Steatocystoma multiplex is an uncommon disorder that's characterized by multiple soft, movable, small, cystic nodules. The diameter of lesions typically varies from 0.2~2 cm, but the nodules may be larger. The overlying epidermis is usually normal with no central punctum present. The lesions are typically located on the upper trunk, neck, axillae, scrotum and proximal extremities2
. There may also be cases where there are scattered lesions on the scalp or face; however, it is very rare that the lesions are limited to the scalp ()3,4,7-12
Summary of the reported cases of steatocystoma multiplex limited to the scalp
The pathogenesis of these lesions has been extensively studied. Steatocystomas were initially thought to be sebaceous or retention cysts13
. In 1964, Kligman and Kirschbaum14
included these as a variant of dermoid cysts because of the presence of both hair shafts and sebaceous lobules. Steatocystomas are now recognized as a nevoid or hamartomatous malformation of the pilosebaceous junction1
Steatocystoma multiplex is usually hereditary and it is inheirited as an autosomal dominant trait. However, it is nonhereditary for cases that the lesions are mainly limited to the scalp. The differences between typical steatocystoma multiplex and that limited to the scalp are presented in . In 1996, Lee et al6
reported on a case of sebocystomatosis that displayed multiple lesions of steatocystoma multiplex confined only to the forehead and frontal scalp together with congenital alopecia, and this was considered as a clinical variant of steatocystoma multiplex. Steatocystoma simplex, which is rarely found on the scalp, was first described as a distinct entity by Brownstein15
in 1982. It is similar to our case for the pathogenesis, the genetic propensity and the prognosis; however, steatocystoma simplex has a solitary nature ()15-18
. Lim et al12
presented a patient with eruptive steatocystoma multiplex on the scalp. It was different from our case in that the lesions had appeared abruptly within a short period of time and the cysts showed an ovoid dilated cyst wall on histological study. Our case is educationally unique for the following points: (1) the presence of several cysts limited to the scalp, (2) no family history of similar lesions, (3) a late onset for the condition and (4) no congenital alopecia.
Differences among typical steatocystoma multiplex, steatocystoma multiplex limited to the scalp and steatocystoma simplex
The causative factors of steatocystoma multiplex remain unclear, yet Setoyama et al11
suggested that trauma, infection or immunological events might be responsible. Some authors have reported that steatocystoma multiplex has been associated with ichthyosis and koilonychia, pachyonychia congenita, acrokeratosis verruciformis of Hopf, hypertrophic lichen planus, hypohidrosis, hypothyroidism, hidradenitis suppurativa and hypotrichosis4,18,19
. For steatocystoma multiplex limited to the scalp, there have been no reports about specific causative factors and the relationship with other disorder, as was the case for our patient3,4,7-12
The clinical differential diagnosis of steatocystoma multiplex includes multiple epidermoid cysts, eruptive vellus hair cyst, neurofibromatosis, lipomas and xanthomatosis. A skin biopsy specimen from a representative lesion is diagnostic. The characteristic histopathologic finding of the disease is the presence of flattened sebaceous lobules close to the cystic wall. The wall is composed of stratified, squamous epithelium without a granular layer. There are acellular eosinophilic cuticles on the luminal side of the cyst wall and keratin, oil or hairs in the lumen2
Treatment of steatocystoma multiplex is largely symptomatic. Removal of these lesions can be successfully achieved with simple excision or drainage of the cyst materials. Inflamed lesions have been reported to respond to intralesional steroid injections, carbon dioxide laser, oral retinoids or cryotherapy2
. The lesions are typically asymptomatic, but they are often cosmetically disconcerting. Our patient declined further treatment after the diagnosis was made.
We report here on a rare case of steatocystoma multiplex that sporadically developed in an elderly woman and the condition was limited to the scalp.