Discussion
IPAF is not really a diagnosis, but a term used for patients with
idiopathic interstitial pneumonia and features of autoimmunity who did
not fall within the criteria of a connective tissue disease (4). In
2015, a multidiscipinary task force proposed classification criteria for
IPAF. Those criteria are organised around features of three domains : a
clinical domain consisting of specific extra-thoracic features, a
serologic domain consisting of specific autoantibodies, and a
morphologic domain consisting of specific chest imaging, histopathology
or pulmonary physiologic features (2). According to Fischer et al., our
patient had the criteria with an idiopathic interstitial pneumonia based
on the CT scan, ANA > 1 :320 titre (anti-RNP and anti-JO1
identification) and diffuse polyarthralgia. Furthermore, all alternative
etiologies were excluded and he did not meet criteria of a defined
connective tissue disease. We also note that CK levels were in standards
and the patient did not present myalgia despite positive anti-JO1
identification.
There is no specific treatment as IPAF is a research consensus statement
and not a well-defined entity. Management consists of global care with
pulmonary rehabilitation, oxygen therapy if necessary, prevention of
infection and bone health assessment (1). Corticosteroids and
immunosuppressive agents are usually used. For example, azathioprine and
mycophenolate mofetil (MMF) are associated with improvement or
stabilization of lung function (1). In this case, the patient received a
combination of corticosteroids and MMF but this was not enough. He was
considered as a patient with refractory interstitial lung disease (ILD)
and Rtx treatment was given as salvage therapy with an improved
therapeutic response. A retrospective study indicates efficacy of Rtx in
patients with Antisynthetase Syndrome (AS) and ILD. Indeed, this study
demonstrated a reduction in ILD extent post therapy (5). Doyle et al.
also showed that in ILD with AS, the principal indication for Rtx use
was recurrent or progressive ILD due to failure of other agents
resulting in stability or improvement in pulmonary function or severity
of ILD on CT scan with a good tolerance of the treatment (6).
In 2012, Keir et al. showed the benefits of using Rtx as life-saving
therapeutic intervention in severe CTD-ILD with failure to conventional
immunosuppression. In his study, patients improved pulmonary function
with Rtx (3). In 2016, Lepri et al. demonstrated that Rtx may help to
control the course of ILD in CTD producing a stabilisation of lung
involvement in systemic sclerosis and mixed connective tissue disorders
(7).
According to Saunders et al., there are no approved therapies for
CTD-ILD : cyclophosphamide is the main therapy for patient with severe
or progressive CTD-ILD but observationnal studies suggested that Rtx is
an effective rescue therapy for refractory CTD-ILD (8).
Recently, Atienza-Mateo et al. demonstrated that Rtx was a good
therapeutic option to preserve lung fonction in patients with IPAF (9).