Anaplastic large cell lymphoma of the vertebra masquerading as tuberculous spondylitis: potential pitfalls of conventional imaging

Abstract

A 26-year-old woman presented with a 6-month history of progressive neck pain associated with a 1-month history of fever, cough, and weight loss. Physical examination revealed a febrile patient with a temperature of 39.1 C. There were localized tenderness and reduced range of motion at the cervicothoracic region of the spine. There was no neurological deficit. Laboratory findings revealed a raised white blood cell count of 21.6 9 10/L. There was elevation of inflammatory markers such as erythrocyte sedimentation rate (79 mm/hr) and C-reactive protein (137 mg/L). Serum lactate dehydrogenase and tumor markers such as alpha-fetoprotein, beta-human chorionic gonadotropin, carcinoembryonic antigen, and CA-125 levels were normal. Radiographs of the cervical spine and chest revealed bony erosions in the C7 and T1 vertebrae (Fig. 1, arrowhead), and right upper lobe consolidation with air bronchograms (Fig. 1, arrow). Contrast-enhanced computed tomography (CT) scan showed bony erosions with pathological fractures involving the C7 to T3 vertebrae (Fig. 2a, b, arrows). An adjacent large paravertebral thick-walled rim-enhancing lesion was seen (Fig. 2c, arrow). There was lung consolidation in the posterior segment of the right upper lobe (Fig. 2d, arrow) as well as prominent mediastinal and retroperitoneal (Fig. 2e, arrow) lymph nodes. Gadolinium-enhanced magnetic resonance imaging (MRI) of the spine was performed to evaluate the soft tissues and spinal cord. MRI revealed altered marrow signal and abnormal enhancement in the C7 to T4 vertebrae with adjacent enhancing subligamentous and epidural masses as well as mild kyphosis (Fig. 3, arrows). There was relative sparing of most of the intervertebral disks. The radiographic, CT, and MRI findings were typical of pulmonary tuberculosis (TB) with tuberculosis spondylitis. The clinical findings further corroborated this presumptive diagnosis. However, multiple induced sputum specimens were negative for acid-fast bacilli smears and molecular TB tests. Moreover, the vertebral destruction seemed more extensive than expected for TB that had been symptomatic for only 6 months. Hence the possibility of an alternative diagnosis was entertained. [F]fluorodeoxyglucose positron emission tomography/ computed tomography (FDG-PET/CT) scan (Biograph mCT 64-slice, Siemens AG, Erlangen, Germany) was subsequently performed to assess the extent and pattern of disease, and to determine the most suitable site for biopsy. The PET/CT scan showed FDG-avid vertebral and paravertebral masses (standardized uptake value, SUVmax 28.3) extending from the C7 to T4 vertebrae (Fig. 4a, arrow), FDG-avid lung consolidation with air bronchograms (SUVmax 7.9) in the right upper lobe (Fig. 4b, arrows), FDG-avid lesions in both kidneys (SUVmax 11.1) (Fig. 4c, arrows), and FDG-avid retroperitoneal (SUVmax 7.6) lymphadenopathy (Fig. 4d, arrows). In addition, the spleen (SUVmax 8.3) and bone marrow (SUVmax 5) showed diffusely increased FDG uptake (Fig. 4a, e, arrowheads). The pattern of disease demonstrated on L. K. Khor (&) S.-J. Lu Department of Diagnostic Imaging, National University Hospital, 5 Lower Kent Ridge Road, Singapore 119074, Singapore e-mail: superkhor@hotmail.com