The role of image in the diagnosis of pseudotumor lesions: a pictorial essay

The clinical-radiological differentiation between neoplastic and pseudotumoral lesions has an important role in therapeutic approach, with repercussions on the conduct to be taken. When facing an expansive lesion, in addition to neoplasms, a list of differential diagnoses must be considered, including inflammatory, infectious, hemorrhagic lesions, among others. In this context, the role of imaging methods is highlighted in order to anticipate surgical management in the presumption of an aggressive neoplasm or, on the other hand, avoid an unnecessary invasive procedure. Objectives: To identify the warning signs of pseudotumor lesions in imaging studies. Methodology: Retrospective pictorial review of the archives of Diagnostic Imaging service of Santa Casa de São Paulo, between 2010 and 2020. Results: The warning signs that indicate a probable pseudotumoral lesion include spontaneous hypersignal in T1, marked hyposignal in T2, absence of significant expansive effect, cavitated lesion with high signal in diffusion, incomplete ring impregnation, restricted peripheral ring diffusion and spectral relations (choline / creatine) lower than 2. Each of these distinguishing features is discussed and exemplified. Conclusions: Although the distinction between expansive neoplastic and pseudotumoral lesions is not always direct, the systematic use of the exposed criteria allows greater assertiveness in the differential diagnosis. If the diagnostic doubt persists, therapeutic proof tests have a fundamental role in this context and, unfortunately, in some cases the final diagnosis will only be possible with biopsy.