ABD - American Board of Dermatology Dermatologic Surgery Questions and Answers 1 — Questions and Answers
Question 1: A 68-year-old male with a history of a renal transplant presents with a 2.5 cm, poorly demarcated, recurrent basal cell carcinoma on his left temple. The biopsy shows an infiltrative growth pattern. According to the Appropriate Use Criteria, which of the following is the most appropriate next step in management?
- Excisional surgery with 5-mm margins
- Radiation therapy
- Mohs micrographic surgery (Correct answer)
- Topical imiquimod
Correct answer: Mohs micrographic surgery
Mohs micrographic surgery is the standard of care for high-risk basal cell carcinomas. This patient has multiple high-risk features including a large size (>1 cm on the face), location in a high-risk anatomic area (temple), recurrent tumor, immunosuppression, and an aggressive histologic subtype (infiltrative). Mohs surgery offers the highest cure rate while maximizing tissue conservation, which is critical in this cosmetically sensitive area.
Question 2: A surgeon is planning to repair a 3 cm circular defect on the cheek of a 55-year-old patient following Mohs surgery. To achieve the best cosmetic outcome with minimal tension, which of the following local flaps is most suitable for this type of defect?
- A rotation flap (Correct answer)
- A V-Y advancement flap
- A Z-plasty
- An island pedicle flap
Correct answer: A rotation flap
A rotation flap is ideal for closing circular or triangular defects. It is designed by incising a curvilinear line from the edge of the defect, allowing a semicircular flap of tissue to pivot or 'rotate' into the defect. This technique is particularly effective on the cheek where there is sufficient skin laxity to allow for movement with good cosmetic results.
Question 3: Which of the following laser-tissue interactions is the primary mechanism for the selective destruction of a target chromophore, such as melanin in a pigmented lesion, while minimizing damage to the surrounding tissue?
- Photochemical ablation
- Photodisruption
- Photoacoustic effect
- Selective photothermolysis (Correct answer)
Correct answer: Selective photothermolysis
Selective photothermolysis is the principle that allows for the specific targeting of a chromophore (e.g., melanin, hemoglobin). It requires using a wavelength of light that is preferentially absorbed by the target chromophore and a pulse duration that is shorter than the thermal relaxation time of that target. This confines the thermal energy to the target, causing its destruction with minimal collateral damage to surrounding structures.
Question 4: A 45-year-old patient undergoes cryosurgery with liquid nitrogen for a large, thick seborrheic keratosis on the back. Which of the following is the most common potential complication the patient should be counseled about?
- Atrophic scarring
- Dyspigmentation (Correct answer)
- Secondary bacterial infection
- Nerve damage
Correct answer: Dyspigmentation
Dyspigmentation, particularly hypopigmentation, is the most common complication following cryosurgery. This occurs because melanocytes are very sensitive to cold injury and can be easily destroyed by the freezing process. While other complications like scarring, infection, and nerve damage can occur, they are less frequent than pigmentary changes.
Question 5: When repairing a large surgical defect, what is the primary advantage of using a local flap reconstruction compared to a full-thickness skin graft?
- It involves a less complex surgical procedure.
- The donor site can be closed by primary intention.
- It maintains its own intrinsic blood supply. (Correct answer)
- There is a lower risk of postoperative infection.
Correct answer: It maintains its own intrinsic blood supply.
The fundamental difference between a flap and a graft is the blood supply. A flap is tissue that is moved from a donor site to a recipient site while maintaining its own vascular pedicle, or blood supply. In contrast, a skin graft is completely detached from its blood supply and relies on the recipient bed for revascularization. This intrinsic blood supply makes flaps more robust and generally leads to better cosmetic outcomes.
Question 6: A patient with a history of scleroderma develops a squamous cell carcinoma on the forearm. During Mohs surgery, the surgeon encounters significant difficulty in achieving clear margins due to the infiltrative nature of the tumor into the fibrotic dermis. This scenario highlights a limitation of Mohs surgery in which of the following situations?
- Tumors located on the trunk and extremities
- Tumors with perineural invasion
- Tumors arising in previously radiated skin
- Tumors with aggressive growth into deep structures (Correct answer)
Correct answer: Tumors with aggressive growth into deep structures
A limitation of Mohs surgery is that it can be difficult for the surgeon to achieve clear margins in tumors that have an aggressive growth pattern invading into deeper structures such as bone, cartilage, or, in this case, the dense, fibrotic tissue associated with scleroderma. The altered tissue characteristics can make it challenging to process and interpret the frozen sections accurately.
ABD - American Board of Dermatology Dermatologic Surgery Questions and Answers 1
A 68-year-old male with a history of a renal transplant presents with a 2.5 cm, poorly demarcated, recurrent basal cell carcinoma on his left temple.
The biopsy shows an infiltrative growth pattern.
According to the Appropriate Use Criteria, which of the following is the most appropriate next step in management?