"Purple Toes": an Uncommon Sequela of Oral Coumarin Drug Therapy

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Abstract
Cutaneous vascular lesions following anticoagulant therapy with coumarin derivatives occurring in 6 patients are described and case details are presented. The lesions consist of a dark blue-tinged bilateral purple discoloration of the feet, especially the plantar surfaces and the sides of the first two toes. This was sometimes preceded or accompanied by a red-tinged violaceous nondescript discoloration of the thenar and hypothenar eminences of the hands. These lesions have the following in common 1) they develop 3-8 weeks after the patient is started on treatment with either Dicumarol or warfarin; 2) at the time the lesions appear, the prothrombin times (1 stage Quick method) are all in the therapeutic range, i.e. 1.75-2.5 times the control time and there is no clinical or laboratory evidence of epistaxis, hematuria blood in the stools, hemoptysis or other type of hemorrhage; 3) the color blanches completely on moderate pressure, 4) the color fades but never disappears on elevating the legs 90[degree] from the horizontal; 5) the toes are both symptomatically painful and tender on palpation; 6) the intensity of the discoloration and tenderness may wax and wane but the color changes persist indefinitely. Biopsy specimens obtained from the skin in an involved area in 4 of the 6 patients did not add any significant information. The lesions entitled "purple toes" are differentiated from other dermatological effects which have been observed in the course of anticoagulant therapy and possible mechanisms for their production are suggested.