MR imaging findings of focal myositis: a pseudotumour that may mimic muscle neoplasm.

Abstract

OBJECTIVE:

The authors describe magnetic resonance (MR) findings in eight patients with histologically confirmed focal myositis.

MATERIALS AND METHODS:

In each patient, axial TSE T1-weighted and fast short-tau inversion recovery (STIR) images were obtained using a 1.5-T MR scanner. Three patients also underwent dynamic contrast-enhanced MR examination using a GE T1-weighted sequence. The following features were evaluated: anatomical distribution, extent of the involvement, signal intensity characteristics, dynamic enhancement pattern and outcome at follow-up examinations.

RESULTS:

Seven of eight lesions were located in the lower extremities, one of eight in the arm; four of eight involved part of a muscle, two of eight diffusely involved a muscle and two of eight showed multifocal involvement of two or more muscles. All lesions were hyperintense on fast-STIR images: the hyperintensity was homogeneous in six of eight and inhomogeneous in two of eight. On T1-weighted unenhanced images, all lesions but two appeared isointense or slightly hypointense in comparison to normal muscles; two lesions showed a slight hyperintensity. Dynamic enhancement pattern corresponded to the type usually seen in benign soft tissue lesions. All lesions disappeared.

CONCLUSION:

Focal myositis is an uncommon pseudotumour which should be considered in the differential diagnosis of muscular masses and myopathies.

• Authors: Michele Gaeta, Silvio Mazziotti, Fabio Minutoli, Antonino Genitori, Antonio Toscano, Carmelo Rodolico, Alfredo Blandino
• Journal: Skeletal radiology (Skeletal Radiol) Vol. 38 Issue 6 Pg. 571-8 (Jun 2009) ISSN: 1432-2161 [Electronic] Germany
• PMID: 19255757 (Publication Type: Journal Article)

Topics

• Adult
• Aged
• Diagnosis, Differential
• Female
• Humans
• Magnetic Resonance Imaging (methods)
• Male
• Middle Aged
• Muscle Neoplasms (pathology)
• Muscle, Skeletal (pathology)
• Myositis (pathology)
• Young Adult