Differential Diagnosis of Vertebral Lesions with paraspinal Mass with MRI

PURPOSE: To assess the characteristic features of MR findings which would be useful for the differentiation of various spinal diseases involving paraspinal soft tissue mass. MATERIALS AND METHODS: We retrospectively reviewed MR findings in 31 cases(M:F=20:11) of spinal disease in which paraspinal mass was involved. The breakdown of cases was as follows : spinal tuberculosis, 12; spinal metastasis, 13; multiple myeloma, 3; pyogenic spondylitis, 2; spinal aspergillosis; 1. RESULTS: The pattern of bone marrow invasion in spinal metastasis, multiple myeloma, spinal tuberculosis and aspergillosis was mixed ; focal, homogeneously diffuse and inhomogeneously patterns were seen. Pyogenic spondylitis showed inhomogeneously diffuse invasion; an intravertebral abscess was seen in the only five cases of spinal tuberculosis. Vertebral posterior compartment invasion was observed in seven cases of spinal tuberculosis, two of multiple myeloma, the one case of spinal aspergillosis and in all 13 cases of spinal metastasis. This and multiple myeloma showed no disc space invasion, in any case, but all cases of infectious spondylitis showed such invasion. Peripheral rim-enhancement in the paravertebral mass was seen in 11 cases of spinal tuberculosis, one case of pyogenic spondylitis and the case of aspergillosis. Bilobate anterior epidural mass was noted in 60% of spinal tuberculosis cases, 36% of spinal metastasis and one case of pyogenic spondylitis. CONCLUSION: MR findings of spinal disease involving a paraspinal soft tissue mass were useful for differentiation.

CT Findings in Differential Diagnosis of Benign and Malignant Parotid Tumors

PURPOSE: To evaluate CT findings which may help differentiate benign from malignant parotid tumors. MATERIALS AND METHODS: The CT findings of seventy-one cases with surgically-proven parotid tumors were retrospectively analysed for size, location, margin, internal density, adjacent tissue plane and lymphadenopathy. RESULTS: The margin of the mass was smooth and sharp in most benign tumors (89.5%), and irregular or indistinct in twelve which were malignant (75%, p<0.01). With regard to internal density, 70.2% of benign tumors were homogeneous (similar to muscle) and 81.3% of malignant tumors were heterogeneous (p<0.01). When analysing low density patterns within the mass, focal low densities in benign tumors (11/17) and diffuse or scattered multifocal low densities in those which were maligant (8/13) were frequently seen. Three malignant tumors invaded adjacent muscles, the parapharyngeal space, and bones, each in one case, and twelve malignant and one benign tumor infiltrated the adjacent fascia or subcutaneous fat layer. In five patients with a malignant tumor, obliteration by the mass of the fat plane between the mastoid tip and styloid process was noted, suggesting facial nerve invasion, while in three cases of malignancy, lymphadenopathy greater than 1cm was seen. CONCLUSION: In differentiating malignant and benign parotid tumors, the presence of irregular or indistinct margin of the mass, and invasion of adjacent structures, are important. Lymph node enlargement greater than 1cm and diffuse internal low densities, which may suggest necrosis or cystic change were also helpful in differential diagnosis.