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Granulomatous but non-infectious disorders

Interstitial granulomatous drug reaction (dermatitis)

Reviewer: Mowafak Hamodat MB.CH.B, MSc., FRCPC, Eastern Health, St. Johns (Canada) (see Reviewers page)
Revised: 3 July 2011, last major update June 2011
Copyright: (c) 2002-2011, PathologyOutlines.com, Inc.


● 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

Case reports

● 74-year-old woman with violaceous/erythematous nonpruritic plaques for 18 months (Arch Pathol Lab Med 2004;128:e129)
● Delayed cutaneous hypersensitivity reaction to hirudin (Arch Pathol Lab Med 2001;125:1585)

Clinical description

● Violaceous to erythematous, nonpruritic plaques with bizarre shapes, or annular morphology on skin folds (axilla, inner arms, groin, medial thighs and popliteal fossa)

Micro 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

Micro images

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

● Cutaneous T cell lymphoma: similar due to cerebriform nuclei in epidermis
● Erythema annulare centrifugum
● Granuloma annulare: vasculitis or vasculopathy present; necrobiosis; usually no eosinophils and no interface change
● Subacute cutaneous SLE

End of Skin-nontumor > Granulomatous but non-infectious disorders > Interstitial granulomatous drug reaction (dermatitis)

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