INTRODUCTION: Harlequin phenomenon is characterized by a strictly unilateral 
erythrosis of the face with flushing and hyperhydrosis, and controlaterally a 
pale anhydrotic aspect. This syndrome can occur alone or associated to other 
dysautonomic phenomena such as Horner syndrome, Adie syndrome or Ross syndrome.
PATIENTS AND METHODS: We report three cases: two patients presented a Harlequin 
sign, associated with Horner syndrome for one and Ross syndrome for the second. 
The etiologic investigation was normal, allowing recognizing the idiopathic 
nature of the disorder. For the third patient, Harlequin syndrome was observed 
in a neoplastic context due to breast cancer, metastatic dissemination, and bone 
metastases involving the right side of the T2 body.
DISCUSSION: We reviewed the literature: 108 cases have been described. This 
syndrome occurred alone in 48 patients and was associated with other 
dysautonomic syndromes such as Horner syndrome in 38 patients, Holmes Adie 
syndrome in six, and Ross syndrome in six; both Ross and Holmes Adie syndrome 
were associated five cases and associations were not reported in five patients. 
The pathophysiological mechanisms of this autonomic cranial neuropathy, the 
possible etiologies, and therapeutic management were discussed.
CONCLUSION: Harlequin phenomenon with flushing and unilateral hyperhydrosis is 
rare, occurring alone or in combination with other autonomic syndromes of the 
face. Idiopathic in two-thirds of cases, Harlequin phenomenon does not require 
specific treatment; sympathectomy may be discussed in the severe cases with a 
significant social impact.