Severe Injection Site Pain in Patient with Neurofibromatosis Type 1 During Dupilumab Administration

Case at a Glance

A 25-year-old female with neurofibromatosis type 1 (NF1) and severe eosinophilic asthma experienced extreme pain during routine subcutaneous dupilumab injection, likely due to inadvertent injection into a subcutaneous neurofibroma.

Patient's Story

The patient presented with concerns about severe injection site pain during her most recent dupilumab administration. She described the pain as excruciating, causing sweating and hyperventilation - unusual for her given her high pain tolerance due to chronic conditions. The injection site required more force than typical to penetrate, and subsequently developed bruising and bleeding, which had never occurred with previous injections. The patient reported using a phone flashlight to identify and avoid visible neurofibromas before injection, but this method appeared unsuccessful in this instance. Due to fear of recurrence, she had delayed her next scheduled injection despite understanding the critical importance of dupilumab for her severe asthma management.

Initial Assessment

25-year-old female with multiple comorbidities including NF1 with tibial dysplasia, fibula pseudoarthrosis, multiple small neurofibromas, and a plexiform neurofibroma in the lower extremity. Additional conditions include severe eosinophilic asthma requiring dupilumab therapy, environmental allergies, hypothyroidism, PTSD with history of repeated head trauma, depression, and anxiety. Patient has been successfully managing dupilumab injections for 1.5 years using pre-filled syringes with spring-loaded safety mechanism.

The Diagnostic Journey

Clinical history strongly suggested inadvertent injection of a subcutaneous neurofibroma based on: increased resistance during needle insertion, severe localized pain disproportionate to typical injection discomfort, unusual post-injection bleeding and bruising, and patient's known extensive cutaneous neurofibroma burden. The patient's established pain tolerance from chronic NF1-related discomfort made the severity of this reaction particularly significant.

Final Diagnosis

Inadvertent subcutaneous neurofibroma injection during dupilumab administration in patient with NF1, resulting in severe injection site reaction and patient anxiety regarding future treatments.

Treatment Plan

Patient education on improved injection site selection techniques, including better lighting and palpation methods to identify subcutaneous neurofibromas. Consideration of rotating injection sites more frequently and potentially mapping problematic areas. Discussion of alternative injection sites including upper arms and outer thighs if patient becomes comfortable with these locations. Reassurance regarding dupilumab's critical role in preventing asthma exacerbations and hospitalization. Close follow-up to ensure treatment adherence and address injection anxiety.

Outcome and Follow-up

Patient was counseled on the likely cause of the severe injection reaction and provided with strategies to avoid future neurofibroma injections. Emphasis placed on the importance of continuing dupilumab therapy given its proven efficacy in preventing severe asthma exacerbations and hospitalizations. Patient scheduled for follow-up to assess implementation of new injection techniques and ensure treatment compliance. Consideration given to dermatology consultation for neurofibroma mapping if injection site selection remains challenging.