ABD - American Board of Dermatology Inflammatory Dermatoses Questions and Answers 1 — Questions and Answers
Question 1: A 42-year-old male with severe plaque psoriasis and psoriatic arthritis has failed topical therapies and phototherapy. He has a positive tuberculin skin test and chest X-ray findings consistent with latent tuberculosis. Initiation of which of the following biologic agents would carry the highest risk of tuberculosis reactivation, thus mandating pretreatment?
- Secukinumab
- Infliximab (Correct answer)
- Ustekinumab
- Brodalumab
Correct answer: Infliximab
Tumor necrosis factor-alpha (TNF-α) is critical for the formation and maintenance of granulomas that contain Mycobacterium tuberculosis. TNF-α inhibitors, such as infliximab, adalimumab, and etanercept, significantly increase the risk of reactivating latent tuberculosis by disrupting these granulomas. Therefore, screening and treatment for latent TB are mandatory before starting therapy with a TNF-α inhibitor. While other biologics carry some risk, it is most pronounced and well-established for the TNF-α inhibitor class.
Question 2: Loss-of-function mutations in the gene encoding which of the following proteins are the strongest known genetic risk factor for the development of atopic dermatitis?
- Keratin 14
- Loricrin
- Collagen VII
- Filaggrin (Correct answer)
Correct answer: Filaggrin
Filaggrin (filament aggregating protein) is a key structural protein essential for the formation and function of the stratum corneum. Loss-of-function mutations in the filaggrin gene (FLG) impair skin barrier function, leading to increased transepidermal water loss and enhanced penetration of allergens. This is the most significant and well-established genetic predisposition for atopic dermatitis.
Question 3: A biopsy from a pruritic, violaceous, polygonal papule on a patient's wrist is examined. Which constellation of histopathologic findings is most characteristic of lichen planus?
- Acantholysis, suprabasal split, and 'tombstoning' of basal cells.
- Hyperkeratosis, wedge-shaped hypergranulosis, sawtooth rete ridges, and a band-like lymphocytic infiltrate. (Correct answer)
- Spongiosis, eosinophilic infiltrate, and flame figures.
- Confluent parakeratosis, Munro's microabscesses, and suprapapillary plate thinning.
Correct answer: Hyperkeratosis, wedge-shaped hypergranulosis, sawtooth rete ridges, and a band-like lymphocytic infiltrate.
The classic histopathologic features of lichen planus include hyperkeratosis, wedge-shaped hypergranulosis, irregular acanthosis creating a 'sawtooth' appearance of the rete ridges, and a dense, band-like (lichenoid) lymphocytic infiltrate that obscures the dermo-epidermal junction. Apoptotic keratinocytes (Civatte bodies) are also commonly seen.
Question 4: A 23-year-old patient presents with an acute eruption. It began 10 days ago with a single 4 cm oval, salmon-colored plaque with a fine peripheral scale on her abdomen. This was followed by the development of numerous smaller, similar-appearing plaques oriented along cleavage lines on her back. What is the most likely diagnosis?
- Pityriasis rosea (Correct answer)
- Guttate psoriasis
- Secondary syphilis
- Nummular eczema
Correct answer: Pityriasis rosea
This is a classic clinical presentation of pityriasis rosea. The initial, larger lesion is known as the 'herald patch.' The subsequent eruption of smaller, oval plaques oriented along skin cleavage lines (Langer's lines) creates a characteristic 'Christmas tree' distribution on the back.
Question 5: A 65-year-old male develops widespread dusky macules, bullae, and severe mucosal erosions of the eyes and mouth 12 days after starting a new medication. A clinical assessment estimates epidermal detachment at 20% of the total body surface area. According to the consensus classification, what is the most accurate diagnosis?
- Erythema multiforme major
- Stevens-Johnson syndrome (SJS)
- Overlap SJS/Toxic epidermal necrolysis (TEN) (Correct answer)
- Toxic epidermal necrolysis (TEN)
Correct answer: Overlap SJS/Toxic epidermal necrolysis (TEN)
The classification of the SJS/TEN spectrum is based on the percentage of body surface area (BSA) with epidermal detachment. SJS is defined as <10% BSA detachment, TEN is >30% BSA detachment, and cases with 10-30% BSA detachment are classified as SJS/TEN overlap. With 20% involvement, this patient falls into the overlap category.
Question 6: Histopathologic examination of an asymptomatic, annular plaque on the dorsal foot reveals a palisaded granulomatous infiltrate in the mid-dermis. Which feature within the center of the palisades is most characteristic of granuloma annulare?
- Caseous necrosis
- Extensive fibrin deposition
- Prominent mucin deposition (Correct answer)
- Cholesterol clefts
Correct answer: Prominent mucin deposition
While several conditions can show palisaded granulomas, the hallmark of granuloma annulare is the presence of prominent mucin deposition within the central area of altered collagen (necrobiosis), surrounded by the palisaded histiocytes. This feature helps distinguish it from other granulomatous conditions like necrobiosis lipoidica or rheumatoid nodules.
ABD - American Board of Dermatology Inflammatory Dermatoses Questions and Answers 1
A 42-year-old male with severe plaque psoriasis and psoriatic arthritis has failed topical therapies and phototherapy.
He has a positive tuberculin skin test and chest X-ray findings consistent with latent tuberculosis.
Initiation of which of the following biologic agents would carry the highest risk of tuberculosis reactivation, thus mandating pretreatment?