Osteoporosis with underlying connective tissue disease: an unusual case

A 44-year-old male was initially seen by dermatologists, who noted an erythematous rash on sun-exposed areas, the back, shoulders, and upper arms. There was associated muscle weakness and significant weight loss. Investigation revealed mildly raised aspartate and alanine transaminases but normal creatine kinase. Inflammatory indices and antinuclear antibodies (ANAs) were normal. Biopsy of the rash was reported as consistent with either dermatomyositis (DM) or acute lupus erythematosus. A diagnosis of DM was made, and prednisolone was given with improvement of the rash but deteriorating myopathy. The patient was referred to the rheumatology department, and further history revealed multiple vertebral fractures after falling from standing height; these had occurred six months prior to starting steroids. Besides smoking he had no other risk factors for osteoporosis. Examination showed normal muscle strength, no muscle tenderness, and no joint abnormality. Repeat muscle enzymes were normal, and ANAs were now 1 : 100, but dsDNA antibodies and extractable nuclear antigens were normal. Investigations for osteoporosis revealed a hypergonadotrophic hypogonadism picture. Further examination indicated scanty pubic and auxiliary hair, small testicles, and mild gynecomastia. He is married, though has no children of his own. The hormonal profile raised the possibility of Klinefelter's syndrome, which was subsequently confirmed with karyotyping of 47 XXY. Hypogonadism has been established as a cause of osteoporosis in males, and in this case would explain the occurrence of fractures in the absence of other major risk factors. Systemic lupus erythematosus has been recognized in association with Klinefelter's syndrome; in view of the normal muscle enzymes, his rash is most likely due to acute discoid lupus with androgen deficiency causing muscle weakness.