Spindle cell carcinoma of the mandible: a case report

Spindle cell carcinoma is a rare highly malignant squamous cell carcinoma. Here, we describe a case of a 74-year-old Chinese female who presented with a 2-week history of pain and swelling in the left retromolar region. Surgical resection and titanium plate prosthesis were performed and histological analysis revealed spindle squamous cell carcinoma.


Introduction
Spindle cell carcinoma is a rare highly malignant squamous cell carcinoma. It is well accepted that this biphasic tumor is composed of squamous cell carcinoma (in situ or invasive) and sarcomatous spindle cell carcinoma. The latter has been described by various terms, including spindle cell squamous carcinoma, carcinosarcoma, pseudosarcoma, and pleomorphic carcinomal. We present a case of sarcomatous spindle cell carcinoma in a 74-year-old Chinese female who was managed by surgical resection and left mandible and titanium plate prosthesis.

Case report
A 74-year-old Chinese female patient was transferred to the Affiliated Stomatological Hospital of Nanjing Medical University with a 2-week history of pain and swelling in the left retromolar region. A poly-poid lesion measuring 20Â25 mm was observed. The patient had diabetes mellitus and hypertension. Her medical history also included wide surgical excision of an upper left gingival neoplasm, partial maxillect-omy and radical operation for the tongue, jaw and neck owing to upper left gingival squamous cell carcinoma and right tongue squamous cell carcinoma in February, 2005. The patient received radiotherapy with 60 Co, up to a total dose of 40 Gy, after surgery from March 21 to April 15, 2005, followed by further resec-tion to the left side of the tongue owing to tongue leu-koplakia on August 31, 2007 and enlarged resection of lower left periodontal lesions on account of gingival squamous cell carcinoma located at the left premolar area of the mandible in July 2010.
Intraoral examination indicated that the patient's teeth were all absent. In addition, a polypoid lesion measuring 20Â25 mm was noted in the front of the left pterygomandibular fold on the mandible, which was accompanied with pain on pressure (Fig. 1A). A part of the left maxilla was missing and the postoperative scar on the ventral area of the tongue had healed completely. Furthermore, adhesions were present on the tongue and mouth floor tissue and there was restricted movement without numbness. The extra-oral examination showed that although the patient's face was asymmetrical, the surgical scar on the center of the lower lip and chin, to the right of the jaw and neck had healed. On the trailing edge of the left mand-ible, a hard mass was palpable and was accompanied by mild pain. However, the overlying skin had a nor-mal appearance. No enlarged lymph nodes were palp-able in the submandibular triangle and neck.
An orthopantomogram radiograph revealed a lowdensity shadow in the left molar region (Fig. 1B). Computed tomography revealed that the maximum dimension of the lesion measured 3.863.2 cm. In addition, the margins were unclear, there was left mandibular osseous necrosis, and part of the left maxilla was missing (Fig. 1C). Given the poorly differentiated gingival squamous cell carcinoma, surgical resection and titanium plate prosthesis were performed (Fig. 1D).
Histologically, the bulk of the tumor was com-posed of proliferated spindle shaped cells, which were arranged in a fascicular pattern, or slice forma-tion. Some tumor cells showed an increasing mitotic activity as well as pleomorphism; there were also plasmacytoid and inflammatory cells, suggesting that this was a spindle cell lesion ( Fig. 2A). Immuno-histochemical analyses showed a positive staining for creatine kinase, vimentin and smooth muscle actin (SMA); weakly positive staining for CD99 and calpo-nin and negative staining for S-100, epithelial mem-brane protein (EMA), human melanoma black 45 (HMB45), CD31, CD34, MyoD1, desmin, actin, LCA, glial fibrillary acidic protein (GFAP) and Bcl-2, thereby confirming the diagnosis of spindle cell carcinoma ( Fig. 2B and 2C).
With the patient's history of gingival squamous cell carcinoma, this mandibular tumor was considered to be a recurrence and de-differentiation of the previous tumor because of its position near the previous tumor site. Based on the patient's medical history, her clinical presentation and positive results for creatine kinase and vimentin, we entertained a diagnosis of sarcomatoid carcinoma. The patient died after approximately five consent was obtained from the son of the patient for publication of this case report and any accompanying images.

Discussion
Sarcomatoid carcinoma is a type of malignant mixed tumor that is extremely rare in the mandible. The sarcomatous components are derived from the squa-mous epithelium with divergent mesenchymal differentiation [1] .
Spindle cell carcinoma most often affects elderly men, with a peak incidence in the sixth to seventh decade [2] . Reportedly, approximately 50% to 70% of head and neck spindle cell carcinoma presents as polypoid or exophytic lesions, sometimes with a stalk [3] . In this case, the lesion was polypoid, and the patient underwent radiotherapy with 60 Co up to a total dose of 40 Gy. It is possible that this could have led to spindle cell carcinoma of the mandible. The oral cavity is the most common primary site, followed by the larynx, oropharynx/ hypopharynx, maxilla and metastatic nodes [4] . This is the second detailed report in the English language literature of spindle cell carcinoma affecting the mandible.
The immunohistochemical study revealed that the cytokeratin positivity was significantly higher in spindle cell carcinoma than in the spindle cell and squamous cell components of spindle cell carcinoma. In addition, in comparison with the spindle cell component, the squa-mous cell areas of spindle cell carcinoma had a higher mean positivity for cytokeratin [5] ; the spindleshaped tumor cells were positive for vimentin but not for keratin and EMA. The results may indicate that these cells have acquired mesenchymal properties. Vimentin is the most common cytoskeletal marker for mesenchymal cells [6] . Reportedly, keratin expression decreases, whereas vimentin expression increases in the spindle cells of spindle cell carcinoma [7] . Immunostaining for pan-cytokeratin and EMA may be very useful; however, it is not uniformly positive for these tumors. Lewis et al. found that p63 staining was the most diagnostically useful tool, particularly in head and neck sarcomatoid carcinomas [4] .
Surgical excision was the widely preferred treatment and most authors agreed that irradiation was ineffective. There was no significant difference in the length of survival between patients managed by radiation alone and those managed by both radiation and a salvage procedure [8] . However, radiation therapy was considered to be an acceptable alternative for inoperable cases. In addition, adjuvant irradiation may benefit cases in which the surgical margins are positive or cases with nodal metastasis at the time of diagnosis [9] . Leventon et al. found that survival was related to the depth of invasion; patients with deeply invasive tumors had a low survival rate whereas those with superficial tumors had an excellent survival prognosis [2] . A low tumor stage and the absence of previous irradiation also indicate a better prognosis. Thompson reported that the survival rate of 39 patients with a negative immunohistochemical profile for epithelial markers was signifi- cantly higher than that of 84 patients with positive immunoreactivity for epithelial markers [8] .
Numerous hypotheses regarding the histogenesis of this type of tumor have been proposed. Three dominant pathogenetic theories have been proposed: (1) the tumor represents a 'collision tumor' (carcino-sarcoma); (2) the tumor is an squamous cell carcinoma with an atypical reactive stroma (pseudosarcoma) or (3) the tumor is of epithelial origin, with 'de-differentiation' or transformation to a spindle cell morphology (sarcomatoid carcinoma). In recent years, the third hypoth-esis has been supported by findings obtained using modern techniques, including electron microscopy and immunohistochemistry [10] .