Tumefactive multiple sclerosis with the presence of tumefactive demyelinating lesions (TDL) is an infrequent manifestation of multiple sclerosis. It poses a diagnostic challenge, especially in attempts to differentiate it from a central nervous system neoplasm or other demyelinating disorders, such as neuromyelitis optica spectrum disorder (NMOSD). The article reports a case of a 40-year-old female during chronic steroid therapy administered due to an episode of idiopathic transverse myelitis. The patient developed tumour-like brain lesions in the left hemispheric parietal-occipital region. The diagnostic process was hindered by extended steroid treatment and a lack of patient compliance. This case is an example of insufficient knowledge about rare forms of multiple sclerosis and the need for a holistic approach involving a through analysis of medical history and previous medical records.

demyelinating disease of central nervous system, multiple sclerosis, tumefactive multiple sclerosis