Solitary lesions are known as steatocystoma simplex and usually affect adults. Steatocystoma multiplex, as in this patient, usually presents in adolescence and has an autosomal dominant inheritance. Lesions can be distributed generally, but are most often seen on the sternal chest in boys and in the axilla and groin in girls. Localized variants have been reported. Larger lesions can rupture and become suppurative (steatocystoma multiplex suppurativum), and leave scars upon resolution.[1,2]
Steatocystoma multiplex can be seen as part of the clinical manifestation of pachyonychia congenital type II (Jackson-Lawler syndrome). Pachyonychia congenital type I (Jasassohn-Lewandowsky syndrome) is characterized by thickened nail beds of the fingers and toes, palmar and plantar hyperkeratosis, follicular keratotic papules, and oral leukokeratosis. Pachyonychia congenital type II has the additional findings of steatocystoma multiplex, natal teeth and eruptive vellus hair cysts, and has less severe palmoplantar keratoderma and no oral leukokeratosis. Whereas pachyonychia congenital type I is the result of mutations in keratin 6a and 16, type II is the result of defects in keratin 6b and 17. Steatocystoma multiplex is caused by defects in keratin 10 and 17, explaining the presence of steatocystomas in pachyonychia congenital type II.
Histology
Steatocystoma multiplex has been described in association with eruptive vellus hair cysts. Some patients have both lesions simultaneously; others have lesions with overlapping histologic features. Histologically, steatocystomas are characterized by a cyst wall of squamous epithelium. The lesion lacks a granular layer but has a wrinkled eosinophilic cuticle with adjacent sebaceous glands. The cyst cavity is frequently empty but may contain sparse keratin or hair shafts. Conversely, vellus hair cysts are small cysts lined with squamous epithelium with granular cell layers, and contain many vellus hair shafts and lamellated keratin.
Treatment
No therapeutic modalities are universally effective in the treatment of steatocystoma. Isotretinoin can reduce the frequency of new lesions and reduce the severity of steatocystoma multiplex suppuritiva, but recurrence is common after cessation of treatment.[3] Cryotherapy has been reported to be successful, but is associated with a poor cosmetic outcome.[4] Numerous surgical techniques have been reported including CO2 laser ablation and perforation and extirpation of individual lesions.[5,6] At this time, our patient opted for no treatment