Pleomorphic Sarcoma of the Oral Cavity: A Rare Case Entity.

Pleomorphic sarcomas are extremely rare in the oral cavity, representing only 5% of all soft tissue sarcomas in the extremities of adults. They form a group of highly undifferentiated pleomorphic malignant tumors. A 36-year-old male reported to the OP with a chief complaint of a tooth ache in the right lower quadrant for the past 6 months. The patient gave a history of extraction of a mobile tooth in that region. A radiograph of the region was advised. An incisional biopsy was also done and sent for histopathological examination. The microscopy revealed the presence of spindle-shaped cells showing dysplastic features. A panel of immunohistochemical markers were performed to identify the tissue of origin of the lesion. The article details the clinical, radiographic, and microscopic features of a pleomorphic soft tissue lesion along with the array of immunohistochemical markers, leading to the final diagnosis of such enigmatic lesions. Copyright:

INTRODUCTION

12,000 new cases of adult sarcomas encompassing nearly 70 varied histological types such as fat, muscle, bone, blood vessels, and other mesenchymal tissues are being reported every year. Currently, the World Health Organization has classified the existence of undifferentiated pleomorphic sarcomas (UPS) that represent about 5% of all soft tissue sarcomas of the adults. These lesions are most commonly seen in the lower extremities of the human body as deep-seated tumors. They show heterogenicity in their microscopic appearance with no specific sense of an immunohistochemical (IHC) expression.[1] The occurrence of oral pleomorphic sarcoma is extremely rare, and this article highlights one such case with an emphasis on clinical, histopathological, and IHC analyses.

CASE REPORT

A 36-year-old male reported to the outpatient department with the chief complaint of tooth ache in the lower right posterior quadrant for the past 6 months. The patient also gave a history of extraction of a mobile tooth in that region. An orthopantomogram was advised for the patient that revealed the presence of a radiolucency involving the right second premolar (45) to the extracted socket of the second molar (47) [Figure 1]. An incisional biopsy was taken and sent for histopathological evaluation. The tissue was subjected to routine histopathological processing. A microscopic study revealed the presence of sheets of spindle-shaped cells with features of pleomorphism and mitosis [Figure 2]. An array of IHC markers were performed to arrive at a conclusive diagnosis. Vimentin for antigenicity, Pan-cytokeratin for epithelial tumors, S100 for neurological lesions, Myogenin for muscle tumors, and HMB 45 to rule out melanomas were performed. Of these, only a strong positivity for Vimentin was observed [Figure 3]. Further, IHC analysis using CD68 was done which showed focal positivity [Figure 4] and therefore the diagnosis of UPS was finally arrived at.

Figure 1

Orthopantomogram revealing radiolucency in the right second premolar region to the extracted socket of second molar

Figure 2

High-power view of incisional biopsy revealing sheets of spindle-shaped cells with features of dysplasia (H and E)

Figure 3

Scanner view showing intense positivity for Vimentin

Figure 4

Low-power view showing focal positivity for CD68

The patient was then treated with right hemimandibulectomy with elective lymph node dissection. The microscopic features of the excisional biopsy were similar to that of the incisional biopsy [Figure 5]. In addition, 9/10 mitotic figures per high-power field were observed with a Ki-67 labeling index of 65%–70%. A positron emission tomography/computed tomography scan revealed no distant metastases.

Figure 5

High-power view of the excisional biopsy showing features of pleomorphism and mitotic figures (H and E)

DISCUSSION

”Malignant fibrous histiocytoma” (MFH) was the term coined by Stout and Murray as the sarcoma cells had microscopic appearance similar to that of histiocytes that could also assume the shape of “fibroblast.”[2] A few pathologists suggested for a reclassification as the term was found to be confusing. This was undertaken in 2002 by the WHO, and as of now, the term “MFH” is no longer in use. It was replaced by the term UPS, which is still classified under the category of fibrohistiocytic tumors.[13]

Not more than 5% of UPSs are being reported among the various sarcomas these days.[4] To the best of our knowledge, not many oral UPSs have been reported in the English literature. According to Matushansky et al., two schools of thoughts exist for the etiopathogenesis of UPS, the first one being that the lesion represents a common pattern of morphology that is seen in many other tumors as a part of progression of the disease.[3] The second school of thought is along the lines of mesenchymal stem cell transformation.[45] Both these postulates need to be extensively researched for which many such cases of UPS need to be analyzed in detail.

Histopathological appearance of the tumor is not very consistent other than showing features of spindle-shaped cells appearing pleomorphic depicting abnormal mitosis. This poses some difficulty to the reporting pathologists. Several differential diagnoses need to be ruled out prior to the arrival of the conclusive diagnosis including spindle cell carcinoma, fibroblastic osteosarcoma, leiomyosarcoma, and on rare instances synovial sarcoma. An array of IHC markers including epithelial markers, neural markers, muscle tissue markers, and Vimentin help us in tissue typing.[4] In our case, only Vimentin showed strong possibility, which helped us rule out the other epithelial, neural, and muscle tumors. Keeping in mind the focal positivity for the histiocytic marker CD68 along with the high values in Ki-67 labeling index helped us clinch the final diagnosis of oral UPS.

In the present case, the patient did not have any distant metastases. Surgical management of the patient with hemimandibulectomy was performed and the patient was advised to undergo adjuvant radiotherapy, but the patient refused the same. The patient has been followed up for the past 2 years and no recurrence has been observed.

CONCLUSION

UPSs are extremely rare sarcomas occurring in the oral cavity. Multiple sampling of the biopsy specimen with prudent usage of IHC markers can help in the diagnosis of these lesions. Surgical management with adjuvant radiation therapy is the treatment of choice. An in-depth understanding of the molecular biology of these tumor cells is required for the diagnostic, prognostic, as well as theranostic purpose of this rare disease.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.