Allergen immunotherapy is commonly incorporated in the management of allergic rhinoconjunctivitis, allergic
asthma, and
insect sting hypersensitivity. It is generally safe, but systemic reactions occasionally occur, mainly of the immediate type and rarely of the delayed type. We report a case of a 50-year-old man with allergic rhinoconjunctivitis on
immunotherapy for 3 years and then received an injection from another patient's extract. The latter contained a higher concentration of house-dust mite and pollens of grasses, trees, and weeds. It also contained molds that the patient's correct extract did not have. Within half an hour, he developed a systemic reaction that resolved with symptomatic treatment. Two weeks later, he received one-half of his usual
immunotherapy dose. Within a week, he developed
urticaria,
arthralgia,
myalgia,
fever, and
lymphadenopathy. Laboratory abnormalities included
leukocytosis, elevated erythrocyte sedimentation rate,
hematuria, and elevated liver
enzymes. Oral
corticosteroid therapy for 3 weeks was ineffective. He developed significant
myalgia and apparent mood changes, attributable to
corticosteroid intake. After a single
plasmapheresis, he felt remarkable improvement within <24 hours.
Corticosteroid therapy was gradually withdrawn over 10 weeks without relapse of symptoms. This is a rare case of probable
serum sickness after the administration of a wrong
allergy immunotherapy extract. However, a causal relationship could not be proven. The response was poor to prolonged
corticosteroid therapy but was remarkable to one
plasmapheresis.