Background The diagnosis of dermatomyositis (DM) is often challenging as skin or muscle biopsy findings can be non-specific and the characteristic rash is quite heterogeneous in presentation. For example, DM skin lesions often have a distribution similar to that of psoriasis and both diseases share activation of some common inflammatory pathways. In some cases, psoriatic lesions have been reported to occur in patients with DM, although it remains unclear if these lesions represent a coincidental occurrence of psoriasis and DM in the same patient or instead represent an atypical cutaneous manifestation of DM (1,2).
Objectives This clinical scenario was used to conduct the current proof-of-concept study to determine if molecular profiling could be used to aid the clinical diagnosis of DM in a patient in which traditional histopathology yielded inconclusive results.
Methods A tissue sample was obtained from a clinical and histopathologic psoriatic-appearing lesion occurring in a patient with known DM. Using oligonucleotide microarrays, its molecular features were compared to lesional skin biopsies obtained from 34 confirmed DM and 33 psoriasis patients.
Results We first identified the pathways enriched by differential transcripts which differentiate psoriasis from DM. We then demonstrated that the psoriasiform lesion displayed molecular features more similar to DM than psoriasis using both unsupervised hierarchical clustering and principal components analysis.
Conclusions This case study suggests that lesions that appear clinically and histologically similar to psoriasis may instead represent an atypical manifestation of DM. Furthermore, this also highlights the clinical utility of molecular profiling in enhancing diagnosis in autoimmune skin diseases.
Pavlovic, M Zecevic RD, Zolotarevski L. Psoriasis in a patient with dermatomyositis. Vojnosanit Pregl 2004; 61(5):557-9.
Kim NN, Lio PA, Morgan GA, Jarvis JN, Pachman LM. Double Trouble: Therapeutic Challenges in Patients With Both Juvenile Dermatomyositis and Psoriasis. Arch Dermatol 2011.
Disclosure of Interest K. Sarin: None Declared, L. Chung: None Declared, J. Kim: None Declared, B. Higgs Shareholder of: Astra Zeneca, Employee of: MedImmune, B. Jallal Shareholder of: Astra Zeneca, Employee of: MedImmune, Y. Yao Shareholder of: Astra Zeneca, Employee of: MedImmune, D. Fiorentino: None Declared