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Objectives: To describe the clinicopathological and genetic characteristics of mast cell tumours in dogs less than 12 months old. Materials and Methods: Retrospective review of dogs aged less than 12 months when diagnosed with mast cell tumours at three referral hospitals in the UK. Results: Sixteen pure‐bred dogs were included, of which 11 were female. The median age at first presentation and diagnosis were 7.6 and 9 months, respectively. In 13 dogs the mast cell tumours were cutaneous and in three they were subcutaneous. Four cutaneous mast cell tumours were described as high‐grade (Patnaik or Kiupel) and nine were Patnaik grade II; three had mitotic index of >5 in 10 high‐power fields. Of the three subcutaneous tumours, two had an infiltrative growth pattern and one had mitotic index of 10 per 10 high‐power fields. Of 10 tested dogs, seven had c‐kit mutations in exon 11 and Ki‐67 score was above the cut‐off value in nine. Four of 12 cases showed evidence of metastasis in the regional lymph nodes. After varying treatment protocols, all patients were alive and disease free at a median of 1115 days after diagnosis. Clinical Significance: The prognosis of mast cell tumours in dogs less than a year old appears better than the adult counterparts, even without extensive treatment. [ABSTRACT FROM AUTHOR]

Background: IL-25 is thought to participate in allergic inflammation by propagating T h 2-type responses. Objective: To address the hypothesis that allergen provocation increases expression of IL-25 and its receptor IL-25R in the asthmatic bronchial mucosa and skin dermis of atopic subjects. Methods: Sequential single and double immunostaining was used to evaluate the numbers and phenotypes of IL-25 and IL-25R immunoreactive cells in bronchial biopsies from mild atopic subjects with asthma (n = 10) before and 24 hours after allergen inhalation challenge and skin biopsies from atopic subjects (n = 10) up to 72 hours after allergen subepidermal injection. Results: IL-25 immunoreactivity was expressed by a majority of epidermal cells in both organs at baseline and was not further augmented by challenge. IL-25R immunoreactive cells were rare in the epidermis before or after challenge. Allergen challenge was associated with significantly (P < .01) increased expression of IL-25 and IL-25R immunoreactivity in the submucosa of both organs. IL-25 immunoreactivity colocalized with eosinophils, mast cells, and endothelial cells, whereas IL-25R immunoreactivity colocalized with eosinophils, mast cells, endothelial cells, and T lymphocytes. In both organs, correlations were observed between increases in IL-25 expression and the magnitudes of the late-phase allergen-induced clinical responses. Conclusion: Allergen provocation induces functionally relevant, increased expression of IL-25 and its receptor in the asthmatic bronchial mucosa and dermis of sensitized atopic subjects. In addition to T cells, eosinophils, mast cells, and endothelial cells are potential sources and targets of IL-25 in the course of allergic inflammation. [ABSTRACT FROM AUTHOR]

Background Superficial acral fibromyxoma (SAF) remains poorly recognized by general pathologists and dermatopathologists, partly attributable to its relatively uncommon occurrence and recent documentation. Objectives To examine a series of SAF and document the U.K. experience with this new entity. Methods We reviewed 771 tumours reported between 1970 and 2006 in seven different U.K. hospitals and coded as myxoma, not otherwise specified (NOS), fibroma (NOS) or dermatofibroma (NOS) presenting at acral sites. Forty-one cases of SAF were studied. Results The patients comprised 27 men and 14 women, age range 19–91 years (mean 50, median 47), presenting with a solitary mass or nodule with a mean size of 1·92 cm. The common clinical sites were the toes ( n = 29) and fingers ( n = 11) as well as the palm ( n = 1), with more than 75% of cases close to or involving the nail bed. All cases presented with a painless mass except for four cases where pain was the presenting complaint. A history of trauma was reported in only two cases. Histologically, all cases presented as proliferation of spindle-shaped and/or stellate cells with a storiform and fascicular pattern embedded in a fibromyxoid/collagenous stroma with conspicuous mast cells. Multinucleated cells were observed ( n = 22), increased number of blood vessels in the stroma and extravasation of red blood cells ( n = 4). The characteristic immunophenotype was CD34+, CD99+/−, epithelial membrane antigen+ focally/−, S100−, desmin−, smooth muscle actin−, HMB45− and cytokeratin−. Conclusions We describe a large series of 41 cases of SAF showing that it is a distinct entity with typical clinical, histological and immunohistochemical features. Follow-up was available only in 12 patients, precluding a firm comment on recurrence. However, complete excision and follow-up review is recommended. [ABSTRACT FROM AUTHOR]

