The objective of this study is to determine the efficacy, safety, tolerability, and patient satisfaction associated with the treatment of epidermoid cysts with injected 1.5% sodium tetradecyl sulfate (STS) foam.

The primary objective is to determine the efficacy of STS foam injection on EIC with an endpoint of clinical resolution and cyst wall destruction on histology.

Enrolled subjects will undergo aspiration of cyst contents through an 18g needle immediately followed by injection of 1.5% STS foam (until the cyst is full and foam is flowing out of the injection site) followed by surgical excision 60 days later. The foam will be created by diluting 3% STS with an equal volume of normal saline then mixing with air in a 1:4 ratio using a female-to-female coupler.

Inclusion Criteria:

• Adults in good general health based on the investigator's judgment and medical history aged 18-80 years old

• Must be willing to sign a photography release and ICF.

• Subject must be willing to undergo study procedures, including STS foam injection and excision with simple closure with an expected linear scar.

• Epidermal inclusion cyst on the skin (not on mucosa or genitals) at least 4 mm in size

• Negative urine pregnancy test at the time of study entry (if applicable)

• Females will be either of non-childbearing potential defined as:

  1. Having no uterus
  2. No menses for at least 12 months. Or; Female subjects of childbearing potential must agree to use an effective method of birth control during the course of the study. All systemic birth control measures must be in consistent use for at least 30 days prior to study enrollment participation. Acceptable forms of birth control are below:
  1. Oral contraceptive pill, injection, implant, patch, vaginal ring, intrauterine device
  2. Intrauterine coil
  3. Bilateral tubal ligation
  4. Hysterectomy
  5. Barrier method used with an additional form of contraception (e.g., sponge, spermicide, or condom)
  6. Abstinence (If practicing abstinence, must agree to use a barrier method described above (4) If they become sexually active).
  7. Vasectomized (must agree to use barrier method described above (4) if they become sexually active with an un-vasectomized partner).

Exclusion Criteria:

• Pregnancy or planned pregnancy during the study or currently breastfeeding.
• Previously excised cysts or actively inflamed cysts will not be included in the study.
• Presence of incompletely healed wound in the treatment area.
• Any UNCONTROLLED systemic disease -a potential patient in whom therapy for a systemic disease is not yet stabilized will not be considered for entry into the study.
• Significant history or current evidence of a medical, psychological, or other disorder that, in the investigator's opinion, would preclude enrollment into the study.
• Allergy to STS.
• Active dermatitis, active bacterial, neurologic, fungal, or viral infection in the proposed treatment area.
• Inability to ambulate following the procedure.
• Current participation or participation within 30 days prior to the start of this study in a drug or other investigational research study.