Synopsis
Choose, consent, collect and transport skin for direct immunofluorescence, interpret major deposit patterns in clinical context, and route blistering, vasculitic and connective-tissue presentations to the right urgency of specialist care.
- Direct immunofluorescence detects immunoglobulin, complement or fibrin deposited in the patient's skin; it is different from routine H&E histology and indirect immunofluorescence performed on serum.
- Autoimmune blistering investigation usually needs two separately selected punch biopsies: a fresh blister edge or lesional sample in formalin for H&E and intact perilesional skin in the laboratory's fluorescence transport system for DIF.
- For dermatitis herpetiformis, choose normal-appearing skin immediately beside a fresh lesion; eroded, excoriated or directly involved tissue can lose the diagnostic granular IgA signal.
Key red flags
Rapid spread, Nikolsky-positive or painful skin, fever, hypotension, extensive erosions, eye pain or visual change, dysphagia, reduced intake or urine, breathing symptoms, genital involvement, immunosuppression or a vulnerable age group requires urgent specialist triage before routine biopsy booking.
Pain, flat duskiness, detachment, fever or multi-site mucositis points to an emergency drug reaction or other severe disease in which referral precedes an elective test pathway.
Investigation priorities
Define the leading disease, choose lesion age and preserve a record for clinicopathological correlation.
Management branches
A blistering, erosive, purpuric or interface eruption may need immunofluorescence.
- Assess observations, skin pain and extent, hydration, infection, mouth, eyes, genital and airway involvement and systemic renal, gastrointestinal, neurological or respiratory features.
- Arrange emergency admission and dermatology review for instability or threatened epithelium and begin time-critical supportive or disease-directed care without waiting for an ideal specimen.
H&E and DIF are both needed to investigate a stable patient.