Mixed Deck — All ABD Topics Flashcards

According to the American Joint Committee on Cancer (AJCC) 8th edition staging system for melanoma, which of the following findings defines a primary tumor as stage T1b?

Answer: A melanoma <0.8 mm in thickness with ulceration

The AJCC 8th edition revised the T1 criteria. A T1a melanoma is defined as being <0.8 mm thick without ulceration. A T1b melanoma is defined as either being <0.8 mm thick with ulceration OR being 0.8-1.0 mm thick, with or without ulceration. Mitotic rate is no longer used for T1 sub-categorization.

A cutaneous tumor shows peripheral palisading of basaloid cells with clefting (retraction) from the surrounding stroma. What is the diagnosis?

Answer: Basal cell carcinoma

Peripheral palisading of basaloid nests with stromal retraction artifact is characteristic of basal cell carcinoma.

Perioral and acral mucocutaneous lentigines in Peutz-Jeghers syndrome result from germline mutations in which gene?

Answer: STK11/LKB1 (serine-threonine kinase 11) on chromosome 19p

Peutz-Jeghers syndrome is caused by autosomal dominant germline mutations in STK11 (LKB1), encoding a serine-threonine kinase tumor suppressor on chromosome 19p13, leading to mucocutaneous lentigines and hamartomatous gastrointestinal polyps.

Why is it important to read peer-reviewed dermatology journals?

Answer: They offer evidence-based clinical updates.

Peer-reviewed dermatology journals are critical resources for dermatologists because they publish research findings, clinical trials, and reviews that have been rigorously evaluated by experts in the field. This ensures that the information is evidence-based, allowing practitioners to stay current with the latest advancements, best practices, and treatment guidelines, ultimately improving patient care.

Langerhans cells in the epidermis are best characterized by the presence of which cytoplasmic organelle?

Answer: Birbeck granule

Birbeck (tennis-racket) granules are the ultrastructural hallmark of Langerhans cells.

A 5-year-old child presents with a history of generalized blistering since birth, particularly over trauma-prone areas. The blisters heal with significant atrophic scarring, milia formation, and have resulted in mitten-like deformities of the hands (pseudosyndactyly). A mutation in the gene encoding which of the following structural proteins is responsible for this condition?

Answer: Type VII collagen

The clinical presentation of severe blistering with significant scarring, milia, and pseudosyndactyly is classic for severe recessive dystrophic epidermolysis bullosa (RDEB). This condition is caused by mutations in the COL7A1 gene, which encodes type VII collagen. Type VII collagen is the primary component of anchoring fibrils, which secure the basement membrane to the underlying dermis. Its absence or dysfunction leads to a cleavage plane in the sublamina densa, resulting in the deep, scarring blisters characteristic of DEB. Mutations in keratin 5 or 14 cause EB simplex, laminin 332 mutations cause junctional EB, and plectin mutations cause EB simplex with muscular dystrophy.

A child has multiple dome-shaped umbilicated papules on the trunk. What is the causative agent?

Answer: Poxvirus

Molluscum contagiosum is caused by a poxvirus and produces umbilicated papules.

The most common metal allergen causing allergic contact dermatitis, often from earrings and belt buckles, is what?

Answer: Nickel

Nickel is the leading contact allergen worldwide, frequently from jewelry, fasteners, and buckles.

UVA radiation (320-400nm) primarily penetrates to which level of the skin?

Answer: Dermis

UVA radiation penetrates deeply into the dermis, reaching dermal fibroblasts and blood vessels, and is the primary driver of photoaging and tanning through oxidative mechanisms.

The dermis derives its tensile strength predominantly from which structural protein?

Answer: Type I collagen

Type I collagen is the most abundant dermal protein providing tensile strength.

Which immune checkpoint inhibitor targeting PD-1 is used in advanced melanoma?

Answer: Nivolumab

Nivolumab is an anti-PD-1 monoclonal antibody used to treat advanced melanoma.

Nicotinamide (vitamin B3) supplementation has been shown to do what in high-risk patients?

Answer: Reduce the rate of new keratinocyte carcinomas and actinic keratoses

Oral nicotinamide reduces incidence of new nonmelanoma skin cancers and actinic keratoses in high-risk patients.

Which is the correct standard for supervising a physician assistant performing skin exams?

Answer: Supervision consistent with state law and scope of practice

PA supervision must follow state law and defined scope of practice.

A 66-year-old male with dermatitis herpetiformis is started on dapsone. Before initiating therapy, which laboratory test is mandatory to prevent a severe, dose-related adverse reaction?

Answer: Glucose-6-phosphate dehydrogenase (G6PD) level

Dapsone can induce oxidative stress on red blood cells, leading to hemolysis. Patients with a G6PD deficiency have a reduced ability to protect their red blood cells from this oxidative damage, placing them at high risk for severe, dose-dependent hemolytic anemia upon starting dapsone. Therefore, screening for G6PD deficiency is required before initiating therapy.

UV-triggered lupus erythematosus flares are mediated through which mechanism?

Answer: UVB and UVA-induced keratinocyte apoptosis exposing nuclear antigens

Both UVB and UVA trigger lupus flares by inducing keratinocyte apoptosis, which translocates nuclear antigens (Ro/SSA, La/SSB) to the cell surface, amplifying autoimmune responses.

Which UV wavelength range is primarily responsible for direct DNA damage forming cyclobutane pyrimidine dimers?

Answer: UVB (290-320 nm)

UVB is directly absorbed by DNA, generating cyclobutane pyrimidine dimers.

Neurofibromatosis type 1 is caused by a mutation in which gene?

Answer: NF1 (neurofibromin)

NF1 results from loss-of-function mutations in the NF1 gene encoding neurofibromin, a RAS-GTPase-activating protein.

Which is the best example of shared decision-making in dermatology?

Answer: Discussing options and preferences to reach a mutual treatment plan

Shared decision-making integrates clinical evidence with patient values and preferences.

Which dermatophyte finding on KOH prep confirms a diagnosis of tinea?

Answer: Septate branching hyphae

Dermatophyte infections show septate, branching hyphae on KOH microscopy.

The BRAF V600E mutation, targetable by vemurafenib/dabrafenib, is found in approximately what fraction of cutaneous melanomas?

Answer: About 40-50%

Roughly 40-50% of cutaneous melanomas harbor an activating BRAF mutation, most commonly V600E.