%) were common. Aberrant CD25 expression was observed in 51% of cases. Increased CD123 and aberrant CD25 expression were significantly associated with FLT3-ITD mutations (both p < 0.0001) but not with other recurrent mutations. There was no correlation between FLT3-ITD mutation and expression levels of CD117, CD38 or HLA-DR (all p > 0.05). Conclusions: AML with KMT2A-PTD shows distinctive immunophenotypic features with increased CD123 and aberrant CD25 expression, both associated with FLT3-ITD. These markers may have diagnostic and therapeutic relevance in this AML subtype. Full article

A key function of naturally occurring antibodies is to control pathologically altered cells, such as those with aberrant glycosylation. Age-related diminution in the pool of B cells producing these immunoglobulins is linked to impaired anti-tumor immunity. In this study, the levels of antibodies against tumor-associated carbohydrate antigens (TACAs)—common in gastric cancer (GC) and other malignancies—were analyzed in 235 treatment-naïve GC patients (stages I–IV) and 76 healthy donors using a printed glycan array (PGA). We found that anti-glycan IgM levels, but not IgG, reduced with age in both patients and donors. Crucially, IgM levels against most glycans were significantly lower in the GC cohort compared with healthy donors, a trend that remained after age adjustment. Furthermore, an immunohistochemical analysis revealed that human anti-GalNAcα (Tn) antibodies—a well-characterized TACA in gastrointestinal cancers—bound to tumor cells and exhibited perinuclear and membrane staining in non-tumor surface cells within the same organ. These data support the hypothesis that gastric cancer patients have reduced levels of anti-glycan IgMs, which are responsible for the early recognition of transformed cells. This specific immunodeficiency may contribute to a permissive environment for tumor development. Full article

Background: Evidence on non-restrictive MIND pattern interventions in Alzheimer’s (ALZ) disease remains limited. Methods: In an observational case–control study, 60 participants (ALZ, n = 30; cognitively healthy controls, n = 30) completed baseline (T0) and follow-up (T1) after structured MIND counseling. Adherence was assessed via the MEDAS questionnaire. Stool samples (16S rRNA profiling) were taken and anthropometry and cognitive/functional measures were recorded at T0/T1. Results: In the ALZ group, MEDAS improved as adherence to the Mediterranean diet increased (increasing the use of vegetables ≥ 2/day, p < 0.01; and lowering butter adoption ≤ 1/day, p = 0.02), with a shift from low to moderate/high adherence; in controls, baseline Mediterranean diet adherence was already high, and changes in MEDAS categories were modest (low adherence from 13.8% to 3.6%, high adherence from 37.9% to 50.0%), with no statistically significant overall change (p = 0.39). Regarding gut microbiota (GM), in the ALZ group, alpha diversity increased significantly and Bray–Curtis PCoA separated T0 from T1. Species-level analysis showed increases in SCFA-linked taxa (e.g., Anaerobutyricum hallii, Blautia luti, Eubacterium coprostanoligenes) and reductions in dysbiosis/mucin-degrading taxa (e.g., Mediterraneibacter torques, M. gnavus, Agathobacter rectalis). Between-group Δ(T1 − T0) comparisons at the genus level indicated larger positive shifts in ALZ for Anaerobutyricum, Oscillibacter, Faecalicatena, Romboutsia, Mediterraneibacter, and Blautia, and more negative Δ for Gemmiger, Subdoligranulum, Bifidobacterium, Clostridium, and Collinsella. sPLS-DA showed partial separation (first two components ≈ 9% variance). Conclusions: A structured, non-restrictive MIND intervention was feasible, improved dietary adherence, and accompanied higher diversity and compositional remodeling of the GM in ALZ’s disease. Larger randomized mechanistic studies are warranted. Full article

Endometritis features an inflammatory milieu in the endometrium, accompanied by the recruitment of immunocompetent cells, including mast cells (MCs). The mechanisms underlying MC involvement in chronic endometritis (CE) and fibrous niche formation remain poorly understood, particularly regarding spatial intercellular interactions in situ. In this study, we used multiplex immunohistochemistry and quantitative immunofluorescence analysis to map the spatial phenotype of MC distribution. Standard histochemical techniques, monoplex and multiplex immunohistochemical staining technologies, light-field microscopy, epifluorescence, and confocal microscopy with multispectral imaging, combined with quantitative immunofluorescence analysis with AI application, were used to identify the spatial phenotyping of quantitative and qualitative features of the endometrial MC population in CE. The increased intensity of endometrial inflammation was accompanied by a rise in the profile of MC content in the endometrium; this accounted for a 0.014% increase in the control and 0.067%, 0.113%, and 0.206% increases in mild, moderate, and severe CE, respectively. We are the first to map the number of MCs that demonstrated loci of accumulations in the endometrium coinciding with foci of fibrous changes. The number of these foci correlated with the severity of chronic endometritis and the development of clinical signs. The frequency of juxtacrine and paracrine MC colocalization with other immunocompetent cells increased with increased CE activity and fibrotic changes: For CD8⁺ lymphocytes, colocalization increased from 4.6% in the control to 11.6%, 18.5%, and 28.0% in mild, moderate, and severe CE, respectively. For monocytes, colocalization increased from 5.6% in the control to 18.7%, 26.8%, and 28.8% in mild, moderate, and severe CE, respectively. For type 1 macrophages, colocalization increased from 5.6% in the control to 13.5%, 17.4%, and 24.6% in mild, moderate, and severe CE, respectively. For type 2 macrophages, colocalization increased from 3.4% in the control to 9.6%, 9.1%, and 21.5% in mild, moderate, and severe CE, respectively. Spatial patterns of juxtacrine and paracrine MC interactions with other immune cells may provide diagnostic algorithms for chronic endometritis, enabling targeted therapy and preventing fibrotic changes. Full article

