Pathology of Interstitial Granulomatous Dermatitis
granulomatous dermatitis with cutaneous cords and arthritis ;
Rheumatoid papules ; Palisaded and neutrophilic granulomatous
Interstitial granulomatous dermatitis is a rare systemic disorder which is usually associated with systemic auto-immune conditions or malignant lymphoproliferation.
Clinically, it may be present as linear (the 'rope sign') or arciform subcutaneous cords, papules or plaques.
Different patterns have been described:
(i) May resemble incomplete granuloma annulare, with an interstitial and perivascular dermal infiltrate of neutrophils, histiocytes, lymphocytes and sometimes eosinophils.
Dermal collagen appears basophilic.
(ii) There may be small granulomas composed of palisade of histiocytes around basophilic collagen fibers.
Some neutrophils may be present.
The changes are usually prominent in the lower half of the dermis.
Clue to diagnosis of interstitial granulomatous dermatitis with arthritis:
A granuloma annulare-like dermatitis with neutrophils and eosinophils usually present in the lower two thirds of the dermis.
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