Hemangiopericytoma of the gingiva - An exemplary differential of a masquerading tumor.

Periodontal diseases are unique as a small number lesions appearing as inflammatory in reality are neoplastic in nature, and it is imperative that an accurate diagnosis be rendered to provide the appropriate treatment and management. One of the most common clinical presentations of gingival lesions is pedunculated soft-tissue swellings. We report the case of a 63-year-old female who presented with a painless swelling on the interdental papilla of 23 and 24 with a history of recurrences. The lesion was excised by wide surgical excision. This article presents a unique case of a vascular tumor that had clinically mimicked a reactive lesion and with detailed history, thorough clinical examination had provided clues to a vascular entity namely hemangiopericytoma which was confirmed by histological diagnosis. Oral lesions, particularly occurring in gingiva, most often appear clinically benign or innocuous thus necessitating the need for careful examination with investigations to render a diagnosis. Copyright:

INTRODUCTION

Periodontal disease can be challenging even to specialists of periodontics in rendering a diagnosis and providing appropriate treatment, especially with lesions clinically appearing as reactive lesions but in fact are neoplastic in nature.[12] A thorough history and clinical examination are required to rule out by exclusion the obvious lesions. In this article, we present a case that on first look appeared as an innocuous reactive lesion around the dentogingival junction but correlating with the clinical, radiological, and histological features revealed the lesion to be a vascular tumor namely hemangiopericytoma.

CASE REPORT

A 62-year-old female patient reported with a soft-tissue swelling in the interdental papillae in relation to 23 and 24 for the past 3 weeks. History revealed similar occurrences, specifically twice in the same site in a span of 1 year for which, at both times, the dentists she had visited had performed an excisional biopsy which the patient had not followed up for the biopsy report.

On clinical examination, the surface of the swelling was erythematous along the periphery which gradually showed a bluish color toward the center. The swelling was irregular in shape with a shiny but pebbly surface. The swelling was 1 cm × 1.5 cm and was nontender and did not show spontaneous bleeding. The swelling extended beyond the gingival margin and bleeding was observed on probing using William's probe [Figure 1]. Intraoral radiograph had shown radiolucency in the interdental region of 23 and 24 [Figure 2]. An excisional biopsy was performed that had led to continuous bleeding that ceased in around 20 min. A periodontal dressing was applied and the patient was asked to report after 14 days for review [Figure 3]. A provisional diagnosis of pyogenic granuloma, in spite of recurrence, was ruled out as the patient had maintained good oral hygiene and history had revealed that oral prophylaxis was also performed by the dentists as part of treatment for suspected pyogenic granuloma. Considering the history and the clinical features, a provisional diagnosis of the vascular tumor was rendered. The excised specimen was sent for the histopathological diagnosis.

Figure 1

Soft-tissue swelling in interdental papilla of 23 and 24

Figure 2

Radiolucency in relation to the interdental region of 23 and 24

Figure 3

Postoperative photograph: Immediate (a), after 2 weeks (b) after 3 months (c)

The histopathology of the lesion had shown the presence of highly cellular tumor within the connective tissue with a thin overlying oral mucosal epithelial lining. Low power magnification showed these tumor islands to be proliferating within a bland connective tissue devoid of inflammatory cells [Figure 4a and b]. The tumor did not show the presence of any capsule. Higher magnification revealed tumor cells that were spindle-shaped similar to the morphology of fibroblast and were closely associated with vascular channels which exhibited the distinct Staghorn appearance. The nucleus of these spindle-shaped cells was vesicular without any mitotic figures [Figure 4c].

Figure 4

Photomicrograph showing parakeratinized stratified squamous surface epithelium and underlying highly cellular stroma showing numerous proliferating plump and spindle shaped tumor cells with vesicular nuclei (blue arrow) and some vascular spaces in staghorn pattern (a) H and E, ×4, (b) H and E,×20 (c) H and E,×40

Correlating the history and clinical features, with the histological features seen in the present case, a final diagnosis of hemangiopericytoma was made.

