Peripheral Nerve Sheath Tumors in Patients With Neurofibromatosis Type 1: Morphological and Immunohistochemical Study.

BACKGROUND/AIM: The aim of the present investigation was to characterize the growth pattern and antigen profile of peripheral nerve sheath tumors (PNST) in a large series of tumors obtained from patients with Neurofibromatosis type 1 (NF1) focusing on morphological characteristics of diffuse plexiform neurofibroma (DPNF). MATERIALS AND METHODS: Tissue micro-array (TMA) analysis was applied to study 520 formalin-fixed, paraffin-embedded human PNST of 385 patients with confirmed NF1 diagnosis. PNST originated from all areas of the body and were classified as cutaneous neurofibroma (CNF, n=114), diffuse neurofibroma (DNF, n=109), DPNF (n=108), plexiform neurofibroma (PNF, n=110), and malignant peripheral nerve sheath tumor (MPNST, n=22). Histomorphology and antigen expression patterns of the tumors were determined [S100, epithelial membrane antigen (EMA), CD90, mast cell tryptase, and neurofilament]. RESULTS: Benign PNST showed significantly more S100-positive tumor cells than MPNST (p<0.001). EMA expression was most pronounced in perineurium of DPNF. The number of mast cells in CNF, DNF and DPNF was significantly higher compared to PNF and MPNST (p<0.001 for both comparisons, Mann-Whitney U-test). CONCLUSION: DPNF show some distinct cellular characteristics. A high number of EMA positive cells possibly indicates the dissemination of perineural cells to the surrounding tissue. Concerning mast cell density, DPNF resemble DNF and CNS rather than PNF. Close contact of tumor cells in DPNF, DNF and CNF with the immune system is a prerequisite for permanent immunological reactions in contrast to PNF in which tumor cells are partitioned from the immune system by the perineurium and blood-nerve barrier of blood vessels. It is assumed that these morphological distinctions may reflect in part the biological differences between the entities. While PNF is a known precancerous stage in NF1 patients, DPNF are not rated as such. Furthermore, the morphologic differences between benign nerve sheath tumors may be important for the efficacy of drugs to access tumor cells.

Mimics of Allergy and Angioedema: Scombroid, Mast Cell Activation Disorders, and Hereditary Alpha Tryptasemia.

Scombroid poisoning, systemic mastocytosis, and hereditary alpha tryptasemia all present with episodes that resemble allergic reactions. Knowledge regarding systemic mastocytosis and hereditary alpha tryptasemia is quickly evolving. Epidemiology, pathophysiology, and strategies to identify and diagnose are discussed. Evidence-based management in the emergency setting and beyond is also explored and summarized. Key differences are described between these events and allergic reactions.

Tumor Cell Microenvironment and Microvessel Density Analysis in MALT Type Lymphoma.

BACKGROUND/AIM: MALT type lymphoma belongs to marginal zone lymphoma (MZL). MALT lymphomas' inflammatory microenvironment contributes to the pathogenesis of this cancer. In this study, we analyzed and quantified the tumor inflammatory microenvironment in MALT lymphoma samples and in healthy controls, and the microvessel content by immunohistochemistry and morphometric estimation. PATIENTS AND METHODS: Biopsy specimens from MALT type lymphoma patients and from non-metastatic axillary lymph nodes (CTRL) were analyzed by immunochemistry in order to quantify CD3, CD4, CD8, CD68, CD163, tryptase, CD34, and Ki67 positive cells. RESULTS: A substantial increase in the number of cells that were positive for the above markers and microvascular density (MVD) were observed in the MALT group. We also found a positive correlation between microvessels and CD8+ cells and between CD8+ cells and M2 type macrophages, while tryptase+ mast cells correlated with CD4+ cells. The mitotic proliferation index Ki67 was higher in MALT samples. CONCLUSION: The interactions between inflammatory cells in the tumor microenvironment and their correlation with angiogenesis is a useful tool in the development of new immunotherapy strategies.

