Telangiectasia macularis eruptiva perstans,a form of cutaneous mastocytosis,associated with malignant melanoma

A 62‐year‐old obese woman presented with a malignant melanoma (Stage la). In addition, she had disseminated telangiectatic macules on both thighs. Intensive rubbing of lesions resulted in wheals. Biopsy revealed increased numbers of mast cells. We diagnosed telangiectasia macularis eruptiva perstans, a rare clinical form of adult maculopapular cutaneous mastocytosis, a group which also includes urticaria pigmentosa. No evidence was found for systemic involvement. Possible associations with malignant tumors and the possible role of c‐kit mutations both in development of melanoma and mastocytosis are discussed.     

Baseline serum levels of mast cell tryptase are raised in hemodialysis patients and associated with severity of pruritus

Background: The pathogenesis of pruritus in renal disease is not yet understood. Evidence suggests that mast cells play a role; for example, the number of dermal mast cells is increased in patients on hemodialysis. Patients and methods: To investigate a possible role of mast cell tryptase in pruritus of patients undergoing chronic hemodialysis, serum mast cell tryptase concentrations were measured in blood samples taken from 93 such patients, 53 of whom also recorded the severity of their pruritus on a visual analogue scale. Results: Serum mast cell tryptase levels were above 11.4 µg/l (95^th percentile) in 84 of 93 hemodialysis patients (90.3 %). The intensity of pruritus correlated significantly (p = 0.014) with the tryptase levels, an associated not yet shown for other mast cell‐related parameters. Conclusions: Mast cells or even tryptase itself may be involved in the pathogenesis of pruritus of hemodialysis patients.     

Mast cell lines HMC‐1 and LAD2 in comparison with mature human skin mast cells – drastically reduced levels of tryptase and chymase in mast cell lines

Please cite this paper as: Mast cell lines HMC‐1 and LAD2 in comparison with mature human skin mast cells – drastically reduced levels of tryptase and chymase in mast cell lines. Experimental Dermatology 2010; 19 : 845–847. Abstract: To circumvent the costly isolation procedure associated with tissue mast cells (MC), two human MC lines, i.e. HMC‐1 and LAD2, are frequently employed, but their relation to mature MC is unknown. Here, we quantitatively assessed their expression of MC markers in direct comparison to skin MC (sMC). sMC expressed all lineage markers at highest and HMC‐1 cells at lowest levels. LAD2 cells expressed comparable high‐affinity IgE receptor α (FcεRIα) and FcεRIγ but less FcεRIβ than sMC and displayed slightly reduced, but robust FcεRI‐mediated histamine release. Only minor differences were found for total histamine content and c‐Kit expression. Huge, and to this level unexpected, differences were found for MC tryptase and chymase, with sMC >>> LAD2 > HMC‐1. Taken together, HMC‐1 cells represent very immature malignantly transformed MC, whereas LAD2 cells can be considered intermediately differentiated. Because of the minute levels of MC proteases, MC lines can serve as surrogates of tissue MC to a limited degree only.