Idiopathic pure sudomotor failure responding to oral antihistamine with sweating activities.

Idiopathic pure sudomotor failure (IPSF) is characterised by diminished sweating with sudomotor stimuli, causes hyperthermia, dry skin, and itch or tingling of the skin surface, and severely impairs patients' quality of life. The treatment options for IPSF are limited. Systemic corti-costeroid has been used (1, 2), but it is not consistently effective (3). Here, we present 2 cases of patients with IPSF who responded to oral antihistamine treatment with sweating activity. CASE REPORTS Case 1. A 32-year-old male construction worker suffered from general fatigue accompanied by abnormal skin sensations, such as tingling sensation and itch after exposure to a warm environment at his work place that began in the spring. He was diagnosed with IPSF at another clinic on the basis of blood test results. Steroid pulse therapy (500 mg/day for 3 consecutive days) was given twice in one month, but did not provide a therapeutic benefit. Five months after the diagnosis of acquired idiopathic generalised anhidrosis (AIGA), the patient consulted our clinic. He had no history of cholinergic urticaria. At the first visit his body temperature was 37.0°C, and his blood levels of thyroid-stimulating hormone, free thyroxine, free triiodothyronine, immunoglobulin E, urinic acid, and HgbA1c were within normal limits. Anti-acetylcholine receptor antibody, anti-SSA antibody, and anti-SSB antibody were not detected in his serum. The result of the quantitative sudomotor axon reflex test (QSART), performed on the patient's forearm, was 0.025 mg/5 min [mean evaluation value from 26 healthy volunteers is 1.13 mg/5 min (range 0.495–4.54)], which is compatible with a diagnosis of anhidrosis. Sweat testing using minor methods (at 30ºC and 60% humidity) revealed anhidrosis on almost his entire body (Fig. 1a). Skin tissue samples were obtained from both lesional (anhidrosis) and non-lesional skin. Lymphocytic infiltration around the sweat gland and hyperkeratosis of the sweat pores were observed in both lesional and non-lesional areas (Fig. 1b, c). We assigned a diagnosis of IPSF in this case because there were no neurological signs. The first therapeutic strategy we tried, topical urea and steroid application, did not yield any improvement (Fig. S1 1). Next, to improve the subjective symptom of itch and tingling sensation of the skin, oral antihistamine (AH; fexofenadine) was administered at a normal dose (120 mg/day), which was gradually increased up to 3-fold the normal dose. A few days after initiation of the increased AH dose, the patient's subjective symptoms were improving (Fig. S1 1). We recommended the …