Een jongen met focale myositis in de hals

BACKGROUND: Focal myositis is a rare idiopathic pseudotumour that mostly occurs in the extremities in adults. CASE DESCRIPTION: An 8-year-old boy presented with a few months history of swelling in the neck and fever. Ultrasound investigation revealed an inhomogenous mass consistent with lymphadenitis. After nine days of antibiotic therapy, the clinical picture of fever and swelling was unchanged. MRI imaging revealed continuity of the swelling in the sternocleidomastoid muscle and a malignant process was suspected. Microscopy showed no malignant cells, however, but a lymphoplasmocytic infiltration with fibrosis and degeneration of muscle fibres, consistent with focal myositis. No intervention was undertaken and one year after presentation the tumour had regressed almost entirely. CONCLUSION: Focal myositis can present as a cervical tumour. On ultrasound, the condition is hard to distinguish from lymphadenopathy or malignancy. In cases of insufficient response to empirical antibiotic therapy, focal myositis should be considered.