Clinicians who diagnose lichenoid granulomatous dermatitis (LGD) may wish to look for dermal eosinophilia, psoriasiform epidermal changes, periadnexal inflammation, and red blood cell extravasation in an effort to improve diagnosis of this condition, a study in the Journal of the American Academy of Dermatology reports.

A total of 56 cases of LGD were collected from 3 different laboratory information systems across the United States. Overall, the included cases demonstrated band-like inflammation of lymphocytic infiltrates in the papillary dermis, groups of histiocytes with/without giant cells admixed with the lichenoid inflammatory infiltrate or in the mid to reticular dermis, or interface tissue reaction with basilar keratinocyte apoptosis.

The researchers reviewed cases to identify data on deep perivascular infiltrates, eosinophils, epidermal atrophy, granuloma subtype, parakeratosis, periadnexal inflammation, plasma cells, psoriasiform epidermal changes, pseudoepitheliomatous hyperplasia, red blood cell extravasation, and vasculitis.

There were 3 categories of diagnoses based on clinicopathologic correlations: drug-induced hypersensitivity, non-drug-induced hypersensitivity, and solitary lichenoid lesions. Drug eruption and lichenoid keratosis comprised the most common clinical correlates in the case cohort (39.3% and 19.6%, respectively). The frequency of diagnoses based on tattoo reaction, postherpetic dermatitis, and scabies or postscabietic dermatitis was 7.1% for each clinical correlate (n = 4 for each).

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In addition, both pigmented purpuric dermatosis and lichen striatus each accounted for 5.4% (n = 3 for each) of LGD cases. Drug hypersensitivity was significantly associated with dermal eosinophils (P =.005) and psoriasiform epidermal changes (P =.055). Conversely, tattoo reaction and postherpetic dermatitis were significantly associated with perineural (P =.049) and perifollicular (P =.003) inflammation. In cases of pigmented purpuric dermatosis, red blood cell extravasation was also helpful for diagnosis (P =.049).

Limitations of the analysis include its retrospective nature, as well as the small sample size of the final cohort.

The researchers concluded that “[c]linical morphology and history, in tandem with attention to dermal eosinophilia, psoriasiform changes, and periadnexal inflammation, permit more specific diagnostic guidance” of LGD.

Disclosure: None of the study authors declared affiliations with the pharmaceutical industry. Please see the original reference for a full list of authors’ disclosures.

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Reference

Braswell DS, Hakeem A, Walker A, et al. Lichenoid granulomatous dermatitis revisited: A retrospective case series [published online August 1, 2019]. J Am Acad Dermatol. doi:10.1016/j.jaad.2019.05.100