[Tryptase: A practical guide for the physician]. / Dosage de la tryptase : un guide d'utilisation pour le clinicien.

Tryptase is the most abundant endopeptidase released by mast cells degranulation, involved in many pro and anti-inflammatory processes. Normal serum tryptase range is 0-11.4 µg/L. Tryptase is a useful diagnostic tool for anaphylaxis, systemic mastocytosis (SM) and mast cell activation syndrome (MCAS), where specific threshold values must be used. SM diagnosis criteria include evidence of dense mast cell infiltrate either in the bone marrow or the affected organ (such as skin), presence of KIT D816V mutation and elevated serum tryptase level (>20 µg/L). In SM, tryptase level is correlated with the burden of mast cells in bone marrow. MCAS should be considered in case of severe and recurrent typical clinical signs of systemic mast cell activation involving at least two organs, associated with an increase in serum tryptase level of 20% + 2 µg/L from the individual's baseline. Anaphylaxis is the most severe among hypersensitivity reactions. A clonal mast cell disorder is a central question in anaphylaxis and appropriate explorations should be conducted in these patients. Triggers for anaphylactic reactions vary significantly in the general population and in patients with MS or MCAS. Finally, physicians must be aware of the many pathological and physiological situations that affect tryptase levels.

High Extratumoral Mast Cell Counts Are Associated with a Higher Risk of Adverse Prostate Cancer Outcomes.

BACKGROUND: Given our previous findings that low intratumoral and high extratumoral mast cell numbers are associated with higher risk of biochemical recurrence after radical prostatectomy, we now assessed this relationship with race and the development of metastases. METHODS: We stained for mast cell tryptase via IHC and fluorescent immunolabeling in 885 men across multiple tissue microarray sets designed to assess biomarkers in association with race and prostate cancer outcomes (median follow-up, 7.0 years). RESULTS: Intratumoral and extratumoral mast cell counts were significantly lower in tissues from African-American compared with European-American men, but not within strata of cancer grade. There was no association between mast cell counts and ERG positivity, PTEN loss, or TP53 missense mutation. Higher minimum extratumoral mast cells were associated with an increased risk of biochemical recurrence [comparing highest with lowest tertiles: HR, 1.61; 95% confidence interval (CI), 1.12-2.29; P trend = 0.01]; this pattern was similar among European-American and African-American men and by grade of disease. There was no significant association between minimum intratumoral mast cell count and biochemical recurrence, overall or within strata of race and grade. Finally, high minimum number of extratumoral mast cells was associated with prostate cancer metastases (comparing highest with lowest tertiles: HR, 2.12; 95% CI, 1.24-3.63; P trend = 0.01). CONCLUSIONS: High extratumoral mast cell numbers are associated with biochemical recurrence and the development of metastases after radical prostatectomy. IMPACT: Higher numbers of benign tissue mast cells are associated with a higher risk of adverse outcomes after radical prostatectomy, including metastatic prostate cancer.

Frequency of isolated cutaneous involvement in adult mastocytosis: a cohort study.

BACKGROUND: Mastocytosis is characterized by the accumulation/proliferation of abnormal mast cells. The frequency of isolated cutaneous involvement in adults with mastocytosis has not been fully determined. The main objective of our study was to assess the frequency of isolated cutaneous mastocytosis (CM) in adults with mastocytosis skin lesions. The second objective was to compare the clinical, histological, biological and imaging features in patients with isolated CM and patients with systemic mastocytosis (SM). METHODS: We included all patients with histology-proven mastocytosis skin lesions between January 2009 and December 2017. The mastocytosis diagnosis was made according to the international diagnostic criteria. All data were collected from a dedicated specific case report. RESULTS: Among 160 patients with mastocytosis skin lesions, 25 patients had isolated CM (15.6%), 105 had SM and 30 (18.7%) patients had undetermined mastocytosis. Skin KIT mutation (OR: 51.9, 95% CI: 3.9-678, P = 0.001) and high bone marrow tryptase (OR: 97.4, 95% CI: 10.3-915, P = 0.001) were strong predictors of SM. The prevalence of osteoporosis was higher in the SM population than in the isolated CM population. Moreover, a decrease in bone mineral density over a short period of follow-up (1-2 years) was associated with SM. There were no differences between the two groups regarding the frequency of mast cell activation symptoms, the presentation of skin lesions, the number of mast cells in the dermis and the level of serum tryptase. We propose considering the KIT mutation status and bone marrow tryptase levels to aid the diagnosis of isolated CM in adult mastocytosis patients. CONCLUSION: Only a small minority of adults with mastocytosis skin lesions has isolated cutaneous involvement. In 18.7% of mastocytosis cases, even complete workup does not allow for a precise classification of patients.

