case_images: PMC7550938_01
case_images: Microscopic findings of the tumor resected 5 years previously, and an MRI scan and
  macroscopic findings of the recurrent tumor. (a) A low-power view of the tumor revealed
  a poorly circumscribed lesion. Bar = 1.0 mm (H&E staining; original magnification: x
  12.5). (b) The tumor showed a fascicular pattern with moderate cellularity. Bar = 200 mum
  (H&E staining; original magnification: x 100). (c) The tumor was composed of spindle
  cells with mild to moderate nuclear atypia. Bar = 50.0 mum (H&E staining; original
  magnification: x 400). (d) The tumor cells were considered to be reactive for nuclear
  beta-catenin. Bar = 50.0 mum (original magnification: x 400). (e) Enhanced T1-weighted MRI
  showed a 43 mm tumor in the left nasal cavity. The orbit adjacent to the tumor was
  slightly unclear. (f) The tumor tissue resected from the nasal cavity, weighed 16 g (in
  total) and had a tan color.
case_images: 10.1177_2050313X20964090-fig1.jpg
case_images: PMC7550938_01_10.1177_2050313X20964090-fig1.jpg
case_images: fig1-2050313X20964090
case_images: A microscopic study of the tumor revealed a poorly circumscribed lesion (Figure 1(a)). The tumor showed a fascicular fashion with moderate cellularity (Figure 1(b)). The tumor was composed of spindle cells with mild to moderate nuclear atypia (Figure 1(c)). They were considered to be reactive for nuclear beta-catenin (Figure 1(d)) and negative for desmin. Magnetic resonance imaging (MRI) revealed a 43 mm tumor in the left nasal cavity with suggestion of orbit involvement (Figure 1(e)). Recurrence of the desmoid-type fibromatosis was clinically considered, and the tumor was surgically removed, weighing 16 g in total and showing a tan-colored cut surface (Figure 1(f)).
case_images: Microscopic and immunohistochemical findings of the recurrent tumor. (a) A low-power
  view showed a poorly circumscribed lesion intermingled with hemorrhage. Bar = 1.0 mm
  (H&E staining; original magnification: x12.5). (b) The tumor showed a fascicular
  growth pattern with high cellularity. Bar = 200 mum (H&E staining; original
  magnification: x100). (c) The tumor was predominantly composed of atypical spindle cells
  with elongated nuclei and scant cytoplasm. Bar = 50.0 mum (H&E staining; original
  magnification: x400). (d) Scattered eosinophilic rhabdomyoblasts were present.
  Bar = 50.0 mum (H&E staining; original magnification: x400). (e) A high-power view of
  tumor cells with cross-striations. Bar = 20.0 mum (H&E staining; original
  magnification: x1000). ((f)-(h)) The tumor cells were not reactive for (f) nuclear
  beta-catenin but were positive for (g) myogenin and (h) MyoD1. Bar = 50.0 mum (original
  magnification: x400). (i) The tumor was positive for H3K27me3. Bar = 50.0 mum (original
  magnification: x400).
case_images: 10.1177_2050313X20964090-fig2.jpg
case_images: PMC7550938_01_10.1177_2050313X20964090-fig2.jpg
case_images: fig2-2050313X20964090
case_images: Microscopically, the lesion was poorly circumscribed and intermingled with hemorrhage (Figure 2(a)). The tumor displayed a fascicular growth pattern with high cellularity and was predominantly composed of atypical spindle cells with elongated nuclei and scant cytoplasm (Figure 2(b) and (c)). In addition, scattered eosinophilic rhabdomyoblasts and cross-striations in the tumor cells were present (Figure 2(d) and (e)). Immunohistochemistry revealed that the tumor cells were not reactive for nuclear beta-catenin (Figure 2(f)) but were positive for myogenin (Figure 2(g)), myoglobin, desmin, MyoD1 (Figure 2(h)), alpha-SMA, HHF-35, cytokeratin CAM5.2, and epithelial membrane antigen (EMA).