Muscle histopathologic findings in hypomyopathic dermatomyositis (HDM) have not been adequately characterized. We sought to determine the results of conventional and immunohistopathology in HDM. Light microscopic and immunohistochemical analysis was performed on muscle from 5 patients with HDM without muscle weakness. Ages ranged from 49 to 56 years. Creatine kinase level was normal. Electromyography showed mild "myopathic" changes in 2. The median duration of skin disease before biopsy was 18 months. Abnormal major histocompatibility (MHC) class I immunoreactivity was noted in myofibers in all specimens even when conventional histopathology was normal (1 patient) or only mildly abnormal (3 patients). One specimen had the characteristic findings of dermatomyositis. Patchy MHC-1 expression on myofibers was a consistent finding in HDM in the absence of other histopathologic abnormalities. The presence of MHC-1 expression could indicate a degree of endoplasmic reticulum stress even in the absence of clinical muscle weakness, muscle enzyme abnormalities, or significant inflammatory infiltrate.

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Cold-induced sweating syndrome (CISS) is a rare autosomal recessive disease due to mutation in the Cytokine receptor-like factor 1 (CRLF1). The characteristic symptom of CISS is the tendency to sweat profusely especially in the upper body and hands when the patient is exposed to cold temperature. We sought to first report the findings of autonomic reflex screen in a case of CISS type 1 with Cytokine receptor-like factor 1 mutation. Valsalva morphology, Valsalva ratio, and heart rate response to deep breathing were normal for the patient's age. Quantitative sudomotor axon reflex test showed nonlength dependent decrease in the sweat volume. Tilt table revealed evidence of reflex (vasovagal) "syncope," however, the patient was asymptomatic without loss of consciousness.

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