Anti-PM/Scl and hypomyopathic dermatomyositis: a novel association

Case Report: We report the case of a 73 years old man, who referred to ourUnit for infiltrated erythematous skin lesions localised on the face, neck and proximal limbs. Routine blood tests demonstrated increased values of CPK, myoglobine and ALT. Search for autoantibodies revealed the presence of antinuclear antibodies (ANA 1:320 speckled) and anti-PM/Scl. The patient subsequently underwent further investigations for connective tissue disease, even if he didn’t complain for any other symptom at the time of consultation and physical examination, except for the above mentioned skin lesions, was unremarkable. Physical tests, electromiography and muscle NMR didn’t show any sign of muscle involvement. Arterial blood gas analysis, pulmonary function tests, including DLCO, and chest HRCT didn’t show any sign of interstitial lung disease. Renal function was normal with no proteinuria. We therefore performed skin biopsy which showed lichenoid tissue reaction consisting of vacuolization of basal layer cells and oedema of papillary dermis, associated with dilatation of superficial vessels and dermal infiltration predominantly consisting of lymphocytes and minimal numbers of neutrophils and eosinophils. Being these findings consistent with a diagnosis of dermatomyositis (DM), and excluding any muscle involvement, we concluded for a diagnosis of hypomyopatic DM. This clinical entity is a rare subset of dermatomyositis which is characterised by DM-specific skin disease and subclinical evidence of myositis on laboratory, electrophysyologic and/or radiologic evaluation. Anti-PM/Scl are autoantibodies which can be found in polymyositis/systemic sclerosis overlap syndromes. To date, no other cases of hypomyopathic dermatomyositis have been reported in association with anti-PM/Scl. The patient is currently being followed up as he may develop myositic and/or systemic sclerosis manifestations in the future.