Postural rash

The photograph shows a postural rash on the lower limbs consisting of physiological anaemic macules (arrow A) (termed Bier anaemic spots), erythrocyanosis (arrow B) and urticaria-like lesions (arrow C). The condition, which has been called BASCULE syndrome (Bier anaemic spots, cyanosis and urticaria-like eruptions), is a benign vasomotor dermatosis.

The patient, a healthy girl of older primary school age, was referred to a dermatologist due to a pruritic postural rash present for six months. She had no accompanying orthostatic symptoms. Examination of the skin while she was lying down was unremarkable, but when she was in a standing position anaemic macules and pruritic orange-red blisters appeared on the lower limbs within a few minutes (see video). The rash faded spontaneously after a couple of minutes of lying down. Oral antihistamines twice daily were effective for the pruritus, but the rash continued to appear when she stood upright.

Symptoms and clinical findings were consistent with BASCULE syndrome. The condition, which was first described in 2016, most frequently affects the lower limbs of children and adolescents (1–3). The condition is also referred to as angiodyskinesia or gravitational erythema in the literature (4). There are fewer than 20 published cases.

The pathophysiology is not fully understood, but one theory is that the rash occurs due to an exaggerated response to venous stasis caused by orthostatism, in addition to a paradoxical urticarial reaction caused by local tissue hypoxia (1). There is no curative treatment, but oral antihistamines have been effective in relieving symptoms of pruritus in some patients (1, 3). The prognosis is good, with most cases resolving within months or a few years. The condition has been seen with concomitant postural tachycardia syndrome, and investigation with a tilt test has been recommended for patients with accompanying orthostatic symptoms (2, 3).

Many clinicians are not aware of this diagnosis, which can result in patients undergoing multiple unnecessary tests such as angiography, ultrasound scans, skin biopsy and extensive blood workup (1–4).