D1.55 - Assembling the Idiopathic Anaphylaxis Puzzle: Where was the secret key for Idiopathic anaphylaxis’s box?

Anaphylaxis is a life-threatening condition characterized by sudden onset symptoms involving different organ systems and requiring immediate medical intervention. The incidence of hospitalization due to food- and drug-induced anaphylaxis has been increasing globally in recent years. The diagnosis of anaphylaxis is  based mainly on  clinical evaluation. Idiopathic anaphylaxis (IA) is a diagnosis of exclusion. This case report aims to summarize the diagnostic approach for IA and emphasizes the importance of identifying the triggering agent to prevent recurrent, potentially fatal episodes and improve patients' quality of life.

Case presentation:

A 54-year-old male was referred to our tertiary care center for evaluation of recurrent episodes of spontaneous anaphylaxis. Over a 6-month period, the patient reported five distinct episodes of generalized erythema, pruritus, conjunctivitis, sweating, non-bloody diarrhea, hypotension, and dizziness, without loss of consciousness. Serum tryptase levels were elevated during acute episodes, while baseline levels remained within normal limits. Emergency treatment consisted of intravenous corticosteroids and antihistamines, one of them required hospitalization. The patient was on regular therapy with β-blocker for hypertension and an alpha blocker for benign prostatic hyperplasia. Other medications taken as needed included H2-blockers and analgesics. At the time of evaluation, the patient experienced another acute episode of symptoms additionally with hemodynamic instability. Based on the disease history, frequency of episodes, severity and potential risk of fatal outcome, the patient was referred for further tests for mastocytosis. 

Results:

Initial detailed history failed to identify specific triggers, such as food, drugs, other allergens, or cofactors,e.g., alcohol, exercise, non-steroidal anti-inflammatory drugs (NSAIDs), spices, mammalian meat, latex). Additional information from family members revealed NSAIDs intake prior most of the anaphylactic episodes which the patient failed to recognize as potential trigger. Skin prick testing was not performed due to the acute nature of the episode at the time of evaluation. Serum tryptase levels during last episode were normal, and molecular allergy testing revealed no clinically significant findings. Genetic testing for c-kit mutations and histopathological bone marrow examination excluded mast cell monoclonal disorders and mastocytosis.

Discussion:

Anaphylaxis continues to pose a significant burden on patients and healthcare systems, presenting a challenge both in terms of diagnosis and management. In this case, a provisional diagnosis of IA was made based on clinical history and laboratory results. However, only precise communication with patient and his family was able to reveal the triggering agent, nimesulide, a NSAID. This case underscores the crucial importance of detailed investigation in diagnosing anaphylaxis and highlights the role of accurate diagnosis in preventing future episodes and improving patients’ quality of life.