The article presents abstracts of a symposium held at Robinson College, Cambridge, Great Britain from December 14-16, 1994. Functional heterogeneity of human mast cells was discussed during the symposium. Mast cells heterogeneity is well defined in the rodent, where two distinct phenotypes have been identified. Releasability is a term that has been applied to several notable features of the response of human basophils and mast cells to receptor-mediated stimulation. Interest in this area comes from several directions. These include interest in whether differences in cellular sensitivity to simulation.

Focuses on the development of urticaria in Great Britain. Implication of the concept of neurosis for the function of vasomotor nerves supplying the small blood vessels; Role of mast cells as the source of mediators in urticaria; Relationship between urticaria and thyroid disease.

Reports on the representation of the role of the several classes of candidate mediators of inflammation in human skin based from a study in Great Britain. Capacity of inflamed tissues to retain their vitality enabling development of the classical features of inflammation; Contribution of the tissue mast cell and subsequent realization that it was a source of important molecular mediator to the pharmacological research in inflammation; Role of histamine as a chemical mediator in the inflammatory response.

Background: Hereditary alpha-tryptasemia (HAT) is a genetic trait caused by an increased alpha-tryptase tryptase alpha/beta 1 gene copy number. Basal serum mast cell tryptase (MCT) level is typically greater than or equal to 8.0 ng/mL., Objectives: To study the clinical disease spectrum of HAT and determine its UK prevalence., Methods: Droplet digital PCR was used to determine tryptase alpha/beta 1 copy number in 432 DNA samples from an unselected UK birth cohort and in 70 patients referred with a basal MCT level greater than 8 ng/mL. Baseline MCT concentrations and clinical presentation were also assessed in 4283 samples sent to a regional immunology laboratory., Results: Duplication in alpha copy number was present in 5% of the unselected British birth cohort, with all affected individuals having a basal MCT level of greater than or equal to 8.0 ng/mL. Basal MCT levels of greater than or equal to 8.0 ng/mL were also found in 5% of the 4283 individuals referred for MCT testing because of clinical symptoms. In 70 patients confirmed to have HAT (79% with a duplication; 21% with a higher alpha gene copy number), urticaria/angioedema (51%), skin flushing (41%), food intolerances (39%), and altered bowel habits (36%) were common presenting complaints. However, clinical manifestations were not more common in patients with gene triplications or quintuplications than in those with duplications. Some immediate family members with the same genetic trait and high basal MCT levels were asymptomatic., Conclusions: Five percent of people in the United Kingdom may have HAT. The diagnosis should be considered when basal MCT level is greater than or equal to 8 ng/mL. HAT has variable clinical penetrance. It may modify the expression of multifactorial allergic diseases rather than directly cause specific phenotypes., (Copyright © 2020 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Dr James Riley, an honours graduate of Edinburgh University, had to give up a surgical career because of an affliction of his hands, and instead became a radiotherapist in Dundee. He had always been fascinated by past heroes of medical research, and set out to carve his own niche in the study of mast cells. In the early 1950s, no one knew what their function was other than the mast cell granules being the storehouses of heparin. Riley and pharmacologist Dr Geoffrey West went on to galvanise this area of study by showing in a notable series of experiments that the mast cell granules are also the main repository of histamine, a key participant in allergic and anaphylactic reactions. Riley's story is a prime example of the ability to make cutting-edge discoveries even in the face of modest facilities., Competing Interests: No conflict of interests declared

The article presents a medical research in Great Britain on the ins and outs of calcium ions signalling in mast cells. It is said that the influx of calcium ions on lymphocytes is widely recognized as being crucial for the proper functioning of mast cells. Moreover, the paper also features two studies on the role of the molecules in regulating mast cell function and reveals a key role for store-operated calcium ions influx in mediating mast-cell function and allergic reaction.