Steatocystoma multiplex (SM) and eruptive vellus hair cysts (EVHC) are uncommon benign tumors of the pilosebaceous unit. SM is characterized by multiple smooth asymptomatic papules or nodules, usually presenting on the chest, limbs and axillae, back, or abdomen. Facial involvement is less frequently noted but has been reported [
A 15-year-old Caucasian male presented with a six-year history of multiple noninflamed, nonumbilicated papules on his anterior chest and abdomen. The initial eruption in 2009 of white and pink perifollicular 1-2 mm papules was especially numerous (>25) over the sternum, where they developed in a diamond-shaped pattern. No family history of similar dermatological disorders was noted. This eruption was clinically diagnosed as steatocystoma multiplex and showed significant improvement after five years of treatment with a topical 10% glycolic acid lotion. I&D expression of the few remaining lesions resulted in oily, curd-like material containing multiple vellus hairs (Figure
Vellus hairs present in cysts from clinical presentation case #1, a 15-year-old male patient. Cyst contents were expressed via incision and drainage and mounted with a coverslip without KOH. Scale bar = 100 microns.
Representative photomicrograph of a steatocystoma stained with hematoxylin and eosin (H&E) at 100x (a) and 400x (b) magnification. Abundant sebaceous input is clearly visible in the cyst wall.
A 67-year-old Caucasian female presented with numerous 1-2 mm white and yellow papules in a bilateral periorbital distribution (Figure
(a) Clinical presentation case #2, a 67-year-old female patient, presurgery. Numerous periorbital 1-2 mm white and yellow papules are shown. Papules inside the highlighted region (black box) were removed surgically. (b) Clinical presentation case #2, one year after surgery. No recurrence of removed papules was observed (boxed region).
Representative photomicrograph of EVHC stained with H&E at 100x (a) and 400x (b) magnification. Keratin and numerous vellus hair shafts are visible in the cyst lumen.
Many similarities exist between SM and EVHC in terms of clinical presentation. Both SM and EVHC are most likely to emerge during adolescence or early adulthood [
Most cases of SM and EVHC are sporadic, although familial cases of each have been reported and are transmitted in an autosomal dominant fashion [
The true differentiation between SM and EVHC occurs at the histological level. Histological examination of a biopsied SM cyst will reveal thin walls of stratified squamous epithelium without a granular layer, typically with abundant sebaceous input (Figure
EVHCs originate from the isthmus or infundibulum of the pilosebaceous unit and thus are often lined by squamous epithelium containing a granular layer, in contrast to SM. These cysts also typically contain laminated keratin and multiple vellus hairs (Figure
Intriguingly, there have been various reports of patients presenting with both SM and EVHC concurrently, or with hybrid cysts that exhibit features of both disorders [
Ultimately, the distinction between SM and EVHC may be primarily an academic one. Both lesions respond to similar treatment modalities and the problems they present are predominantly cosmetic, as they are rarely correlated to any serious genetic syndromes. Noted interventions with a history of efficacy include expression via surgical incision, excision, or needle aspiration; retinoic acid; and Erbium:YAG or CO2 lasers [
Our report details two cases of uncommon pilosebaceous tumors, steatocystoma multiplex, and eruptive vellus hair cysts. Despite clear histological differences between these lesions, SM and EVHC are similar in clinical presentation and management. “Hybrid-type” tumors present strong evidence for a relationship between the SM and EVHC pathologically. Due to their relative rarity of occurrence, familiarity with cyst presentation in these lesions will prove useful for accurate clinical diagnosis.
The authors declare no conflicts of interest regarding the publication of this paper.
The authors would like to thank Michael Rabkin, M.D., Ph.D., and Milena Kozovska, M.D., Ph.D. (both of the Rabkin Dermatopathology Laboratory in Tarentum, PA) for the photomicrograph images of representative SM and EVHC histology. The authors also gratefully acknowledge the University of Illinois-Chicago Research Open Access Article Publishing (ROAAP) Fund for financial support in publishing this case report.