Iliopsoas abscess may be classified into primary or secondary according to the pathogenesis [2,3]. In 1992, Gruenwald, et al. [4] proposed a new classification of iliopsoas abscess according the organism, therefore those due to Staphylococcus aureus should be classified as primary and those that were not caused by this bacterium as secondary. This hypothesis was refuted because many iliopsoas abscesses secondary to spondylodiscitis were caused by Staphylococcus aureus. From then until today, the classification of iliopsoas abscess is based on the form of spread of infection. Therefore, primary abscesses are due to a bacteremia distant to iliopsoas muscle and secondary iliopsoas abscess occurs as a result of direct spread of infection to the iliopsoas muscle by contiguity from an adjacent structure [2,3], such as the case presented by Mondal, et al. [1]

Recent studies place special emphasis on understanding the characteristics of primary and secondary abscesses, and it is particularly important that all authors use the same classification criteria to describe this disease [3]. So the case presented by the authors should be classified as an iliopsoas abscess secondary to spondylodiscitis due to Staphylococcus aureus.

4. Gruenwald I, Abrahamson J, Cohen O. Psoas abscess: Case report and review of the literature. J Urol. 1992;147:1624-6.