Excessive Dynamic Airway Collapse After Entecavir Use in a Patient With Pegylated Interferon-Induced Undifferentiated Connective Tissue Disease and Entecavir Use to Prevent Hepatitis B Virus Reactivation Upon Giving Rituximab.

Pegylated interferon-alpha (PEG-IFN-α) is an antiviral medication used to treat chronic hepatitis C virus (HCV) and hepatitis B virus (HBV) infections. It may result in rare but severe side effects, such as undifferentiated connective tissue disease (UCTD) and excessive dynamic airway collapse (EDAC), which can occur as delayed complications of PEG-IFN-α-induced UCTD. In cases where these complications arise, entecavir, employed for treating HBV infection, may be considered. A 49-year-old female patient, monitored for nine years with HCV and a viral load of 1.5 million, genotype 3, and normal liver function tests (LFTs), possibly acquired the infection from her HCV-positive husband. The patient was initially treated with PEG-IFN-α (IFN-α-2b, 100 µg/week subcutaneously) and ribavirin (RBV, 500 mg/twice daily). Following the sixth injection, the patient exhibited symptoms, including shortness of breath and cough, leading to limited daily activities. Subsequent high-resolution computed tomography (HRCT) showed interstitial pneumonitis (IP) signs. She was given a high dose of steroids. Over the next two to four weeks, the patient experienced Raynaud's phenomenon, skin tightening, joint pains, and dryness of the eyes and mouth. The antinuclear antibody (ANA) test was negative, while the extractable nuclear antigen (ENA) test showed equivocal anti-Smith antibodies (6.38). Rheumatoid factor (RA) factors were mildly positive, and pulmonary function tests (PFTs) indicated a restrictive pattern. The patient was intolerant to hydroxychloroquine (HCQ) and azathioprine (Imuran) 500 mg, subsequently receiving mycophenolate mofetil 500 mg/thrice daily. Despite four years of treatment, UCTD due to PEG-IFN-α remained difficult to control; however, IP responded well to steroids. Rituximab pulse therapy was planned before the initiation; serological tests showed positive anti-HBs with a titer of 17.02, positive anti-HBc, but negative HBsAg and undetectable HBV viral load, indicating immunity to HBV due to natural infection. Given the potential for rituximab to cause immunosuppression and HBV reactivation, entecavir treatment was started and continued for 18 months. The patient was followed for another five years, during which her LFTs and viral markers showed stability. However, after nine years of PEG-IFN-α-induced UCTD disorder, she experienced a reoccurring cough but was unresponsive to steroids that were against her suspicion of a flare of IP. A subsequent dynamic CT scan detected a 75% trachea collapse while in a supine position, indicating a potential complication termed EDAC. This EDAC could not be linked to PEG-IFN-α-induced UCTD disorder or EDAC after the use of entecavir in a patient with PEG-IFN-α-induced UCTD disorder. Treatment of such complex patients requires flexible, specific treatment plans and continuous monitoring. This case emphasizes the need for caution in patients with a history of IFN-induced disease and the possibility of late effects and possible effects of the use of entecavir in a patient with PEG-IFN-α-induced UCTD. To the best of our knowledge, this is the first case reported as EDAC, a possible delayed complication of PEG-IFN-α plus ribavirin or entecavir in a patient with PEG-IFN-α-induced UCTD.