A 49-year-old woman was diagnosed with c-kit-positive ISM with tryptase 11.4 ng/ml (). Symptoms of SM included daily headaches, sporadic flushing, itchy throat, mild coughing, loose stools, lightheadedness, and palpitations. No cutaneous manifestations of mastocytosis were observed. She was markedly intolerant to exercise, heat, and strong emotion, all of which triggered the symptoms in spite of medications, which included ranitidine, loratadine, cetirizine, ketotifen, and montelukast. In early 2017, she experienced 5 anaphylactic reactions, requiring emergency department visits and treatment with epinephrine as well as 5 milder reactions managed at home (). Omalizumab was started at 300 mg at 4-week intervals (). On omalizumab, multisystem reactions were entirely suppressed, with only breakthrough flushing once per week, loose stools roughly twice per month, and occasional lightheadedness. A follow-up one year later revealed complete resolution of symptoms with no adverse reactions to her medications and reduced tryptase to 8.3 ng/ml ().
A 51-year-old female with c-kit-positive ISM and tryptase 31.8 ng/ml () reported intermittent episodes of shortness of breath, chest tightness, abdominal pain, and diarrhea. She had generalized lesions of urticaria pigmentosa involving her entire body, although numerous on her lower extremities. Ketotifen and ranitidine failed to control the symptoms. Omalizumab injections were started at 300 mg every two weeks (). At follow-up, her shortness of breath and chest tightness were controlled and GI symptoms had improved. Furthermore, her urticaria pigmentosa had improved and was now only observed on the lower abdomen and upper thighs. After the fourth cycle of omalizumab, she experienced an immediate multisystem reaction with respiratory distress and tongue swelling. A fifth cycle was attempted but again resulted in a similar reaction, leading to discontinuation of omalizumab therapy. At follow-up, she reported a worsening respiratory and functional status as well as 3-4 loose bowel movements per day. Basal tryptase levels had increased up to 41.2 ng/ml ().