What is the differential diagnosis of an LETM lesion?
The differential is extensive and can be classified into the following: INFLAMMATORY: neuromyelitis optica, Sjogren’s, systemic lupus erythematous, Behcet’s, sarcoidosis, rheumatoid arthritis, ankylosing spondylitis, mixed connective tissue diseases, antiphospholipid syndrome, MS/ADEM. INFECTIOUS: HIV, HTLV I and II, syphilis, CMV, HSV, VZV. METABOLIC: copper deficiency, vitamin B12 deficiency. VASCULAR: dural arteriovenous fistula, infarction, fibrocartilaginous embolism. TUMOUR: primary, lymphoma, paraneoplastic. OTHERS: radiation myelopathy, trauma.
There are important clues on the MRI that narrow the differential diagnosis. Have you seen them?
Mediastinal lymphadenopathy is present on the sagittal and axial images. On the latter, hilar lymphadenopathy, parenchymal changes and subpleural plaques can also be seen.
On sagittal T2, there is long segment cord abnormality with hyperintensity and cord expansion. Appearances are consistent with a longitudinal extensive transverse myelitis (LETM). Unfortunately, contrast was not administered on this unsupervised GP referral list.