Distribution of mast cell subtypes in interstitial cystitis: implications for novel diagnostic and therapeutic strategies?

AIMS: To identify the presence and geographical distribution of mast cell (MC) subtypes: MCT (tryptase positive-chymase negative) and MCTC (tryptase positive-chymase positive) in bladder tissue. METHODS: Bladder tissue was obtained from patients with painful bladder syndrome/interstitial cystitis (n=14) and normal histology from University Hospital Southampton tissue bank. Sequential tissue slices were immunohistochemically stained for MC subtypes using anti-MC tryptase (for MCT and MCTC) and anti-MC chymase (for MCTC). Stained sections were photographed, and positively stained MCs were quantified using ImageJ. Data were analysed using descriptive statistics and individual paired t-tests. RESULTS: There was a significant difference in the density of MCs between each layer of the disease bladder, with the greatest accumulation within the detrusor (p<0.001). There was a significant increase in MCTC subtype in the lamina (p=0.009) in painful bladder syndrome/interstitial cystitis. CONCLUSIONS: Our results suggest that mastocytosis is present within all layers of disease bladder, especially the muscle layer. The varying increase in MC subtypes in the lamina and mucosa may explain the variability in painful bladder syndrome/interstitial cystitis symptoms. A high influx of MCTC in the mucosa of individuals who also had ulceration noted within their diagnostic notes may be of the Hunner's ulcer subclassification. These findings suggest a relationship between the pathogenesis of MC subtypes and the clinical presentation of painful bladder syndrome/interstitial cystitis. A cohort study would further elucidate the diagnostic and/or therapeutic potential of MCs in patients with painful bladder syndrome/interstitial cystitis.

Immunoreactivity to CYP24A1, but not vitamin D receptor, is increased in mast cells of keratinocyte skin cancers.

In mouse skin models, mast cells have been shown to express vitamin D receptor (VDR) that can mediate the immunosuppressive effects of ultraviolet B radiation and vitamin D3. However, VDR activation leads to the expression of CYP24A1, a hydroxylase that can inactivate vitamin D3 metabolites. To examine immunoreactivity to VDR and CYP24A1 in mast cells from normal human skin, keratinocyte skin cancers, and disorders of chronic inflammation. Frozen biopsies were collected from the non-lesional and lesional skin of patients with actinic keratosis (AK), Bowen's disease/squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and psoriasis. The expression of VDR and CYP24A1 in tryptase-positive mast cells was analysed using double-staining methods. Less than 0.5% of the mast cells were immunoreactive to VDR in both the non-lesional and lesional skin for all disease groups. In non-lesional skin, only 0.5-2.9% of the mast cells were immunopositive for CYP24A1, however, the percentage of mast cells containing CYP24A1 was significantly increased in lesional skin of AK, SCC, and BCC. In contrast to human skin, LAD2 mast cells cultured from a patient with mast cell sarcoma/leukaemia revealed that about 34% and 6.5% of the cells were immunopositive for VDR and CYP24A1, respectively. Whereas a very small proportion of mast cells in human skin express VDR and CYP24A1, the proportion of mast cells expressing CYP24A1 in keratinocyte skin cancers is increased; the mechanism underlying this is unclear.

