Tropical Myositis: A Not-So-Tropical Diagnosis in a Febrile Type 1 Diabetic Patient.

Introduction: Tropical myositis - also known as pyomyositis - is a subacute, primary infection of skeletal muscle. Long considered a diagnosis exclusive to tropical climates, recently it has been reported increasingly in historically nontropical climates. We present a case of tropical myositis in Madison, Wisconsin, occurring in a febrile type 1 diabetic patient without travel or known exposure.

Case presentation: A 35-year-old male with a history of von Willebrand disease, type 1 diabetes, and financial insecurity resulting in insulin rationing presented with 2 weeks of generalized weakness. On exam, he had a multitude of large, erythematous "bumps" across his body, which had been increasing in size for more than 2 weeks. His blood glucose was 518, with leukocytosis and labs supportive of diabetic ketoacidosis. Computed tomography revealed extensive intramuscular and subcutaneous abscesses of the left chest, bilateral erector spinae, right gluteal muscles, bilateral thighs, left leg, and left upper and lower arm. Broad-spectrum antibiotics were initiated, as was treatment for diabetic ketoacidosis. Blood and urine cultures revealed oxacillin-susceptible Staphylococcus aureus. After clinical stabilization, he underwent initial incision and drainage of the abscesses. His condition would require 14 more operative incision and drainage procedures and wound closure attempts before he was discharged to a rehab facility after more than a month-long hospitalization.

Discussion: Severe tropical myositis is associated with high morbidity and high use of health care resources. The exponential rise in cases in the United States in recent years risks further stressing an already-burdened health care system. We explore potential causes of the increase in cases of tropical myositis in nontropical regions, including increasing rates of diabetes and poverty and climate change. Recent data suggest that the large majority of tropical myositis cases are caused by Panton-Valentine leukocidin toxin-producing Staphylococcus aureus strains. There is a theoretical mitigation of disease severity when patients receive early protein synthesis inhibitor antibiotic treatment, though these findings are limited to case reports and observational studies and lack controlled clinical trials. This case highlights the need for early identification, antibiotic administration, and surgical source control in suspected cases of tropical myositis.