PMC5362888_01
Right lateral view of the abdomen. Note the over-distended urinary bladder, the cranial margins appear irregular and thickened (black arrow); a radiotransparent spot is notable in the middle of the urinary bladder (white arrow)
10.1177_2055116915585019-fig1.jpg
PMC5362888_01_10.1177_2055116915585019-fig1.jpg
fig1-2055116915585019
Abdominal radiographs (right laterolateral and ventrodorsal projection) showed an over-distended urinary bladder with irregular cranial margins and the presence of a small radiotransparent area in the urinary bladder lumen, compatible with air (Figure 1).
Abdominal ultrasound findings. Longitudinal scan after urethral catheterisation and distension with 0.9% saline solution. (a) An irregular, rounded 4.6 x 4.2 x 4 cm lesion arises from the apex and the dorsal wall of the urinary bladder. (b) The trigone and the urethra appear normal
10.1177_2055116915585019-fig2.jpg
PMC5362888_01_10.1177_2055116915585019-fig2.jpg
fig2-2055116915585019
On abdominal ultrasound, the urinary bladder lumen was entirely occupied by the presence of a mass of mixed echogenicity (Figure 2a); mild bilateral pyelectasia (1 mm) was also detected. The cat was sedated, and the urethra was catheterised and the urinary bladder distended with sterile 0.9% saline solution for better evaluation: an irregular vascularised lesion measuring 4.6 x 4.2 x 4.0 cm arising from the cranial and dorsal wall of the urinary bladder was observed (Figure 2b); the urethra and the trigone were not involved.
(a) Gross aspect of the urinary bladder and mass during surgery: note the thickened urinary bladder wall and the presence of a pedunculated mass that was filling the urinary bladder. (b) Gross examination: the mass measured 6.0 x 4.5 x 3.2 cm, had a fibroelastic consistency and was white to pinkish in colour; the surface is characterised by the presence of erosion and haemorrhages
10.1177_2055116915585019-fig3.jpg
PMC5362888_01_10.1177_2055116915585019-fig3.jpg
fig3-2055116915585019
A ventral cystotomy was performed to examine the bladder mucosa and the mass appeared pedunculated and extended from the craniodorsal wall of the urinary bladder into the lumen (Figure 3a).
Microscopic findings. (a) Section of the urinary bladder mass characterised by a proliferation of spindle cells irregularly arranged in interwoven and concentric bundles. In the central part of the lesion a degenerative mucinous area is observed (haematoxylin and eosin, x 4). (b) High magnification of the spindle cell pattern intertwined with a minimal deposition of amorphous eosinophilic extracellular matrix; in the right upper corner, vessels of small and medium size are observed (haematoxylin and eosin, x 10)
10.1177_2055116915585019-fig4.jpg
PMC5362888_01_10.1177_2055116915585019-fig4.jpg
fig4-2055116915585019
The cells appeared irregularly arranged in interwoven and concentric bundles (Figure 4a,b); moderate infiltration of neutrophils, plasma cells and lymphocytes, and eight mitoses per HPF at x 10 magnification were observed.
Immunohistochemical staining with vimentin: note the diffuse positive staining of the cytoplasm (x 10)
10.1177_2055116915585019-fig5.jpg
PMC5362888_01_10.1177_2055116915585019-fig5.jpg
fig5-2055116915585019
Thermo Fisher Scientific), S-100 protein (Mouse S-100 Ab-1; Thermo Fisher Scientific), glial fibrillary acidic protein (rabbit antiglial fibrillar acidic protein, 1:500; Dako), smooth muscle actin (Perossidasi DAB detection; Dako) and desmin (Desmin Ab-2; Thermo Fisher Scientific). The neoplastic cells stained strongly positive for vimentin only (Figure 5).