Acral subcutaneous steatocystoma multiplex: a distinct subtype of the disease?

Steatocystoma multiplex (SM) is a hamartomatous malformation of the pilosebaceous duct consisting of dermal cysts filled with a sebum-like material. SM lesions are typically located in areas with sebaceous follicles, although atypical presentations involving sites lacking sebaceous follicles have exceptionally been described. We reviewed retrospectively a series of 32 histologically diagnosed SM observed in our department in the period 2006-2010, evaluating the kinds of lesions and their locations, and family history of SM and associated disorders, to focus on the clinical features of the acral subcutaneous variety of SM and to estimate its prevalence. We found five patients (four women and one man) with asymptomatic deep, skin-colored nodules on the flexor surfaces of distal upper extremities with a mean age at diagnosis and at disease onset of 32.5 and 26 years, respectively. The prevalence was 15%. All five cases were sporadic. The male patient had eruptive syringomas as an associated condition, together with a family history of this tumour. Acral subcutaneous SM may represent a distinct disease variety by virtue of its distinctive clinical features. Dermatologists should be aware of this form, which has to be included in the wide panel of diseases involving subcutaneous tissue.