So much about dermatomyositis (DM) has intrigued me since medical school. Over the years, I have probably read more about this disease than any other malady. I am always amazed how I much more there is to learn.
There were two reports about DM in the September issue of JAMA Dermatology. One case was that of a 60+ year old woman who suffered a stroke 2 years prior to the rash, causing right-sided paralysis. She developed characteristic features of DM, with scalp and periocular violaceous erythema. Gottron papules (confirmed histologically by the presence of interface dermatitis) and periungual erythema were noted on the left hand only. Kurtzman et al hypothesized that the classical lesions appeared only on the left hand because of stretch and mechanical trauma, which could not have occurred on her immobile right arm. Although a neurologic influence could not be ruled out, it was felt to be unlikely (1). This theory is certainly plausible, given the fact that Gottron papules are characteristically over bony prominences; presumably there is some traumatic role in the pathogenesis of these lesions.
Bernet et al described an “ovoid palatal patch”, characterized by a well-demarcated, arciform erythematous patch of the hard palate in 18 of 45 patients with DM. A biopsy from one patient demonstrated interface dermatitis with a thickened basement membrane and mucin, consistent with DM. Interestingly, 15 of the 18 patients had antibodies to TIF1ϒ; this was highly statistically significant, as none of the patients with other autoantibodies had this lesion. TIF1ϒ has been associated with malignancy – in this article the association with cancer did not reach significance. The authors recommended further studies to determine whether or not the oval palatal patch in DM may be used to predict outcomes such as cancer or amyopathic disease (2). While one cannot argue with the possibility of TIF1ϒ having some role in the pathogenesis, I would recommend looking carefully at the palates of those with this patch. Look at the clinical image – that patient has an impressive torus palatinus, with the erythema being on the most prominent aspect. My hypothesis is that that this ovoid palatal patch is akin to a Gottron lesion, due to the trauma of eating. Perhaps the TIF1ϒ antibody is a predisposing factor.
In honor the upcoming baseball playoffs, I would like to paraphrase a line heard at stadiums pre-smart phone: “Getcha scorecard! You can’t tell the antibodies without a scorecard”. (It is my understanding that keeping score at a baseball game – K for strikeout; a 5-4-3 double play, etc. – is a lost art). For those of us, including myself, who have trouble remembering the implications of the increasing number of autoantibodies in DM, please read the following abstract by Fujimoto et al (3).
In dermatomyositis, disease-specific autoantibodies now cover more than 70% of patients. These autoantibodies closely correlate with distinct clinical manifestations. In the past few years, extensive evidence has been accumulated on clinical significance of dermatomyositis-specific autoantibodies including autoantibodies against melanoma differentiation antigen 5 (MDA5), transcriptional intermediary factor 1 (TIF1), nuclear matrix protein 2 (NXP2), and small ubiquitin-like modifier activating enzyme (SAE).
Anti-MDA5 antibodies are found with high specificity in clinically amyopathic dermatomyositis presenting rapidly progressive interstitial lung disease (ILD) especially in Asian population. Similar tendency has been reported in the US/Europe, although the frequency of positivity and the type of ILD may differ. Anti-TIF1 antibodies are present in juvenile and adult dermatomyositis patients with close correlation with malignancy in adult population. Anti-NXP2 antibodies share similar phenotype with anti-TIF1 antibodies, except that anti-NXP2 antibodies are associated with calcinosis and severe muscle disease. Although numbers are still small, patients with anti-SAE antibodies tend to present skin disease first and then progress to muscle weakness with systematic symptoms including dysphagia. Moreover, distinct cutaneous manifestations and muscle histopathology findings for each autoantibody have been reported.
Autoantibody-based classification of dermatomyositis subsets is now a useful strategy for comprehending the heterogeneous spectrum of dermatomyositis.
- Kurtzman DJB, et al. Unilateral Gottron papules in a patient following a stroke: Clinical insights into the disease mechanisms and pathophysiology of cutaneous dermatomyositis. JAMA Dermatol 2016; 152: 1062-3.
- Bernet LL, et al. Ovoid palatal patch in dermatomyositis: A novel finding associated with anti-TIF1ϒ (p155) antibodies. JAMA Dermatol 2016; 152: 1049-51.
- Fujimoto M, et al. Recent advances in dermatomyositis-specific autoantibodies. Curr Opin Rheumatol 2016 Aug 16 [Epub ahead of print]