PMC4860914_01
(a and b) Extraoral examination of left mandibular swelling that was firm to hard diffuse soft tissue swelling extending anteroposteriorly from midline to the left angle of the mandible and inferiorly extended 2 cm below the inferior border of the mandible. (c) Intraoral view showing the unilateral (left) involvement of the lesion
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F1
Extraoral clinical examination revealed a firm to hard diffuse soft tissue swelling measuring 4 cm x 5 cm that extended anteroposteriorly from midline to the left angle of the mandible and inferiorly extended 2 cm below the inferior border of the mandible [Figure 1a and b]. Intraorally, buccal cortical expansion was noted from midline to second molar region obliterating the vestibule with paresthesia of lower lip [Figure 1c].
(a) Cone beam computed tomography reconstructed panoramic image showing diffuse radiolucency in the left body of mandible extending superiorly to the alveolar crest and inferiorly to lower border; anteriorly to apex of 33 and posteriorly till the region of 36. (b) Cone beam computed tomography coronal section showing radiolucent lesion in the left body of mandible extending through buccal and lingual cortex, minimal mucosal thickening of the right and left maxillary sinus floor is seen. (c) Cone beam computed tomography sagittal section revealed radiolucency extending from 33 to 38 with erosion of the mandibular nerve canal. (d) Cone beam computed tomography axial section showing asymmetry on left side with loss of buccal and lingual cortical plates and no evidence of expansion of the cortical plates
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F2
Cone beam computed tomography (Planmeca ProMax  3D; Large FOV [200 mm x 100 mm]) imaging revealed an ill-defined, moth-eaten radiolucency in the left mandibular premolar/canine region with destruction of buccal and lingual cortical plates [Figure 2a-d].
(a) Gross surgical specimen showing the erosion and perforation of the buccal and lingual cortical plates. Cut surface of the tumor showing lingual invasion below the inferior border of mandible. (b): Photomicrograph showing presence of mixture of spindle- and round-shaped cells arranged in fascicles separated from normal epithelium by grenz zone (H&E stain, x40). (c) Photomicrograph showing tumor cells infiltrating the bone (H&E stain x40). (d): Photomicrograph showing round to spindle shaped tumor cells with hyperchromatic nuclei (H&E stain, x400)
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F3
Gross examination of the resected hemimandible showed attached lesional soft tissue measuring approximately "10.5 cm x 8.0 cm x 5.0 cm," white to brown in color, with multiple cystic spaces and no "crackling" upon palpation [Figure 3a]. Microscopic examination showed an encapsulated lesion situated in the connective tissue and separated from the overlying normal epithelium by a grenz zone [Figure 3b]. Morphologically, the neoplastic tissue showed a mixture of proliferating spindle-shaped cells arranged in fascicles and round cells infiltrating into the connective tissue stroma and bone [Figure 3c]. The neoplastic cells exhibited atypical features such as pleomorphism, hyperchromatism and increased mitotic figures with noncleaved nuclei [Figure 3d].
Round- and spindle-shaped tumor cells showing negativity for (a) desmin (IHC stain, x400); (b) smooth muscle actin (internal positive control; vessel wall) (IHC stain, x400); (c) S-100 (internal positive control; nerve) (IHC stain, x400), (d) CD1a (IHC stain, x400). The cells were positive for (e); leukocyte common antigen (lymphoid lineage marker) (IHC stain, x200); and (f) CD20 (B-cell marker) (IHC stain, x200)
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F4
Immunohistochemical staining with desmin [Figure 4a], smooth muscle actin (SMA) [Figure 4b], S-100 [Figure 4c] and CD1a [Figure 4d] were negative and lymphoid markers leukocyte common antigen (LCA) and CD20 (cluster differentiation marker for B-cells) showed positivity in spindle-shaped cells as well as round cells indicating the tumor to be a lymphoproliferative lesion of B-cell type [Figure 4e and f].