3,5 Based on the existing

literature, those with high risk features require a targeted assessment. Given the initial clinical presentation alone is an unreliable indicator of underlying autoimmune disease,5 investigations are required. There is little evidence on which to base the choice of investigation; however, Cetuximab two studies exploring the transition of “primary” perniosis and Raynaud’s phenomenon to “secondary” found ESR, ANA titer, rheumatoid factor, and serum protein electrophoresis to be the most useful markers.5,6 Abnormal results should raise the suspicion of a secondary cause and prompt a formal rheumatology consultation. Thumb-sparing perniosis is at present an undescribed clinical entity. However, thumb sparing has been noted in the context of Raynaud’s phenomenon. A retrospective study has shown a nonsignificant trend toward thumb sparing in primary Raynaud’s phenomenon.7 The author suggests that thumb involvement should prompt a search for an underlying

connective tissue disorder. Further study is required to discern whether perniosis shares a similar pathophysiological process and if thumb sparing may help predict primary disease. Prevention of perniosis is the most important arm of management. This should begin with a thorough screening history and examination. Primary prevention for those at risk includes protective extremity cover, layered warm clothing, VEGFR inhibitor avoidance of nicotine, and keeping skin dry to avoid heat loss.1,8 Other preventative measures include cessation GPX6 of smoking and avoiding vasoactive medications, if possible.

Pharmacotherapy is generally second-line management. Although limited in number, the available studies support nifedipine as the drug of choice. It is shown to decrease duration, severity, and recurrence of lesions.1,9 However, a recent Cochrane review failed to show any benefit of oral vasodilators in the treatment of primary Raynaud’s phenomenon.10 The idiopathic etiology of the current case is strengthened by the childhood history of a mild maladaptive peripheral vascular response to cold, male gender, thumb sparing, relief of symptoms in warmer climates, and unremarkable serology. This case reveals how a mild undiagnosed disease can manifest itself in extreme outdoor settings. In our case, the patient’s home country of Australia was likely of too temperate a climate to challenge the patient’s at-risk peripheries. It is such patients from warmer environments leaving for prolonged travel in cold temperatures that are at risk of having a presentation of undiagnosed perniosis while in an extreme setting. We have described a case of acute perniosis in a long-distance cyclist. This case demonstrates that patients about to embark on significant outdoor travel in cold environments should be screened with history and examination.