When Less Could be More: Successful Treatment of Granulomatous Lymphocytic Interstitial Lung Disease with Azathioprine.

Introduction: Interstitial lung disease is a major complication in patients with common variable immunodeficiency. There are some publications that try to shed light on the pathophysiology of this non-infectious complication, most of them highlight the role of follicular T cells and CD21^low B cells. Moreover, there are no guidelines based on randomized controlled studies on the treatment of patients with interstitial lung disease and the published case series or small uncontrolled studies describe a wide range of response rates to treatment. In this scenario, the decisions are based on expert opinion rather than on robust scientific evidence. This could lead to potential biases associated with expert opinion based on a small number of patients.

Case description: We present the case of an adult patient with common variable immunodeficiency and interstitial lung disease. He did not receive rituximab due to an adverse reaction and underwent treatment with azathioprine, achieving prolonged remission after treatment discontinuation.

Discussion: If T-cell involvement could be the main underlying cause of this complication, treatment targeting T-cells may possibly be an effective therapeutic option. Our case, complemented with a physiopathology review, suggests a beneficial effect of azathioprine that warrants further research.

Conclusion: It is important to keep in mind that patients with common variable immunodeficiency are a heterogeneous group, so no single treatment will be the best for all of them. It is necessary to review the rationale for the increasing use of anti-CD20 drugs in non-infectious complications in patients with common variable immunodeficiency. Such use is based on expert recommendations and not on randomized, controlled studies with quantitative endpoints.

Learning points: There are no guidelines based on randomized controlled studies on the treatment of patients with common variable immunodeficiency and interstitial lung disease.The use of rituximab in the treatment of various non-infectious manifestations in patients with common variable immunodeficiency, including interstitial lung disease, could be the result of potential biases associated with expert opinion based on a small number of patients.T-cell involvement could be the main underlying cause of this complication so treatment targeting T-cells may possibly be an effective therapeutic option.