Management of Mastocytosis in Pregnancy: A Review.

In this article, the authors present a case of pregnancy complicated by the need for management of indolent systemic mastocytosis. The diagnosis of mastocytosis is reviewed, as well as subtypes of mastocytosis and management options particularly in pregnancy. A table of pregnancy/lactaction categories for common medications used in mastocytosis is presented.

The relationship between breast cancer molecular subtypes and mast cell populations in tumor microenvironment.

Mast cells (MCs) are a part of the innate immune system. The MC functions toward cancer are partially based on the release of chymase and tryptase. However, the MC effect on breast cancer is controversial. The aim of our study was to investigate the presence of MCs in breast cancer tumors of different molecular subtypes and their relationships with other pathological prognostic factors. Tryptase- and chymase-positive mast cell densities were evaluated by immunohistochemistry in 108 primary invasive breast cancer tissue samples. Positive cells were counted within the tumor bed and at the invasive margin. For all analyzed MC subpopulations, we observed statistically significant differences between individual molecular subtypes of breast cancer. The significantly higher numbers of intratumoral chymase- and tryptase-positive mast cells were observed in luminal A and luminal B tumors compared to triple-negative and HER2+ non-luminal lesions. A denser MC infiltration was associated with lower tumor grade, higher ER and PR expression, lower proliferation rate as well as the lack of HER2 overexpression. The results obtained in our study indicate a possible association of chymase- and tryptase-positive MCs with more favorable cancer immunophenotype and with beneficial prognostic indicators in breast cancer.

T cells, mast cells and microvascular density in diffuse large B cell lymphoma.

Diffuse large B cell lymphoma (DLBCL) is recognized as the most common form of non-Hodgkin lymphoma (NHL), accounting for about 40 % of all cases of NHL. Among the cellular components of the tumor inflammatory infiltrate, T cells and mast cells have been demonstrated to be correlated with tumor angiogenesis. In this report, we have investigated CD3 and tryptase expression and their relationship with microvascular density (MVD) in DLBCL patients. Moreover, we determined the significance of CD3 expression in bulky and non-bulky disease. CD3 expression was significantly lower in bulky disease patients when compared to non-bulky ones. CD3 showed a positive correlation with tryptase and MVD, while multiple regression analysis efficaciously predicted MVD depending on CD3 and tryptase as predictors, supporting a complex interplay between these cells in sustaining tumor angiogenesis in DLBCL patients.

Epidermal Expression of Filaggrin/Profilaggrin Is Decreased in Atopic Dermatitis: Reverse Association With Mast Cell Tryptase and IL-6 but Not With Clinical Severity.

BACKGROUND: A decrease in filaggrin expression contributes to the pathogenesis of atopic dermatitis (AD) and can be modified by inflammatory factors. OBJECTIVES: The aim of this study was to determine the correlation of (pro)filaggrin (filaggrin and profilaggrin) expression with clinical severity in AD and with mast cell (MC) tryptase, chymase, and IL-6. METHODS: Punch biopsies were collected from 17 patients with moderate-to-severe AD and from 10 psoriatic patients. Atopic dermatitis severity was measured using different clinical parameters. (Pro)filaggrin, MC tryptase, chymase, and IL-6 were stained using immunohistochemical, enzymehistochemical, and sequential double-staining methods. RESULTS: (Pro)filaggrin expression was lower in the lesional than in the nonlesional granular layer in AD and was correlated negatively with itch severity but not with other severity parameters. (Pro)filaggrin expression was also decreased in the psoriatic lesions. In AD, (pro)filaggrin expression correlated negatively with the number of tryptase MCs in the nonlesional granular layer and with IL-6 MCs in both the nonlesional and lesional granular layers. CONCLUSION: (Pro)filaggrin expression is decreased in AD and is reversely associated with MC tryptase and IL-6. However, it does not associate with disease severity, and it was also decreased in psoriasis.

