Variably thick bundles of smooth muscle actin-positive soft tissue encircled the whole tumors, forming a continuous pseudocapsule.
Classic HCC shows arterial phase enhancement followed by a washout in the portal and/or delayed phase with a pseudocapsule around the nodule (Fig. 1).
As in the case of SK-TRβ tumors, they are surrounded by a pseudocapsule and present a reduced number of invasion fronts (Figure 7C).
The tumour is fairly well defined despite its malignant nature because of a pseudocapsule, but may exert a mass effect or encase neurovascular bundles.
However, the presence of a pseudocapsule is non-specific and can be seen in up to 60% of RCCs as well [32, 52].
Synovial sarcoma often presents cystic areas mixed with necrotic areas, and some of those tumours may also present a pseudocapsule, due to the compression of adjacent compressed lung tissue, with packed blood vessels and granulation tissue [24].
Both histotypes can be confused with an MM, although synovial sarcoma usually affects younger patients, presents a more localised aspect, grows faster and often presents a pseudocapsule, which is typically absent in the MM [25, 26].
In the PZ, it is possible to find a round-shaped region characterised by inhomogeneous, low-signal intensity on T2-WI, with a pseudocapsule (scored as 2/5), together with ring enhancement on DCE and restriction on DWI (scored as 4/5).
A pseudocapsule consists of compressed renal tissue and fibrous tissue.
The sensitivity of CT in depicting a pseudocapsule is low (10 26%), whereas MRI shows a moderate to high sensitivity in depicting the pseudocapsule (54 93%) [ 41, 42].
