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Question: Do you have any experience with COVID-19 and indolent systemic mastocytosis marrow proven tryptase stable at 50 using cromolyn, H1/H2 blockers and ketotifen for flares? Patient is MD and worried about risk of exposures in practice and in particular risk of cytokine storm.

Answer: The following was provided by a mastocytosis expert: 

There is limited experience with indolent systemic mastocytosis and COVID-19 infections. At our Mastocytosis Center we had two patients with tryptase of 150 ng/ml and bone marrow aggregates and positive KIT D816V mutation confirming the WHO criteria who presented mild to moderate cases. One woman who was not hospitalized and had the classical presentation with fever, dry cough and shortness of breath for 7 days duration, and a male with a moderate presentation with desaturation in the 80 percentage range, with a short hospitalization and no intubation and who is back home in good health. He required supplemental oxygen for few days. Both patients continued mast cell controller medications throughout the infection and did not present any cytokine storm-like reactions. The male who required hospitalization was treated with steroids and neither had a mast cell activation episode or anaphylaxis during the infection. Mast cells have been shown by single cell RNA analysis to have ACE2 receptors which is the required attachment site of SARS-CoV-2 and therefore can become infected (reference below). Whether mutated mast cells with KIT D816V mutation have increased or decreased ACE2 receptor expression is not known. Based on this limited experience, patients with indolent systemic mastocytosis are not at risk for more severe presentations of COVID-19 infection and should remain on mast cell controller medications throughout the infection.

Xu H, Zhong L, Deng J, et al. High expression of ACE2 receptor of 2019-nCoV on the epithelial cells of oral mucosa. Int J Oral Sci. 2020;12(1):8. Published 2020 Feb 24. doi:10.1038/s41368-020-0074-x


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