lichenoid infiltrate

Etiology

 dermatomyositis
 erythema multiforme
 fixed drug reaction
 graft versus host disease
 lichen nitidus
 lichen planus
 lichen sclerosus et atrophicus
 lichen striatus
 pityriasis lichenoides chronica
 pityriasis lichenoides et varioliformis acuta
 poikiloderma atrophicans vasculare
 skin graft rejection
 subacute cutaneous lupus erythematosus

Examples

 cutaneous syphilis / secondary syphilis : psoriasiform pattern + lichenoid infiltrate with histiocytes great clue. Plasma cells ++

• https://twitter.com/JRamirezMD/status/782747788907991040

 lichen striatus (lichenoid inflammation and perieccrine inflammation ) quite old lesion

• https://twitter.com/faisalmohammedi/status/834896649977802754

Diagnosis of lichenoid infiltration

 eosinophils ?

• lichenoid drug reaction

 sawttooth pattern

• LP

 follicle involvment and bone marrow transplantation

• GVHD

 sun damage / atrophy RR

• regressed melanoma
• lichenoid keratosis

 S+D / superficial+deep

• hypertrophic lupus

Diagnosis of interface inflammatory infiltration

 no S+D / no superficial+deep

• lymphocytic atypia : mycosis fungoides
• rust, wedge shaped erythrocytes : PLEVA
• full thickening necrotic keratinocytes : EM
• full thickening necrosis : EM
• follicular involvment : GVHD

 S+D / superficial+deep

• plasmocytes, thin RR : syphilis
• papillary edema : light
• lichen striatus
• mucin, follicular pluging, BM increase, IF+ : SLE / DM
  • epidermal atrophy : DM
  • no epidermal atrophy : SLE

Ref: @loyoladermpath

Digital cases

 UI:902 - Lichen planus
 UI:881 - Lichen sclerosis et atrophicus

See also

 lesional patterns

• cutaneous lesional patterns

 dermal infiltrates - dermal infiltration