Fig. 14.9  Rapidly progressive pneumonitis in a 22 years-old patient with anti-MDA5 antibody. Very subtle ground glass opacities were observed at diagnosis (Panel a) which progressed to diffuse opacities

and acute respiratory failure within 6 weeks, despite high dose corticosteroids and cyclophosphamide (panel b). The patient’s condition required an emergency lung transplantation

series of 18 patients with respiratory muscle involvement leading to a restriction, an 83% remission rate was observed after treatment with corticosteroids or immunosuppressive therapies (azathioprine, cyclosporine) [136]. Intravenous immunoglobulin can also be rapidly effective in muscular involvement. In severe patients, close monitoring in the intensive care unit for possible noninvasive mechanical ventilation can be necessary.

Other Pulmonary Manifestations

Other pulmonary conditions can be observed during myositis, although with a lower frequency. PH can be observed with a low prevalence, as a consequence of ILD in most cases (group 3), although anecdotal cases of myositis-­ associated pulmonary arterial hypertension in the absence of ILD (group 1) were also reported [137]. Pleural effusion is also a rare complication of myositis, mostly observed in dermatomyositis.

Prognosis

Myositis-ILD is associated with signi cant morbidity and mortality. Mean overall mortality related to ILD is 14%, and retrospective studies have shown 10-year survival rates between 71 and 89%. Mortality is greatly increased in rapidly progressive ILD compared to chronic forms, with mortality at 3 months of 68% [138, 139].

The type of myositis and myositis-speci c autoantibody is correlated with outcome (Table 14.3). Thus, patients with anti-PM/Scl autoantibodies tend to have less severe lung involvement than those with anti-synthetase antibodies and present relatively low mortality related to ILD (0–11%) [104].

A recent study identi ed acute/subacute presentations of ILD, older age, lower FVC, and clinically amyopathic der-

matomyositis as predictors associated with higher mortality in myositis-ILD. In that study, more than 25% of patients died in the follow-up period [140]. HRCT pattern also seems to be related to outcome, with OP associated with a better prognosis than NSIP or UIP [141].

Moreover, treatment response and prognosis are variable among patients. Polymyositis-ILD is associated with a better response than dermatomyositis-ILD [123, 140]. An anti-­ MDA5 antibody is associated with corticosteroid resistance and poor prognosis (Fig. 14.9). Anti-aminoacyl tRNA synthetase antibodies are characterized by a greater response to corticosteroids, although associated with a greater risk of relapse (Table 14.3) [124, 142]. The use of JAK inhibitors for the treatment of myositis-ILD is of growing interest because of the potential anti-infammatory and antibrotic properties of these molecules [143], with small series and case reports suggesting that these molecules might be of interest in refractory cases and in rapidly progressive ILD [144], particularly when associated with an anti-MDA5 antibody [145].

Other Therapeutic Options in CTD-ILD

Antifbrotic Therapy

The currently available anti brotic drugs are under investigation as promising candidates for the management of CTD-­ ILD patients, mainly focusing on progressive brotic phenotypes. Recently, the INBUILD trial assessed the ef - cacy and safety of nintedanib in non-IPF progressive brosing ILDs despite conventional therapies [146]. The use of nintedanib was associated with a slower decline of lung function in patients with progressive brotic ILDs, compared to placebo, with non-signi cant differences in the ef cacy of nintedanib across ILD subgroups [146]. Additionally,