The design is a prospective, observational registry for subjects with CHE under the care of dermatology or other qualified healthcare provider. Longitudinal data are collected from both subjects and their treating provider during routine clinical encounters using a structured and standardized data collection method

The objective of the registry is to create a cohort of CHE subjects to evaluate long-term real world safety and effectiveness of standard of care treatments for CHE. Data collected through the registry may be used to address a range of research questions and use cases, including but not limited to: characterizing the natural history of the disease, evaluating the effectiveness and safety of commercially available medications for the treatment of CHE, providing information to support ongoing risk-benefit evaluation by drug manufacturers and regulators, and research related to drug utilization, disease burden, and unmet needs. Further, data collected will inform clinical decision making by patients and treating providers.

Inclusion Criteria:

• To be eligible to participate in this registry, an individual must meet all of the following criteria:

  1. Diagnosed with moderate-to-severe CHE by a dermatologist or other qualified healthcare provider at the time of enrollment and initiating an eligible medication.
  2. Is at least 18 years of age or older and has attained the legal age for consent to procedures involved in the research, under the applicable law of the jurisdiction in which the research is being conducted at the time of enrollment
  3. Is willing and able to consent to participation in the registry
  4. Is willing and able to complete registry-related forms electronically via personal devices.
  5. Is willing and able to provide the information (first name, last name, email address, language and primary time zone) required to create an account to allow you to complete registry forms via a personal device;
  6. Is willing and able to provide Personal Information (full legal name, sex, date of birth, home address zip or postal code and email address or phone number at a minimum) if required based on registry location and applicable laws and regulations.

Exclusion Criteria:

An individual who meets any of the following criteria will be excluded from participation in the registry:

1) Is participating or planning to participate in a blinded clinical trial for a CHE drug

Subjects enrolled in this registry will be treated according to routine clinical care; treatments are prescribed at the provider's discretion and the decision to treat the subject with a drug is made prior to and independently of study participation. The clinician will determine subject visit schedules according to routine practice, patient needs, and local standard of care (SoC)