Introduction. The polyglandular autoimmune syndrome (PAS) type HI is a rare condition defined as the coexistence of autoimmune thyroid disorder with other endocrine autoimmune diseases, including type 1 diabetes, without adrenal dysfunction. PAS may associate with other non-endocrine autoimmune diseases, overlapping with the multiple autoimmune syndromes (MAS). We present a case of PAS III/MAS type 3, including autoimmune thyroiditis, autoimmune diabetes, vitiligo, lupus erythematosus, associated with adult-onset atopic dermatitis, a combination not reported previously. Case report. A 40 years old woman, registered as nurse working in dialysis unit, previously diagnosed with vitiligo, euthyroid autoimmune thyroiditis and disseminated granuloma annulare, with personal and familial history of atopic disorders, presented in our clinic for disseminated eczematous and lichenoid cutaneous rashes. She was tested positive for antinuclear, anti-double stranded DNA and anti-histone antibodies, with inflammatory syndrome and marginal lymphopenia and she was diagnosed with systemic lupus erythematosus (SLE). Subsequently, moderate hyperglycemia, positive anti-glutamic acid decarboxylase antibodies and low C-peptide level prompted the diagnosis of autoimmune diabetes. Recurrent flexural eczematous rashes, with negative epicutaneous tests but positive specific IgE tests for common allergens fulfilled the clinical criteria for the diagnosis of atopic dermatitis. The clinical, immunological and glycemic status were controlled with low doses of oral prednisone (<0.5 mg/kg), methotrexate (10mg/week), antimalarials, metformin, emollients and photoprotection. After changing her workplace, the immunosuppressive treatment could be discontinued, and the patient maintained normal immunological and biochemical profile at 6 months follow-up. This case brings a unique perspective on the evolution, associations spectrum and the management challenges of endocrine polyautoimmunity associated with atopic diathesis.