Smooth Muscle Hamartoma Mimicking Multiple Eccrine Hidrocystomas

Abstract

of multiple eccrine hidrocystomas was made and a biopsy was performed for confirmation. The biopsy revealed a smooth muscle hamartoma compressing the eccrine glands, thereby causing cystic ectasia of both the secretory coils and the eccrine ducts. Immunostaining with anti-actin antibodies and Massontrichrome stain was positive in muscle fibers (Figure 2). Treatment was initiated with antiperspirant drugs (aluminum chlorohydrate, 20%) and produced a slight improvement; the patient’s symptoms have since remained stable with no new lesions or growth of the existing lesions. Although the pathogenesis of eccrine hidrocystoma is not well understood, some authors consider that the lesion is due to retained sweat resulting from obstruction of the eccrine duct. 5-7 This is therefore true cystic ectasia of the dermal part of the eccrine duct. In our case, histology revealed a smooth muscle hamartoma that was compressing the excretory ducts of the eccrine sweat glands, thereby causing cystic dilation of the ducts and giving rise to lesions clinically suggestive of multiple eccrine hidrocystomas. This case supports the hypothesis that hidrocystoma is not a true tumor but the result of the obstruction of the excretory part of the sweat gland; it would also explain why the lesions were unilateral in our patient—unlike previously published cases. Treatment of solitary or Smith-type forms will essentially consist of surgical removal of the lesions. In multiple or Robinson-type forms, however, surgical treatment is not appropriate; several other therapeutic options have therefore been tried, with varying results. Patients should firstly be advised to avoid situations that trigger worsening of the lesions, such as exercise and very hot environments. Oral atropine has also been used, but the systemic side effects outweigh the benefits. However, topical To the Editor: Eccrine hidrocystomas are rare cystic ductal lesions of the eccrine sweat gland. They were described by Robinson 1 in 1983 as multiple lesions that appeared on the face of women who worked in hot and humid environments. In 1973, Smith and Chernosky 2 described another group of patients in whom the lesion presented singly or in small numbers. Since then, these forms of presentation have become known as the classic or Robinson type and the solitary or Smith type, respectively. They present clinically as transparent or slightly blueish vesicular papular lesions measuring between 2 and 4 mm, on the face and torso. The lesions typically improve in winter and worsen in summer when they are exacerbated by sweatproducing stimuli, such as exercise and a warm humid environment; they may also be exacerbated by hormonal abnormalities such as hyperthyroidism. 3 Smooth muscle hamartoma is a benign process characterized by a proliferation of bundles of smooth muscle in the dermis. Almost all cases are congenital but acquired cases, such ours, also exist. These acquired forms are extremely rare and very few cases have been reported in the literature; to date, we have found only 1 published case of lesions on the face. 4