International Journal of Medicine and Health Development (Jan 2006)
A local experience of ultrasonography in the diagnosis and treatment of tropical pyomyositis
Abstract
Background: Tropical pyomyositis is endemic in this environment yet a good number of patients with this condition are not detected on time.[1],[5],[19] Clinical diagnostic criteria are often misleading and recourse to imaging techniques would appear mandatory if morbidity and mortality must be controlled. Aim: To identify the clinical and sonographic features of pyomyositis which could facilitate diagnosis. Materials and Methods: The demographic, clinical and sonographic findings in 48 consecutive patients aged between six months and 78 years who initially presented with palpable masses of the neck, abdomen, chest and limbs, 46 of which eventually proved to be pyomyositis were retrospectively compiled and analysed Results: The most affected age group was the (1-20 years) age groups. More males than females, as well as more rural .than urban subjects were affected. All referring physicians except 12 missed the diagnosis. The diagnosis of pyomyositis was correctly established with the aid of sonography in forty-six cases while two cases proved to be false positive. The most common causative organism was staphylococcus aureus. Two categories of lesions were identified sonographically namely:(l) The small ovoid solid hypoechoic lesion showing discrete swollen linear muscle fibres seen in the early part of the disease process. (2) The large partly solid partly fluid inhomogenously hypoechoic lesion demonstrating areas of partial myonecrosis usually seen in the later stages of the disease. The most frequently affected muscles in this series were those of the anterior abdominal wall. Conclusion: Ultrasound is effective in both diagnosis and therapy. It could enable a precise diagnosis to be made so long as the ultrasonic findings are evaluated in conjunction with the clinical features and laboratory findings such as ESR, WBC and culture/sensitivity of infected muscle aspirates. False-positives of pyomyositis are not uncommon and histological analysis of muscle biopsy specimens may occasionally be mandatory to arrive at a definite diagnosis. Sonography offers good guidance at both needle aspiration and muscle biopsy. It is easily available, cheap and radiation free.
