Abstract

The novel dendritic cell/acute myeloid leukemia (AML) fusion vaccine is produced from cryopreserved patient-derived autologous leukemia blasts and donor-derived dendritic cells, with the aim of stimulating the expansion of donor T cells to prevent AML relapse. A recent series showed that vaccine site reactions are very common (10/11 patients), however the histopathology of this reaction has not been described. In this abstract we describe the features of such a reaction that developed at the vaccine injection site in the left thigh of a 58-year-old male with intermediate risk AML status-post haploidentical stem cell transplant. The site became indurated and erythematous 3 days after administration clinically characterized as a grade 2 vaccine site reaction. Punch biopsy revealed epidermal spongiosis with acanthosis, patchy parakeratosis containing occasional neutrophilic microabscesses, scattered Langerhans cell microabscesses in the upper epidermis, tapering superficial to mid-dermal perivascular lymphocytic infiltrate with occasional admixed eosinophils, and upper dermal edema. The overall picture was that of a localized cutaneous hypersensitivity reaction. It is not known what component of the vaccine triggered the reaction. The patient was treated with oral diphenhydramine and betamethasone 0.05% ointment, with significant improvement of the vaccine site reaction within days.

Financial Disclosure:
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