Skin nontumor
Dermal granulomatous and necrobiotic reaction patterns
Interstitial granulomatous drug reaction

Topic Completed: 1 June 2011

Minor changes: 22 July 2020

Copyright: 2002-2020,, Inc.

PubMed Search: Interstitial granulomatous drug reaction (dermatitis)

Mowafak Hamodat, M.B.Ch.B., M.Sc.
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Cite this page: Hamodat M. Interstitial granulomatous drug reaction. website. Accessed October 26th, 2020.
Definition / general
  • Reaction due to beta blockers, calcium channel blockers, lipid lowering agents, ACE inhibitors, diuretics, NSAIDs, antihistamines, antidepressants and oral hypoglycemic agents; often more than one of the above
  • Mean duration of 5 years before onset of eruptions
  • Resolves a mean 8 weeks (range 1 - 40) after drug is stopped
  • May be due to exaggerated immune response to drugs
Clinical features
  • Violaceous to erythematous, nonpruritic plaques with bizarre shapes, or annular morphology on skin folds (axilla, inner arms, groin, medial thighs and popliteal fossa)
Case reports
Microscopic (histologic) description
  • Diffuse granulomatous dermatitis with interstitial histiocytes and giant cells near collagen and elastic fibers, often with piecemeal fragmentation of collagen, giant cell engulfment of elastic fibers and variable interstitial mucin (J Cutan Pathol 1998;25:72)
  • Usually interface dermatitis with basilar vacuolopathy and focal dyskeratosis with lymphocytes at dermoepidermal junction
  • Usually tissue eosinophilia, lymphoid atypia with hyperchromatic nuclei, convoluted nuclear contours (including a few cerebriform nuclei in dermis), variable involvement of hair follicles and acrosyringia
  • Rare collagen necrobiosis
  • Usually no fibrin deposition within vessels or vasculitis
Microscopic (histologic) images

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Figure 1: ankle plaques; 2 - 4: diffuse interstitial and perivascular histiocytic infiltrate in dermis and subcutis, with occasional lymphocytes and eosinophils; epidermis has basilar vacuolopathy and dermoepidermal lymphocytes

Various images

Differential diagnosis
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Image 01 Image 02