ABPath Dermatopathology 2 â Questions and Answers
Question 1: Which vasculitis is most strongly associated with c-ANCA (PR3-ANCA) and shows necrotizing granulomatous inflammation of small vessels?
- Henoch-Schönlein purpura
- Granulomatosis with polyangiitis (Wegener) (Correct answer)
- Polyarteritis nodosa
- Urticarial vasculitis
Correct answer: Granulomatosis with polyangiitis (Wegener)
Granulomatosis with polyangiitis (formerly Wegener's) is a small-vessel vasculitis strongly associated with c-ANCA/PR3-ANCA and shows necrotizing granulomatous inflammation affecting the upper airway, lungs, and kidneys.
Question 2: A skin biopsy shows a perivascular lymphoplasmacytic infiltrate and spirochetes on Warthin-Starry stain. This is most consistent with:
- Secondary syphilis (Correct answer)
- Erythema migrans (Lyme disease)
- Tinea corporis
- Granuloma annulare
Correct answer: Secondary syphilis
Secondary syphilis shows lichenoid or superficial/deep perivascular infiltrate with prominent plasma cells; Treponema pallidum spirochetes can be demonstrated with Warthin-Starry or immunohistochemical stains.
Question 3: Which syndrome links multiple sebaceous adenomas/carcinomas to internal malignancies (especially colorectal cancer) through mismatch repair gene mutations?
- Gardner syndrome
- Muir-Torre syndrome (Correct answer)
- Birt-Hogg-Dubé syndrome
- Cowden syndrome
Correct answer: Muir-Torre syndrome
Muir-Torre syndrome is a variant of Lynch syndrome caused by mismatch repair gene mutations (MLH1, MSH2), characterized by sebaceous neoplasms and an increased risk of visceral malignancies.
Question 4: Concentric 'onion skin' periductal fibrosis around eccrine sweat glands on skin biopsy is most characteristic of:
- Syringoma
- Morphea (localized scleroderma)
- Lichen sclerosus
- Systemic sclerosis (scleroderma) (Correct answer)
Correct answer: Systemic sclerosis (scleroderma)
Systemic sclerosis (scleroderma) characteristically shows concentric periductal fibrosis around eccrine glands and replacement of deep dermis/subcutaneous fat with densely packed collagen.
Question 5: A biopsy shows suprabasilar acantholysis with basal cells remaining attached to the basement membrane ('tombstoning'). This pattern is diagnostic of:
- Bullous pemphigoid
- Dermatitis herpetiformis
- Pemphigus vulgaris (Correct answer)
- Epidermolysis bullosa simplex
Correct answer: Pemphigus vulgaris
Pemphigus vulgaris shows suprabasilar acantholysis with 'tombstoning' of single basal cells still attached to the basement membrane, forming intraepidermal blisters due to anti-desmoglein 3 autoantibodies.
Question 6: Direct immunofluorescence (DIF) in dermatitis herpetiformis characteristically shows:
- Linear IgG along the basement membrane zone
- Granular IgA deposits in the dermal papillae (Correct answer)
- Intercellular IgG in a fish-net pattern
- IgM deposits around superficial blood vessels
Correct answer: Granular IgA deposits in the dermal papillae
Dermatitis herpetiformis shows granular IgA deposits in the tips of the dermal papillae on DIF, reflecting tissue transglutaminase autoantibody deposition in this gluten-sensitive dermatosis.
Question 7: Peripheral palisading of basaloid nuclei and retraction artifact (clefting) between tumor nests and stroma are hallmarks of:
- Trichoepithelioma
- Pilomatricoma
- Basal cell carcinoma (Correct answer)
- Syringoma
Correct answer: Basal cell carcinoma
Peripheral nuclear palisading and stromal retraction artifact (clefting) between tumor nests and the surrounding stroma are defining histological features of basal cell carcinoma.
ABPath Dermatopathology 2
Which vasculitis is most strongly associated with c-ANCA (PR3-ANCA) and shows necrotizing granulomatous inflammation of small vessels?