Steatocystoma Multiplex

A number sign (#) is used with this entry because of evidence that steatocystoma multiplex is caused by heterozygous mutation in the keratin-17 gene (KRT17; 148069) on chromosome 17q21.

Mutation in the KRT17 gene has also been found as the cause of pachyonychia congenita-2 (PC2; 167210).

Also see steatocystoma multiplex with natal teeth (184510), which may be a separate disorder.

Clinical Features

In typical cases the patient may exhibit 100 to 2,000 round or oval cystic tumors widely distributed on the back, anterior trunk, arms, scrotum, and thighs. Noojin and Reynolds (1948) observed 12 cases in 3 generations.

Sebaceous cysts presenting mainly as wens of the scalp were reported by Stephens (1959) in a large number of individuals in 5 generations in a dominant pedigree pattern.

Bushkell and Gorlin (1975) found leukonychia totalis (151600), multiple sebaceous cysts, and renal calculi in grandfather, father and son, and some of these features in 2 other relatives. Koilonychia (149300) was also found in 3 of the affected persons.

Malignant degeneration of a cyst in a steatocystoma case was reported by Harper and Davis (1971).

Cuccia-Belvedere et al. (1989) studied steatocystoma multiplex in 13 persons in 2 unrelated Italian families.

Clinical Management

Pamoukian and Westreich (1997) described their experiences in the treatment of 7 members of a family of Jewish Turkish origin over a period of 17 years. Steatocystoma multiplex congenita, especially the cysts in exposed areas of the body, created serious self-image problems. Because of the number of cysts and their fragility, standard cyst excision techniques were impractical and difficult. They described a modified excision method that yielded good results. Their method consisted of making a stab incision into the cyst and manually evacuating its contents. Thereafter, a fine mosquito hemostat was inserted to grasp the cyst wall from within and strip out its lining. At one sitting, 50 to 150 cysts could be removed. Excisions were performed once or twice a year.

Molecular Genetics

Smith et al. (1997) described mutations in the KRT17 gene in 2 families diagnosed with steatocystoma multiplex. On reevaluation, mild changes in the nails were found in some but not all members of these 2 families, compatible with pachyonychia congenita, and some members had mild focal nonepidermolytic palmoplantar keratoderma. There was no history in either family of natal teeth. Smith et al. (1997) suggested that the disorder in these families was a variant of PC2.