PA25 Persistent and widespread infantile transient smooth muscle contraction of the skin: an atypical presentation of a rare condition.

Abstract

Abstract Infantile transient smooth muscle contraction of the skin is a rare entity. Eleven cases have been described in the literature to date. Herein, we describe an unusual presentation, persistent and widespread in nature. A 2-year-old girl presented with asymptomatic bilateral transient textural change of the skin overlying the thighs. Textural changes were noted from birth, occurring a number of times each day. Episodes resolved spontaneously, sometimes within minutes, on occasion lasting up to 1 h. The child remained systemically well during episodes. Textural change progressed to involve the skin overlying the abdomen. Friction and temperature change did not provoke episodes. No other triggers were elicited. Background history included metatarsus adductus, which was under routine follow-up with orthopaedics. Full skin examination between episodes revealed no cutaneous abnormality. The areas affected were normal to palpate. Photographs and videos of episodes revealed marked textural change of the skin overlying both thighs and abdomen, with a striking stippled appearance. Laboratory investigations, including tryptase, lactate dehydrogenase, immunoglobulins and complement, were unremarkable. A case series first described nine cases of infantile transient smooth muscle contraction in 2013 (Torrelo A, Moreno S, Castro C et al. Infantile transient smooth muscle contraction of the skin. J Am Acad Dermatol 2013; 69:498–500). Textural skin changes occurred most frequently on the lower limbs. In eight of these cases, episodes resolved within 1 min. Episodes occurred both spontaneously and secondary to light friction from clothing, cool air and bathing. The majority of cases were noted from birth or in the first days of life. Skin biopsies taken from three of these patients revealed no abnormality. Episodes resolved by 2 years of age in all cases. It has been suggested that this transient phenomenon may be secondary to autonomic nervous system immaturity, primitive reflex phenomena or transient hypersensitivity of the smooth muscle. A more recent case has since been described in the literature (Theodosiou G, Belfrage E, Berggård K, Cristiansen J. Infantile transient smooth muscle contraction of the skin: a case report and literature review. Eur J Dermatol 2021; 31:260–1). We describe a persistent case of infantile transient smooth muscle contraction of the skin, in a child aged > 2 years, with prolonged episodes, progressing from lower limbs to truncal involvement. Recognition of this rare condition is important, to allow appropriate reassurance regarding its benign and self-limiting nature.