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Abstract

Granuloma annulare (GA) is a prototypic palisading granulomatous dermatitis characterized by discrete foci of interstitial granulomatous inflammation predominated by mononuclear histiocytes palisading around altered collagen accompanied by prominent mesenchymal mucin deposition. Although idiopathic in many cases, there is a potential link with certain diseases including thyroid disease, diabetes mellitus and certain rheumatologic conditions. A variant of granuloma annulare falls under the designation of subcutaneous granuloma annulare (SGA) and is characterized by a subcutaneous localization and central fibrinoid necrosis reminiscent of a rheumatoid nodule. We describe a case of drug associated SGA. A 16-year-old female presented to the Pediatric Rheumatology clinic with a six-month history of firm subcutaneous nodules on multiple fingers, which had progressively increased in size and pain. An initial biopsy suggested rheumatoid nodules; however, she had neither clinical evidence of arthritis nor serologic markers consistent with rheumatoid arthritis. Slide review demonstrated discrete nodular foci of fibrinoid necrosis palisaded by histiocytes within the subcutaneous fat, diagnostic of SGA. Her history was notable for idiopathic intracranial hypertension. She was recently started on acetazolamide, which preceded her cutaneous eruption; the nodules worsened with each dose increase. The patient had near-complete resolution of the nodules within two weeks of discontinuing acetazolamide. Acetazolamide, a carbonic anhydrase inhibitor (CAI), has been temporally linked to SGA in one prior case. Carbonic anhydrase inhibition affects macrophage function, enhancing their survival and activation, which may underlie granuloma annulare associated with acetazolamide and, less commonly, topiramate, another weak CAI implicated in conventional but not subcutaneous forms.