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Zorluk: OrtaPathology and Biopsy Interpretation

A 74-year-old man comes to the clinic because of a severely pruritic rash that started two weeks ago. Over the past week, he has developed large, fluid-filled blisters on his lower abdomen, thighs, and forearms. Physical examination reveals multiple tense bullae on an erythematous and urticarial base. The Nikolsky sign is negative. Examination of the oral mucosa shows no erosions or ulcerations. A punch biopsy of the edge of an intact blister and a perilesional skin biopsy for direct immunofluorescence are performed to establish the diagnosis. Which of the following pathologic and immunofluorescence findings are characteristic of this patient's condition? (Select all that apply)

  1. Subepidermal blister formation with a prominent eosinophilic infiltrateCevap
  2. Linear deposition of IgG and C3 along the dermoepidermal junctionCevap
  3. C
    Intraepidermal cleavage with suprabasal acantholysis
  4. D
    Intercellular reticular pattern of IgG deposition within the epidermis
  5. E
    Granular deposition of IgA at the apices of dermal papillae

Cevap

The characteristic findings are subepidermal blister formation with a prominent eosinophilic infiltrate, and linear deposition of IgG and C3 along the dermoepidermal junction.
Bullous pemphigoid is an autoimmune blistering disorder typically affecting the elderly. It is caused by autoantibodies directed against hemidesmosomal proteins (BP180 and BP230) at the basement membrane zone. Because hemidesmosomes anchor the basal keratinocytes to the dermis, their destruction leads to a subepidermal blister (a blister with a thick, intact roof, rendering it 'tense' and giving a negative Nikolsky sign). Light microscopy reveals this subepidermal cleavage along with a prominent inflammatory infiltrate containing numerous eosinophils. Direct immunofluorescence highlights the pathogenesis by showing a linear band of IgG and C3 deposition precisely along the dermoepidermal junction.

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1
Analyze the clinical presentation to determine the most likely diagnosis.
An elderly patient with severely pruritic, large, tense bullae on an erythematous base, a negative Nikolsky sign, and no mucosal involvement strongly suggests bullous pemphigoid.
Differentiating blistering skin diseases relies heavily on the age of onset, morphology of the blister (tense vs. flaccid), presence of mucosal lesions, and the Nikolsky sign.
2
Identify the expected histopathological findings on light microscopy for the suspected diagnosis.
The autoantibodies in bullous pemphigoid target hemidesmosomes, causing separation at the dermoepidermal junction (subepidermal blister). The infiltrate is typically eosinophil-rich.
Understanding the target antigen (BPAg1 and BPAg2 in the basement membrane) explains the microscopic cleavage plane.
3
Identify the expected direct immunofluorescence (DIF) findings for the suspected diagnosis.
DIF will demonstrate a continuous, linear deposition of IgG and/or C3 along the basement membrane zone.
The linear pattern reflects the uninterrupted distribution of hemidesmosomes along the dermoepidermal junction.

Anahtar Kavram

Pathologic and immunofluorescence features of bullous pemphigoid
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Pathology and Biopsy Interpretation

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