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. 2024 Oct;51(10):799-806.
doi: 10.1111/cup.14691. Epub 2024 Jul 15.

Clinically amyopathic dermatomyositis: Clinical, laboratory, and histopathological features

Xintong Wang  1 , Ellen De Moll  2 , Merav Koschitzky  3 , Nahla Shihab  4 , Saakshi Khattri  5 , Robert Phelps  5
Affiliations

Clinically amyopathic dermatomyositis: Clinical, laboratory, and histopathological features

Xintong Wang et al. J Cutan Pathol. 2024 Oct.

Abstract

Background: Despite the advancements in the categorization of clinically amyopathic dermatomyositis (CADM), the classification and diagnosis of its subtypes are still challenging. The aim of our study was to describe the clinicopathological features of CADM and assess the differences between amyopathic dermatomyositis (ADM) and hypomyopathic dermatomyositis (HDM).

Methods: This retrospective study included 43 patients with CADM diagnosed at our institution from 2016 to 2020. Patients were subclassed into ADM (n = 30) and HDM (n = 13) groups to assess their clinicopathological differences.

Results: All included patients had characteristic cutaneous manifestations of dermatomyositis; 67.4% had myositis-associated auto-antibodies, including ANA (32.6%), RNP (14.0%), anti-Ro52 (9.3%), anti-p155/140 (7.0%), rheumatoid factor (7.0%), anti-NXP-2 (4.7%), anti-MDA5 (2.3%), and anti-Jo-1 (2.3%) antibodies. One patient had associated interstitial lung disease, and another patient had oral squamous cell carcinoma. The histopathological findings included mucin deposition (69.8%), telangiectasia (65.1%), lymphocytic infiltrate (48.8%), vacuolar interface dermatitis (46.5%), and epidermal atrophy (14.0%). Compared to patients with HDM, ADM patients were significantly less likely to have epidermal atrophy, 3.3% versus 38.5% (p = 0.006), and more likely to have mucin deposition, 80.0% versus 46.2% (p = 0.028).

Conclusion: We described the clinicopathological features of CADM and highlighted the distinctions between ADM and HDM dermatopathologic findings. This information may prove helpful in diagnosing ambiguous lesions.

Keywords: amyopathic dermatomyositis; clinically amyopathic dermatomyositis; hypomyopathic dermatomyositis.

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References

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Supplementary concepts