PMC9626364_01
MR exam performed in 2020, showing a multi-loculated heterogeneous mass with a solid component (thin arrow) hypointense both on T2 (A, D) and on T1 (B), isointense on T1 fat-sat (C), hyperintense on contrast-enhanced T1 fat-sat (E, F); note the cystic component showed by the arrow, with a liquid level, markedly hyperintense on T2 (A, D).. Axial TSE T2w (A), axial SE T1w (B), axial vibe T1 (C), sagittal TSE T2w (D), sagittal contrast-enhanced T1 vibe (E), and axial contrast-enhanced T1 vibe (F).
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After several years, a new follow-up MR exam performed at the end of 2020 (Table 1) showed the presence of a new richly vascularized solid mass located in the pre-coccigeal region expanding in the fat tissue of the ischio-rectal fossae with confluent grape-shaped nodules (Fig. 1).
MR exam performed in 2021, showing a bigger multi-loculated heterogeneous mass with a solid component hypointense both on T2 (A, E) and on T1 (F), heterogeneously hyperintense on STIR (B), with restricted diffusion (C, D) and hyperintense on contrast-enhanced T1 (G); also in this case there is a cystic component showed by the arrow, with a liquid level, markedly hyperintense in T2 (A, E).. Sagittal TSE T2w (A), axial STIR (B), axial DWI b1000 (C), axial ADC map (D), coronal TSE T2w (E), axial SE T1w (F), and axial contrast-enhanced T1 vibe (G).
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The recurrence was treated with IM and a new MR exam performed 6 months later showed the progression of the disease, with volumetric increase of the lesion (mean diameter of 4.5 cm vs 3.9 cm) (Fig. 2).