Renal interstitial mast cell count is significantly higher in membranoproliferative glomerulonephritis than in class IV lupus nephritis.

Lupus nephritis (LN) is a severe manifestation of systemic lupus erythematosus; in LN class IV morphologic lesions may be similar to the lesions in primary membranoproliferative glomerulonephritis (MPGN). The aim of the study was to compare the counts of tryptase-positive and chymase-positive mast cells between LN class IV and MPGN. The material consisted of 61 renal biopsies: 32 with lupus nephritis class IV, and 29 with membranoproliferative glomerulonephritis. Chymase- and tryptase-positive cells were stained by immunohistochemistry and subsequently counted. The mean count of chymase-positive mast cells was 21.94 for the whole group, 12.66 for LN class IV and 32.18 for MPGN. The mean count of tryptase-positive cells was 34.94 hpf for the entire group, 22.98 for LN class IV and 48. 13 for MPGN. The differences between lupus nephritis and membranoproliferative glomerulonephritis were significant both for chymase- and tryptase-positive cells. Both chymase-positive MC counts and tryptase-positive MC counts correlated with relative interstitial volume (RIV) (R=0.35 and R=0.28, respectively) and with creatinine level (R=0.35 and R=0.43, respectively). There was also a significant correlation between age, creatinine level and RIV (R=0.28 and R=0.26, respectively).

A positive correlation between immunohistochemical expression of CD31 and mast cell tryptase in odontogenic tumors.

In this study, we compared mast cell tryptase and CD31 expression between odontogenic tumors with the aim of predicting the clinical behavior of these lesions at the time of initial biopsy. We also evaluated the correlation between mast cell tryptase and CD31 expression to clarify the role of mast cells (MCs) in the growth of odontogenic tumors. Immunohistochemical staining with anti-MC tryptase and anti-CD31 antibodies was performed on 48 cases of odontogenic tumors including solid ameloblastoma (SAM), unicystic ameloblastoma (UAM), odontogenic myxoma (OM), cystic calcifying odontogenic tumor (CCOT) and adenomatoid odontogenic tumor (AOT). Ten high power fields were analyzed for each sample. Total MC count was significantly increased in SAM compared to other odontogenic tumors (p<0.05). Microvessel density was statistically higher in SAM and AOT compared to remaining odontogenic tumors (p<0.05). A significant correlation was observed between MCs and microvessels in odontogenic tumors (p=0.018, r=0.34). Our findings suggest a role for MCs in aggressive clinical behavior of odontogenic tumors. The significant correlation found between MC count and microvessel density in odontogenic tumors is in agreement with the theory of participation of MCs in tumor progression. Targeting MC activity may represent an important nonsurgical therapeutic approach, especially for aggressive odontogenic tumors.

Increased numbers of tryptase-positive mast cells in the healthy and sun-protected skin of tobacco smokers.

BACKGROUND: Tobacco smoking may cause skin aging through mast cell proteinases. OBJECTIVE: To compare the numbers of mast cells showing tryptase and chymase in the healthy-looking skin of smokers and non-smokers. METHODS: The study subjects consisted of 80 males, 42 of whom were smokers and 38 non-smokers. A skin biopsy from the medial arm was processed for immunohistochemical staining of tryptase and chymase, as well as chymase inhibitors alpha-1-proteinase inhibitor (alpha-1-PI) and alpha-1-antichymotrypsin (alpha-1-AC). RESULTS: The number of tryptase(+) mast cells was significantly higher in the smoker group (84 ± 32 cells/mm(2)) than in the non-smoker group (70 ± 32 cells/mm(2)) (p = 0.044). Likewise, the number of chymase(+) mast cells was higher in the smoker group (89 ± 20 vs. 80 ± 22 cells/mm(2)), though statistical significance was not reached (p = 0.07). No significant difference was observed in alpha-1-PI(+) and alpha-1-AC(+) cells. CONCLUSION: Especially tryptase, but probably also chymase, may have an influence on the skin of smokers, such as wrinkling and aging.