Gene fusions involving NUTM1 have been increasingly recognized in hematologic malignancies, though their role in acute myeloid leukemia (AML) remains poorly understood. We retrospectively analyzed 565 unique AML patients with reported fusion results who underwent comprehensive next-generation sequencing (NGS) between March 2022 and December 2023. Among them, three novel in-frame NUTM1 fusion transcripts, LARP1::NUTM1, ARHGAP15::NUTM1, and GABPB1::NUTM1, were identified in three relapsed or refractory AML cases, all with monocytic differentiation. Ancillary studies included flow cytometry, cytogenetics, FISH, and comprehensive mutational profiling. All three patients eventually relapsed and succumbed to their disease, despite initial responses in one case. Each case also harbored co-occurring mutations associated with adverse prognosis, such as BCOR, ASXL1, and RUNX1. These findings suggest NUTM1 fusions in AML could represent a distinct molecular subset with potentially poor prognosis, warranting further functional and clinical investigation to clarify their biological and therapeutic significance. Full article

Background and Clinical Significance: Mastocytosis and mast cell activation syndrome (MCAS) include conditions in which patients manifest signs, symptoms, and laboratory findings consistent with mast cell activation and can only be diagnosed in the presence of specific criteria. Mutations of ZRSR2, a gene involved in RNA splicing, are not closely associated with mast cell disorders, but rather with myelodysplastic syndromes development. Case Presentation: We report a case of a 37-year-old man who was referred to our institution for anaphylaxis after a bee sting and elevated serum tryptase levels (17.8 ng/mL in the first sample and 19.2 ng/mL in the second sample). Complete blood count was unremarkable. Bone marrow biopsy showed signs of dysplasia and some CD25+ mast cells. ASO-qPCR and targeted myeloid NGS analysis did not detect the KIT p.D816V mutation, but rather showed the presence of a pathogenetic variant of the ZRSR2 gene (p.S447_R448del) with a variant allele frequency of 7.4%. Mastocytosis could not be diagnosed based on the established diagnostic criteria. The patient’s symptoms were not recurrent and tryptase release was not event-related; therefore, a diagnosis of MCAS could not be made either. Taken together, these findings led to the diagnosis of clonal hematopoiesis of indeterminate potential (CHIP). A watch and wait strategy consisting of clinical evaluations, blood tests, and cardiovascular risk assessment was initiated. Conclusions: This case report highlights the importance of combining clinical and laboratory findings, hematopathology, and molecular analyses to establish the most probable diagnosis in challenging cases. It also underscores the possible relevance of identifying predisposing conditions, such as CHIP, in order to guide counseling and follow-up strategy. Full article

Cutaneous melanoma remains one of the most aggressive tumors, yet the role innate immunity plays in its progression remains poorly understood. Effector elements with high regulatory potential, capable of both promoting and inhibiting tumor growth—mast cells (MCs), are of particular interest. This includes quantitatively characterizing the interactions between tryptase-positive mast cells (MCs) with atypical Melanin—A⁺ cells and describing their spatial phenotype, in relation to the stage of cutaneous melanoma. A retrospective analysis was carried out on samples retrieved from 128 patients with cutaneous melanoma (AJCC 8th edition: IA–IIID). Histological analysis, histochemistry (toluidine blue, Giemsa), and diplex /multiplex IHC for tryptase and Melan-A were performed; as well as Fluorescence imaging, 3D reconstructions and quantitative mapping in QuPath v 0.6.0. Proximity was assessed by the nucleus-to-nucleus distance: <10 μm (contact), 10–20 μm (paracrine zone), >20 μm (out of interaction). The relative amount of MCs in the intratumoral zone was lower than in the intact dermis, with a simultaneous increase in their absolute density per mm² in the melanoma microenvironment, maximum in the peritumoral area and most pronounced at stage II. Three types of interactions were identified: (i) juxtaposition without secretion, (ii) degranulation of MCs directed to tumor cells, (iii) melanosecretion of Melanin—A⁺ cells directed towards MCs, followed by phagocytosis of melanocores. An inverse intratumoral connection between the number of MCs and the number of Melanin—A⁺ cells was noted; MCs with elongated forms, extensive contacts and polarized tryptase secretion, including granule localization near/at the nuclei of adjacent cells, were frequently observed. The obtained data indicate stage-region-dependent bidirectional cross-talk between melanin and MCs, forming tissue spatial signals, potentially useful as biomarkers and targets for personalized therapy. Full article