Dermatitis: Difference between revisions
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*Characteristically parakeratosis, a dermal eosinophilic infiltrate, and a perivascular lymphocytic infiltrate affecting the reticular dermis. | *Characteristically parakeratosis, a dermal eosinophilic infiltrate, and a perivascular lymphocytic infiltrate affecting the reticular dermis. | ||
*Epidermal changes are less common in lichenoid drug eruptions when compared to classic lichen planus. However, a higher concentration of necrotic keratinocyte and eosinophils in the infiltrate can be helpful in distinguishing lichenoid drug reaction from cutaneous lichen planus. A lengthy interval between the commencement of drug therapy and the onset of lesions does not exclude a diagnosis of lichenoid drug reaction. Resolution of the lesions often occurs within weeks to months after discontinuation of the offending drug.<ref name="GorouhiDavari2014"/> | *Epidermal changes are less common in lichenoid drug eruptions when compared to classic lichen planus. However, a higher concentration of necrotic keratinocyte and eosinophils in the infiltrate can be helpful in distinguishing lichenoid drug reaction from cutaneous lichen planus. A lengthy interval between the commencement of drug therapy and the onset of lesions does not exclude a diagnosis of lichenoid drug reaction. Resolution of the lesions often occurs within weeks to months after discontinuation of the offending drug.<ref name="GorouhiDavari2014"/> | ||
| [[File:Histopathology of lichenoid drug reaction|190px]] | | [[File:Histopathology of lichenoid drug reaction.jpg|190px]] || | ||
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! Lichen nitidus | |||
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*Localized granulomatous lymphohistiocytic infiltrate in an expanded dermal papilla | |||
*Thinning of overlying epidermis and downward extension of the rete ridges at the lateral margin of the infiltrate, resulting in a typical "claw clutching a ball" appearance.<ref name="Mutairi">{{cite journal |vauthors=Al-Mutairi N, Hassanein A, Nour-Eldin O, Arun J |title=Generalized lichen nitidus |journal=Pediatr Dermatol |volume=22 |issue=2 |pages=158–60 |year=2005 |pmid=15804308 |doi=10.1111/j.1525-1470.2005.22215.x |url=}}</ref> | |||
| [[File:Histopathology of lichen nitidus.jpg|190px]] || [[File:Photography of lichen nitidus.jpg|190px]] | |||
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Interface dermatitis with lichenoid inflammation, not otherwise specified, can be caused by lichen planus-like keratosis, lichenoid actinic keratosis, lichenoid lupus erythematosus, lichenoid GVHD (chronic GVHD) | Interface dermatitis with lichenoid inflammation, not otherwise specified, can be caused by lichen planus-like keratosis, lichenoid actinic keratosis, lichenoid lupus erythematosus, lichenoid GVHD (chronic GVHD), pigmented purpuric dermatosis, lichen amyloidosus, pityriasis rosea, and pityriasis lichenoides chronica.<ref name="Alsaad2005"/> Unusual conditions that can be associated with a lichenoid inflammatory cell infiltrate are HIV dermatitis, syphilis, mycosis fungoides, urticaria pigmentosa, and post-inflammatory hyperpigmentation.<ref name="Alsaad2005"/> In cases of post-inflammatory hyperpigmentation, it is important to exclude potentially harmful mimics such as a regressed melanocytic lesion or lichenoid pigmented actinic keratosis.<ref name="Alsaad2005"/> | ||
====Psoriaform dermatitis==== | ====Psoriaform dermatitis==== | ||