Patient selection: diabetes mellitus
Mechanism: uncertain, but possibly small vessel disease and/or microatheroemboli
Features:
(1) The patient experiences an abrupt onset of atraumatic focal pain and weakness in an extremity, usually without clinical signs of systemic illness at the onset.
(2) The area shows generalized tenderness and swelling.
(3) Pain is present at rest and is made worse with movement.
(4) The patient has poorly controlled diabetes with hyperglycemia and the patient often has some form of end-organ disease (retinopathy, nephropathy, etc.)
(5) MRI shows muscle edema with abnormally high signal intensity in T2 images.
(6) A biopsy shows muscle edema and ischemic necrosis.
(7) Cultures are negative, including an adequate anaerobic culture.
(8) There is no evidence of thromboembolic disease in large blood vessels.
(9) A compartment syndrome may develop in severe cases.
(10) The serum creatine kinase is elevated.
(11) The white blood cell count and other markers of systemic illness may be normal, at least initially.
Differential diagnosis:
(1) infectious myonecrosis (gas gangrene, Fournier's gangrene, necrotizing cellulitis, pyomyositis)
(2) peripheral vascular disease involving large arteries
(3) rhabdomyolysis (usually a generalized process)
(4) autoimmune myopathy (polymyositis, dermatomyositis)
(5) inflammatory myopathy (localized nodular myositis, myositis ossificans, proliferative myositis)
(6) diabetic neuropathy or plexopathy
(7) muscle tumor
