Indolent systemic mastocytosis (SM) was found after a severe anaphylactic reaction to intravenous methylprednisolone succinate as reported in a letter to the editor in Allergology International.

The patient experienced swelling of the throat, hypotension, and shock within 2 minutes of administration of the treatment for an episode of idiopathic urticaria. Acute serum tryptase levels during the anaphylactic episode were indicative of mast cell activation with a level of 63 μg/L and a baseline of 44.8 μg/L. No cutaneous symptoms of mastocytosis were observed, however.

“Sodium succinate hypersensitivity is rare but should not be overlooked as it might entail a severe risk for drug-induced anaphylaxis. In the presence of severe, mast cell-triggered anaphylaxis measurement of baseline serum tryptase is of help in identifying patients with possible concomitant (clonal) mast cell disorder,” the authors said.

Subsequent evaluation using skin prick tests and intradermal tests with a series of different steroidal treatments revealed reactions to methylprednisolone sodium succinate and hydrocortisone sodium succinate.

No reactions were observed for methylprednisolone acetate, dexamethasone sodium phosphate, triamcinolone acetonide, and betamethasone sodium phosphate plus betamethasone dipropionate, indicating a reaction to the succinate moiety.

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Using basophil activation tests, the allergic responses were replicated with the basophils upregulating the expression of CD63 and releasing histamine in response to the glucocorticoids containing succinate.

Fluorescent enzyme immunoassay revealed elevated specific immunoglobulin-E levels to methylprednisolone-21-sodium succinate compared to healthy controls (0.15 kUA/L vs <.10 kUA/L). The patient was then challenged orally with methylprednisolone and intramuscularly with betamethasone sodium phosphate plus betamethasone dipropionate. Both challenges were uneventful, as expected.

Bone marrow analysis found no aggregates of abnormal mast cells after tryptase staining, however, flow cytometry of the marrow cells did find aberrant CD25- and CD2-expressing mast cells. A D816V mutation of the KIT gene with an allele burden of .071% was found in the analysis of the bone marrow aspirates leading to a diagnosis of SM. Further workup found no B- or C-findings or associated neoplasms, indicating a final diagnosis of indolent SM.

“Diagnosis of [indolent SM] was made on basis of 4 minor criteria in the absence of mast cell infiltrates on bone marrow examination, highlighting the need for highly sensitive techniques in the diagnostic workup,” the authors said.

The patient in the study was 65 years old and had a history of arterial hypertension, appendectomy following appendicitis, and transurethral resection of a transitional cell carcinoma of the bladder.


Van Mieghem E, Beyens M, Van Gasse AL, Verlinden A, Ebo DG, Sabato V. IgE-mediated anaphylaxis to methylprednisolone succinate in a patient with indolent systemic mastocytosis. Allergol Int. Published online July 9, 2022. doi:10.1016/j.alit.2022.06.004