A case of suppurative thyroiditis occurring in a 72-year-old woman is reported. The clinical history of this woman, treated by tianeptine for mild exogenous affective disorder and by conventional insulin therapy for long-standing insulin-dependent diabetes, was remarkable for the pseudotumoral signs which led to the simultaneous diagnosis of hypothyroidism due to Hashimoto's thyroiditis and of mycobacterium avium intracellulare suppurative thyroiditis. To our knowledge, this is the second reported case of mycobacterium avium intracellulare thyroiditis. This case is also exemplary, given its occurrence in the absence of severe immunodepression, setting apart the mild impact on the immune system of affective disorder and of long duration's insulin-dependent diabetes.