Klinefelter's syndrome accompanied by mixed connective tissue disease and diabetes mellitus

We report a rare case of Klinefelter's syndrome (KS) with mixed connective tissue disease (MCTD), diabetes mellitus (DM) and several endocrine disorde rs, A 57-year-old man presented with polyarthritis and tapering fingers wit h Raynaud's phenomenon on admission. In addition to a karyotype of 47, XXY, a marked restrictive change in respiratory functional test, a myogenic pat tern in electromyogram, the positive tests for anti-RNP antibody indicated that this was a case of KS complicated with MCTD, The patients also present ed DM with insulin resistance, hyperprolactinemia, slight primary hypothyro idism and hypoadrenocorticism, The mechanism for these coincidences remains to be elucidated.