CT, Magnetic Resonance, and 18F-Fluorodeoxyglucose Positron Emission Tomography/CT Imaging Features of Mucosa-Associated Lymphoid Tissue Lymphoma Involving Medial Rectus Muscle: A Case Report

Abstract

We report a case of mucosa-associated lymphoid tissue (MALT) lymphoma involving the medial rectus muscle in a 47-year-old man along with CT, MRI, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT), and pathologic features. The lesion was manifested as a fusiform enlargement isolated to the right medial rectus muscle with involvement of its tendinous insertion. The lesion was isoattenuating to the brain on non-enhanced CT images, showing as isointense to gray matter on fast spin echo T1- and T2-weighted images with fat saturation, and showed homogeneous enhancement on contrast-enhanced CT and MR images. The maximum standardized uptake value on 18F-FDG PET/CT was 4.9 g/mL. The results of histological and immunohistochemical examinations of the specimen obtained by biopsy of the right medial rectus muscle were consistent with MALT lymphoma. It should be noted that the extraocular muscle (EOM) is a rare location for the involvement of MALT lymphoma, and MALT lymphoma of the EOM may mimic thyroid orbitopathy.

저자들은 47세 남자의 내직근을 침범한 점막 연관성 림프조직(mucosa-associated lymphoid tissue; MALT) 림프종 1예를 CT, MRI, 18F-fluorodeoxyglucose positron emission tomography/CT (18F-FDG PET/CT) 및 병리학적 소견과 함께 보고하고자 한다. 병변은 힘줄부착부위의 침범을 동반한 우측 내직근 단독의 방추형 종대로 발현하였으며, 비조영증강 CT 영상에서 뇌와 비슷한 감쇠를, 지방포화 고속스핀에코 T1- 및 T2-강조영상에서 회질과 등신호강도를 보였으며, 조영증강 CT 및 MR 영상에서 균질한 조영증강을 보였다. 18F-FDG PET/CT에서 maximum standardized uptake value는 4.9 g/mL였다. 우측 내직근의 생검에 의한 검체의 조직학적 및 면역조직화학적 검사의 결과는 MALT 림프종과 일치하였다. 외안근은 MALT 림프종에 의해 드물게 침범될 수 있으며, 외안근의 MALT 림프종은 갑상선 안병증을 닮을 수 있다.