Potentially fatal interstitial lung disease can occur in clinically amyopathic dermatomyositis

Abstract

Interstitial lung disease (ILD) is a potentially fatal complication of the idiopathic inflammatory myopathies occurring in 5% to 40% of patients with classic dermatomyositis (DM).1Hirakata M Nagai S Interstitial lung disease in polymyositis and dermatomyositis.Curr Opin Rheumatol. 2000; 12: 501-508Crossref PubMed Scopus (125) Google Scholar, 2Douglas WW Tazelaar HD Hartman TE Hartman RP Decker PA Schroeder DR et al.Polymyositis-dermatomyositis-associated interstitial lung disease.Am J Respir Crit Care Med. 2001; 164: 1182-1185Crossref PubMed Scopus (469) Google Scholar However, it is not generally appreciated that ILD can also occur in subsets of DM that lack hallmark clinical features such as muscle weakness (eg, clinically amyopathic DM [C-ADM]). C-ADM (synonym, DM siné myositis) is a subset of idiopathic inflammatory myopathies in which the hallmark cutaneous manifestations of DM (ie, DM-specific skin disease [DMSSD]) are present for 6 months or longer without the development of clinically evident muscle weakness.3Sontheimer RD Cutaneous features of classical dermatomyositis and amyopathic dermatomyositis.Curr Opin Rheumatol. 1999; 11: 475-482Crossref PubMed Scopus (161) Google Scholar, 4Sontheimer RD Would a new name hasten the acceptance of clinically amyopathic dermatomyositis (dermatomyositis siné myositis) as a distinctive subset within the idiopathic inflammatory dermatomyopathies spectrum of clinical illness?.J Am Acad Dermatol. 2002; 46: 626-636Abstract Full Text Full Text PDF PubMed Scopus (357) Google Scholar, 5Caproni M Cardinali C Parodi A Giomi B Papini M Vaccaro M et al.Amyopathic dermatomyositis: a review by the Italian group of immunodermatology.Arch Dermatol. 2002; 138: 23-27Crossref PubMed Google Scholar Although previously thought to be quite rare, more than 300 cases of C-ADM have now been published. Among these cases, we were surprised to find 34 published cases of often fatal ILD occurring in patients having DMSSD but no muscle weakness (Table I). Many of these reports have been published in languages other than English, especially Japanese. Not all of these cases meet the classification criteria for C-ADM because DMSSD in some cases had been present for less than 6 months when ILD presented clinically. However, these cases were included in the present analysis because they do represent ILD occurring in the context of DMSSD without the presence of muscle weakness.Table ISummary of published cases of interstitial lung disease occurring in patients with dermatomyositis-specific skin disease but no muscle weaknessClinical featuresAll cases (N = 34)Japanese cases (n = 27)Other cases (n = 7)Mean age, y (range)53.4 (10-88)54.5 (23-84)49.0 (10-88)Median age, y525247Male/female ratio14:2011:163:4C-ADM subclassification†ADM-14; HDM-4ADM-11; HDM-3ADM-3; HDM-1Mean interval (y) between onset of DMSSD and diagnosis of ILD (range)1.49 (0.08-18.0)1.06 (0.12-4.0)3.42 (0.08-18.0)Median interval (y) between onset of DMSSD and diagnosis of ILD0.830.830.65Fatal outcome from ILD (%)18/34 (53)16/27 (59)2/7 (29)Antinuclear antibody (%)6/27‡(22)5/22 (23)1/5 (20)Myositis-specific antibodies (Jo-1)0/260/230/3ESR mean value, mm/h44 (24 tested)52 (19 tested)35 (5 tested)Associated malignancy (%)1/34 (3)1/27 (4)0/7*Countries from which non-Japanese cases were reported: Australia (1), Brazil (1), Malaysia (1), Korea (1), United States (1), West Indes (1), Yugoslavia (1). †C-ADM can be subclassified as follows: ADM (DMSSD for at least 6 months or longer without muscle weakness, normal muscle enzymes, and no other laboratory or radiologic evidence of muscle inflammation [eg, electromyography, muscle biopsy, muscle spectroscopy]); HDM (DMSSD for at least 6 months or longer without muscle weakness, normal muscle enzymes but some degree of other clinically silent laboratory or radiologic evidence of myositis). The key distinguishing feature of C-ADM is the fact that such patients display DMSSD for atypically prolonged periods of time without accompanying muscle weakness that is typical of classical DM. (Not all patients included in this analysis could be subclassified as either ADM or HDM since some had DMSSD for less than 6 months at the time of onset of their ILD.) ‡Number positive or abnormal/number tested.ADM, Amyopathic dermatomyositis (DM); C-, clinically; DMSSD, DM-specific skin disease; ESR, erythrocyte sedimentation rate; HDM, hypomyopathic DM; ILD, interstitial lung disease. Open table in a new tab ADM, Amyopathic dermatomyositis (DM); C-, clinically; DMSSD, DM-specific skin disease; ESR, erythrocyte sedimentation rate; HDM, hypomyopathic DM; ILD, interstitial lung disease. In addition to the 34 published cases summarized in Table I, we are aware of several other such cases reported in abstract form (5 cases), on Internet Web sites (2 cases, both fatal), and by personal communication (1 case, fatal). Thus, there can be little doubt that clinical evidence of muscle weakness need not be present for the development of potentially fatal, DM-associated ILD. Failure to recognize this clinical constellation can delay diagnosis and institution of proper treatment and, thereby, have disastrous NO LABELPublished online March 11, 2003