The CDT credential from The Association of Certified Dermatology Techs is for people who work as assistants alongside dermatologists. This page sets out the checked facts about the online program: the $199 fee, the 75% pass mark on module quizzes and the experience requirement. It also gives you free practice sets by topic, from biopsies and wound care to phototherapy, plus worked explanations of sample questions.

CDT Exam at a Glance

What the CDT is and how it works

According to The Association of Certified Dermatology Techs, “Each module has a corresponding quiz which must be passed with a score of 75% or higher in order to receive credit.”^[1]

The Certified Dermatology Tech (CDT) credential is run by The Association of Certified Dermatology Techs for people who assist dermatologists in clinical practice. It is a training and certification program, not an exam you sit at a test centre. The program is delivered entirely online and is self-paced, so you can do it anywhere you have an internet connection.

How it is scored. The coursework is 16 hours of modules. Each module ends with a quiz, and you need 75% or higher on each quiz to get credit. You can repeat a quiz until you pass, and you have up to 1 year from enrollment to finish.

Eligibility. Finishing the modules is not the last step. Before full certification is granted, your supervising physician is asked to confirm that you have at least 6 months of full-time experience (or 1,000 hours part-time) working as an assistant in dermatology.

Cost and renewal. Individual registration is $199, or $99 per person when 5 or more people enroll together. The credential is valid for 4 years. Recertification costs $39 and involves a nearly 300-question exam with a passing mark of 75.

Whether an employer or a state requires or recognises the CDT varies. Check with your employer, and confirm current fees and rules at dermatologytech.org before you enroll.

Worked examples: how to reason through CDT questions

These are practice questions written for this site, not questions from the real exam. Each explanation shows why the right answer is right and why the others are wrong.

Example 1

Question: Which fixative is the standard for preserving biopsy specimens before histopathologic analysis?

1. Normal saline
2. 70% ethanol
3. 10% neutral buffered formalin
4. Glutaraldehyde

Answer: C. 10% neutral buffered formalin

Explanation:

C is correct. 10% neutral buffered formalin is the standard fixative for routine biopsies. It cross-links proteins, which holds cells and tissue structure in place so the pathologist sees architecture close to how it was in the patient. It also works with routine stains such as H&E.

• Normal saline is not a fixative. Tissue left in it keeps breaking down, so it is only used briefly when the lab asks for it.
• 70% ethanol dehydrates tissue and can shrink or distort it. It is used for some cytology, not routine skin biopsies.
• Glutaraldehyde is kept for electron microscopy.

Rule: routine skin biopsies go into formalin unless the order says otherwise. For example, direct immunofluorescence specimens need a special transport medium. Always read the requisition before you pick the container.

Example 2

Question: Which dressing type creates a moist wound environment while being appropriate for a heavily exudating wound?

1. Hydrocolloid
2. Transparent film
3. Alginate
4. Hydrogel

Answer: C. Alginate

Explanation:

C is correct. Alginate dressings come from seaweed and absorb a lot of fluid. When they touch wound exudate they turn into a soft gel, which keeps the wound bed moist while drawing excess fluid away. They usually need a secondary dressing over them.

• Hydrocolloid is occlusive and suits light to moderate exudate. On a heavily draining wound it can leak and soften the surrounding skin.
• Transparent film absorbs almost nothing. It suits superficial wounds with minimal drainage, or holding other dressings in place.
• Hydrogel adds moisture, so it is meant for dry wounds. On a wet wound it makes things worse.

Rule: match the dressing's absorbency to the amount of exudate. Use absorbent dressings such as alginate or foam for wet wounds, and moisture-donating dressings such as hydrogel for dry ones.

Example 3

Question: A dermatology tech documents a lesion as 'annular.' This term means the lesion is:

1. Linear and streak-like
2. Ring-shaped with central clearing
3. Irregular with scalloped borders
4. Dome-shaped and smooth

Answer: B. Ring-shaped with central clearing

Explanation:

B is correct. Annular means ring-shaped, usually with a clearer centre and a more active edge. Tinea corporis and erythema migrans are classic examples, which is why the term matters for both diagnosis and documentation.

• Linear and streak-like is the term linear, seen for example with plant contact dermatitis or the Koebner phenomenon.
• Irregular with scalloped borders describes the border of a lesion, a feature watched for in pigmented lesions. It does not describe a ring pattern.
• Dome-shaped and smooth describes elevation and surface, as in a papule or nodule such as molluscum, not configuration.

Rule: keep the categories of lesion description separate. Configuration (annular, linear, grouped), border (regular, irregular) and elevation or surface (flat, dome-shaped, smooth) are different things, and a full note may need all of them.

How to use these practice tests

Start with the official module material from the Association, because only the module quizzes earn credit. Before each module, take the matching practice set here cold to see what you already know. For anatomy, try CDT Skin Anatomy & Physiology. For lesion description, use CDT Dermatological Assessment Methods. For specimens, use CDT Laboratory Procedures & Biopsies.

Then work through the module and retake the same set. Write down each question you missed along with the rule behind the right answer, as in the worked examples above. Rules carry over to new questions; remembered answer letters do not.

• Pair related sets: wound care with topical medication administration, and common skin conditions with dermatologic conditions and diseases.
• Save safety, ethics and infection control and patient education for near the end, because they apply to every topic.
• Try to reach 75% on our sets before you attempt a module quiz, but treat that only as a rough check. We wrote these questions ourselves; they are not taken from the real quizzes.

Keep a record of your supervised hours as you go, so your supervising physician can confirm your experience when you finish.

Sources & last verified

1. The Association of Certified Dermatology Techs — passing score, retake policy, validity, delivery (official source). “Each module has a corresponding quiz which must be passed with a score of 75% or higher in order to receive credit.” Verified Oct 21, 2026.
2. The Association of Certified Dermatology Techs — exam fee (official source). “Individual Registration $199” Verified Oct 21, 2026.
3. The Association of Certified Dermatology Techs — renewal (official source). “Individuals may CLICK HERE to purchase. The cost is just $39.” Verified Oct 21, 2026.

How we verify: editorial & fact-checking policy. Report an error: contact us.