A Case of Spindle Cell Squamous Cell Carcinoma Manifesting in the Mandible Following Resection of Buccal Mucosal Squamous Cell Carcinoma

Abstract

Spindle cell squamous cell carcinoma (SCSCC) represents a distinctive subtype of squamous cell carcinoma, characterized by a marked malignancy and sarcomatoid transformations predominantly comprising spindle-shaped cells. In this context, we executed a surgical resection of a buccal mucosal squamous cell carcinoma, encompassing the mandibular periosteum, for a case where buccal mucosal cancer had pervaded the mandibular gingival mucosa. Notably, in a period of one year and four months subsequent to this procedure, a spindle cell squamous cell carcinoma emerged as an intraosseous carcinoma, originating from the periosteum resection. This report delineates the occurrence of this rare pathology. The subject of this case is an 83-year-old female. She underwent a resection of a buccal mucosal squamous cell carcinoma, including the mandibular gingival periosteum, for cancer on the right buccal mucosa. The histopathological evaluation post-surgery confirmed the diagnosis of squamous cell carcinoma with clear margins. A computed tomography (CT) scan, conducted one year and four months postoperatively, disclosed a contrast-enhanced tumorous growth in the mandible. Owing to the considerable restriction in opening caused by scarring and the attendant challenges in biopsy acquisition, an expedited intraoperative diagnosis was rendered. This preliminary assessment indicated a spindle cell sarcoma, leading to a hemimandibular resection. The final histopathological diagnosis was spindle cell squamous cell carcinoma. Twelve months have elapsed since the surgical intervention, with no evidence of recurrence or metastasis observed to date.

Keywords: buccal mucosal squamous cell carcinoma; intraosseous carcinoma; mandible; spindle cell squamous cell carcinoma; transformation.

Figure 1. Initial Intraoral Examination

A granular ulcerative lesion, measuring 17x15 mm, was observed extending from the right cheek mucosa to the mandibular gingival mucosa.

Figure 2. Panoramic X-Ray

The panoramic X-ray images displayed no abnormal findings.

Figure 3. CT Scan

Absence of lesions in the right buccal mucosa and no evidence of bone resorption due to tumor. No abnormalities in the neck or distant organs.

Figure 4. MRI

Gadolinium-enhanced fat-suppressed T1-weighted images revealed a mass lesion in the right buccal mucosa with contrast enhancement.

Figure 5. PET-CT

Significant uptake noted in the primary tumor, with no suspicious accumulations in cervical lymph nodes or elsewhere in the body.

Figure 6. Histopathological Findings at the Time of Initial Surgery (Hematoxylin and Eosin Staining)

Polygonal squamous cell carcinoma cells were identified. The tumor exhibited superficial invasion into the interstitium, with no infiltration into the deeper tissues. Neither lymphatic nor vascular invasion was observed.

Figure 7. Follow-up Findings

No recurrence was observed in the oral cavity.

Figure 8. CT scan

A large, contrast-enhanced lesion was observed in the right mandible, with cortical bone destruction evident on both the buccal and lingual aspects. No abnormalities were noted in the neck or distant organs.

Figure 9. Panoramic X-ray

Panoramic X-Ray in the Event of Recurrence or New Lesion A radiolucent lesion, approximately 32x25 mm in size, was observed in the body of the right mandible.

Figure 10. MRI

Gadolinium-enhanced fat-suppressed T1-weighted imaging of the right mandible revealed a large lesion with contrast enhancement.

Figure 11. Surgical resection specimen findings in the event of recurrence or new lesion

The resection was performed with a margin of at least 10 mm from the tumor, encompassing the submandibular gland, mylohyoid muscle, and sublingual gland on the lingual side, and the masseter and buccinator muscles on the buccal side, to account for potential extra-mandibular invasion.

Figure 12. Histopathological findings (Hematoxylin and Eosin staining)

Interstitial fibrosis was observed just below the epithelium, with atypical spindle cells present within this region. Furthermore, proliferation of spindle-shaped cells was noted in the mandibular bone, leading to trabecular destruction.

Figure 13. Histopathological findings (Cytokeratin AE1/AE3)

Cytokeratin AE1/AE3 exhibited positive staining.

Figure 14. Histopathological findings (Vimentin)

Vimentin showed positive staining.