PMC10359685_01
A preoperative MRI scan of case 1. MRI scans showing a well-defined and regular tumor in the right parotid gland (a-c). Axial T1-weighted (a) and T2-weighted (b) images of the mass showing hypointense and hyperintense signal intensities, respectively. c A hyperintense signal in the mass is visible on the coronal STIR image. Arrowheads indicate the tumor mass. MRI, magnetic resonance imaging; STIR, short TI inversion recovery.
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F1
Magnetic resonance imaging (MRI) scan revealed a well-circumscribed regular mass of 32 x 30 x 24 mm in the right parotid gland (Fig. 1).
Histological findings of case 1. a The gross resected specimen is a grayish-white hard tumor. b The tumor is surrounded by adipose tissue, including salivary glands, according to H/E staining (black arrows). The tumor is composed of stellate and spindle-shaped cells proliferating with a branching vascular network (b, c). c Mitosis is observed (white arrow). Immunohistochemical staining shows that neoplastic cells are positive for CD34 (d) and STAT6 (e). Scale bars, 1 mm (b); 50 mum (c); and 100 mum (d, e). H/E, hematoxylin and eosin.
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F2
Notably, the gross resected specimen was a grayish-white solid tumor (Fig. 2a). Histopathological examination revealed that the tumor was extensively vitiated and comprised stellate and spindle-shaped cells proliferating with a branching vascular network (Fig. 2b, c). The surrounding salivary gland tissue was also observed (Fig. 2b). Immunohistochemical staining revealed that the neoplastic cells were negative for AE1/AE3, alpha-SMA, p63, and S100 protein but positive for CD34, vimentin, Bcl2, and STAT6 (Fig. 2d, e).
PMC10359685_02
A preoperative MRI scan of case 2. MRI scan showing a well-defined regular mass in the right buccal region (a-c). Axial T1-weighted (a) and T2-weighted (b) images of the mass showing pale hyperintense and heterogeneous hyperintense signal intensities, respectively. c Coronal STIR image shows a heterogeneous hyperintense signal in the mass. Arrowheads indicate the tumor mass. MRI, magnetic resonance imaging; STIR, short TI inversion recovery.
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F3
MRI scan revealed a well-defined regular mass of 40 x 36 x 31 mm in the right buccal space (Fig. 3).
Cytomorphology of fine needle aspiration. Smear showing multilayered clusters of oval- to spindle-shaped nuclei. Pleomorphic adenoma - a type of myoepithelial tumor - is suspected. Papanicolaou stain. Scale bar, 50 mum.
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F4
Based on the findings of fine needle aspiration cytology, a tumor derived from myoepithelial cells of the minor salivary gland (e.g., pleomorphic adenoma) was suspected; however, it was difficult to distinguish the tumor from a nonepithelial tumor (Fig. 4).
Histological findings of case 2. a The gross resected specimen is a yellow-white tumor. b H/E staining showing muscles surrounding the tumor (black arrows). Spindle cells with rod-shaped or irregular nuclei and densely hyalinized collagenous stroma can be seen (b, c). c Mitosis is observed (white arrows). Immunohistochemical staining shows that neoplastic cells are positive for CD34 (d) and STAT6 (e). Scale bars, 500 mum (b) and 50 mum (c-e). H/E, hematoxylin and eosin.
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F5
The gross resected specimen was a yellow-white tumor (Fig. 5a). Histopathological examination revealed that the tumor comprised spindle-shaped cells with rod-shaped or irregular nuclei and a densely hyalinized collagenous stroma (Fig. 5b, c). The surrounding tissue, including a few muscles, was observed; conversely, normal salivary gland tissue was not observed (Fig. 5b). Immunohistochemical staining revealed that the neoplastic cells were negative for AE1/AE3, alpha-SMA, p63, calponin, and S100 protein but positive for CD34, CD99, Bcl2, and STAT6 (Fig. 5d, e).