Reactive and infective dermatoses associated with adult-onset immunodeficiency due to anti-interferon-gamma autoantibody: Sweet's syndrome and beyond.

Immunodeficiency due to anti-interferon-gamma autoantibody (anti-IFN-γ autoAb) is an emerging adult-onset immunodeficiency syndrome predominantly found in Southeast Asians. It is associated with severe or disseminated infections caused by non-tuberculous mycobacteria (NTM) and other opportunistic pathogens. We describe 3 patients with anti-IFN-γ autoAb who developed reactive and infective dermatoses, and thoroughly review the existing literature on dermatoses associated with the immunodeficiency syndrome. Case 1 developed Sweet's syndrome associated with Mycobacterium chelonae lymphadenitis and penicilliosis. Case 2 suffered from multiple episodes of lobular panniculitis during recurrent infections by NTM, Penicillium marneffei and Burkholderia pseudomallei. Both cases responded to immunomodulating agents including corticosteroid and non-steroidal anti-inflammatory drugs. Case 3 had direct skin invasion by M. chelonae and responded to prolonged anti-mycobacterial therapy. A novel working algorithm is proposed for the diagnosis and treatment of these patients who may be encountered by the dermatologist and histopathologist in clinical practice.