Mast cell phenotype in benign and malignant tumors of the prostate.

The molecular phenotypic heterogeneity of mast cells (MCs) makes them attractive as potential therapeutic targets in anti-cancer adjuvant therapy. Mast cell aggregations observed in tumors suggested their involvement in tumor pathogenesis. Despite several studies using mast cell tryptase, MCs' involvement in the progression of prostate tumors has not been demonstrated. The aim of our study was to identify and quantify the phenotypic heterogeneity of MCs in prostate lesions. Our study included 7 cases of normal prostate, 25 cases of benign epithelial hyperplasia and 64 cases of prostate carcinoma. MCs were immunohistochemically assessed using three markers: tryptase, chymase and CD117. Two immunophenotypes of MCs were identified in benign lesions: tryptase+/CD117+/chymase- and tryptase-/chymase+/CD117+, located in peritumoral areas. Intratumoral MC phenotype of malignant lesions was characterized by tryptase+/chymase+/CD117+, while in the peritumoral areas three different MCs phenotypes were identified: tryptase+/chymase+/CD117-, tryptase+/CD117+/chymase- and chymase+/CD117+/tryptase-. Our results suggest the correlation of chymase positive MCs of the peritumoral areas and CD117 positive MCs of the intratumoral areas with tumor grade.

Increased number of non-degranulated mast cells in pancreatic ductal adenocarcinoma but not in acute pancreatitis.

Increasing evidence indicates that tumor microenvironment (TME) is crucial in tumor survival and metastases. Inflammatory cells accumulate around tumors and strangely appear to be permissive to their growth. One key stroma cell is the mast cell (MC), which can secrete numerous pro- and antitumor molecules. We investigated the presence and degranulation state of MC in pancreatic ductal adenocarcinoma (PDAC) as compared to acute ancreatitis (AP). Three different detection methods: (a) toluidine blue staining, as well as immunohistochemistry for (b) tryptase and (c) c-kit, were utilized to assess the number and extent of degranulation of MC in PDAC tissue (n=7), uninvolved pancreatic tissue derived from tumor-free margins (n=7) and tissue form AP (n=4). The number of MC detected with all three methods was significantly increased in PDAC, as compared to normal pancreatic tissue derived from tumor-free margins (p<0.05). The highest number of MC was identified by c-kit, 22.2∓7.5 per high power field (HPF) in PDAC vs 9.7∓5.1 per HPF in normal tissue. Contrary to MC in AP, where most of the detected MC were found degranulated, MC in PDAC appeared intact. In conclusion, MC are increased in number, but not degranulated in PDAC, suggesting that they may contribute to cancer growth by permitting selective release of pro-tumorogenic molecules.

Amniotic fluid embolism induces uterine anaphylaxis and atony following cervical laceration.

Amniotic fluid embolism (AFE) is a rare, high-risk obstetric complication primarily found in the lungs and potentially related to anaphylaxis. Tryptase release from the mast cell reflects anaphylaxis. Case report and findings: A female, aged over 40 years, presented with uterine atony and lethal hemorrhage after induced vaginal labor. Cervical laceration was accompanied by severe hemorrhage. Stromal edema and myometrial swelling were consistent with uterine atony. Alcian blue staining and zinc coproporphyrin immunostaining disclosed AFE, which was more prominent in the uterus than in the lungs. Tryptase immunostaining was diffuse and prominent around the activated mast cells (halos) in the uterus, including the cervix. Similar distribution of findings on the AFE markers, tryptase halos, complement receptor C5aR, and atony in the uterus suggested the causality of AFE to anaphylaxis, complement activation and atony. It is probable that disseminated intravascular coagulation (DIC), induced by AFE, uterine atony and cervical laceration, caused the lethal hemorrhage. It is likely that AFE, in association with cervical laceration, induces uterine anaphylaxis, complement activation, atony, DIC and lethal hemorrhage.