title: Endometriosis of the vastus lateralis muscle.
abstract: We report an unusual case of a woman who sought medical attention for a painful mass within her anterolateral left thigh. The patient's symptoms waxed and waned with her menses. Magnetic resonance imaging revealed a 3 cm mass isointense to muscle and surrounded by a rim of decreased signal intensity on T1-weighted images. T2-weighted images with fat saturation revealed a low signal intensity mass with a surrounding rind of high signal intensity edema. Based on its magnetic resonance imaging characteristics, the lesion was initially thought to represent the sequela of prior trauma or perhaps a small fibrous tumor. An excisional biopsy of the mass, however, revealed endometrial tissue, and a pathologic diagnosis of intramuscular endometriosis was rendered.
authors.affiliation: Radiology, The University of Chicago, Chicago, IL, USA. patbasu@yahoo.com
authors.forename: Pat Auveek
authors.initials: PA
authors.lastname: Basu
authors.forename: Anil K
authors.initials: AK
authors.lastname: Kesani
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Stacy
authors.forename: Terrance D
authors.initials: TD
authors.lastname: Peabody
mesh_terms: D000328:Adult; D001706:Biopsy; D003937:Diagnosis, Differential; D004715:Endometriosis / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D009135:Muscular Diseases / Q000175:diagnosis*; D015641:Radiography, Interventional; D013848:Thigh