Lichenoid granulomatous dermatitis revisited: A retrospective case series.

Background: Lichenoid granulomatous dermatitis (LGD) is an uncommon reaction pattern for which clinical correlates can be difficult to establish. LGD combines vacuolar degeneration with variable types of granulomas.

Objective: To determine clinical correlates of LGD.

Methods: The laboratory information systems at the University of Florida, the Medical College of Wisconsin, and Inform Diagnostics Research Institute were queried to identify 56 cases of LGD. Cases were reviewed for information regarding eosinophils, plasma cells, deep perivascular infiltrates, granuloma subtype, parakeratosis, epidermal atrophy, psoriasiform epidermal changes, pseudoepitheliomatous hyperplasia, periadnexal inflammation, vasculitis, and red blood cell extravasation.

Results: The most common clinical correlates were drug eruption (39.3%, n = 22) and lichenoid keratosis (19.6%, n = 11). Tattoo reaction, postherpetic dermatitis, and scabies or postscabietic dermatitis each accounted for 7.1% (n = 4) of cases. Pigmented purpuric dermatosis and lichen striatus each accounted for 5.4% (n = 3) of cases. Dermal eosinophils (P = .005) and psoriasiform epidermal changes (P = .055) were associated with drug hypersensitivity. Perineural (P = .049) and perifollicular (P = .003) inflammation were associated with tattoo reaction and postherpetic dermatitis. Red blood cell extravasation was helpful in cases of pigmented purpuric dermatosis (P = .049).

Limitations: This study is limited by its retrospective nature and statistical power.

Conclusion: Dermal eosinophilia, psoriasiform epidermal changes, periadnexal inflammation, and red blood cell extravasation might aid in the clinical diagnosis of patients with LGD.