DISCUSSION

Hemangiopericytoma is a tumor of the pericytes that surround the blood vessels and provide structural support to vessel walls. The close spatial relation with endothelial cells plays a key role in maintaining the integrity of the vessels and sustaining circulatory homeostasis. Apart from the above-mentioned functions, these cells help in endothelial cell differentiation and in the process of angiogenesis in repairing or restoring microcirculation to the remotest areas of the body such as the periodontal ligament to ensure continuous blood supply.[12]

Literature of these tumors in the English literature has shown that cases of hemangiopericytomas arising in the oral cavity are rare and the behavior of these tumors are aggressive that is evident due to recurrences in spite of performing deep excisional biopsy to completely remove the tumor cells. It is this aggressiveness by which surgeons and authors usually refer to them as malignant rather than a benign entity.[345] Furthermore, the classifications of soft-tissue tumors can be most challenging and undergo several revisions due the history of recurrences, diverse histology pattern, differentiation and immunohistochemical genetic profile, particularly hemangiopericytomas, which were removed from the soft-tissue classification in 2013 and were considered as solitary fibrous tumor due to NAB2-STAT6 gene fusion in both the tumors.[12] However, these tumors were then merged as solitary fibrous tumor/hemangiopericytoma in the revised soft-tissue classification given by the World Health Organization in 2016.[2] The cause of hemagiopericytomas is unknown and in the oral cavity, these lesions are seen to occur in the second to seventh decade and no gender predilection with an incidence of 16% to 25%.[6] The histological appearance of spindle cell morphology in these tumors can appear as an extension or differentiation of a fibroblastic tissue; however, the presence of vascular channels and a close approximation of tumor cells to the vessels cannot delineate the histiogenesis of these tumors and is the reason for debate in the christening of such tumors. A consistent IHC marker used for the diagnosis is the CD34 and bcl-2, as well as the recent STAT6 which has shown strong nuclear reactivity. The definition of malignant hemangiopericytoma is controversial and histological features such as immature tumor cells, necrosis, high mitotic index, and metastasis have been proposed as indicators of malignancy.[78] In the present case, the tightly packed proliferation of tumor cells was seen in close vicinity, maybe even originating from the lining, of blood vessels of varying diameters. The distinct spindle cell morphology with the vesicular nucleus was observed was consistently seen all throughout the slide. Another feature absent was inflammatory cells that are seen in reactive lesions such as pyogenic granulomas. The presence of an intact overlying epithelium is another characteristic feature absent in histology of pyogenic granulomas.

Clinical differential diagnosis of such lesions includes inflammatory hyperplasia such as pyogenic granuloma, fibrous hyperplasia or fibroma, and peripheral giant cell granuloma. Among the most common and frequently encountered lesion is the pyogenic granuloma which in the present case appeared similar clinically; however, in spite of performing oral prophylaxis and multiple excisional biopsies, the patient had given a history of recurrences which is observed in these tumors.[91011] Bleeding is another clinical feature observed in the present case commonly seen in peripheral giant cell granulomas; however, these lesions tend to appear more blue-purple than red, with cupping resorption in radiographs, low recurrence rate with removal of the inciting factors which were absent in the present case. The aggressiveness of this tumor can be comprehended by reviewing literature with in case reports of hemangiopericytomas recurring as well as occurring simultaneously in the soft palate and mediastinum.[12] Another feature observed during the clinical examination suggestive of a vascular entity was the continuous bleeding that occurred on elevating the lesion and controlling the bleeding after excisional biopsy. The erythematous periphery and bluish central discoloration could also be seen in large pyogenic granulomas but concurrently with the presence of the inflammation inciting plaque and calculus in the gingival sulcus which was not evident in the present case. A further finding was the radiolucency of alveolar bone in relation to the interdental region of 23 and 24 which are not observed in reactive lesions.

The treatment and prognosis of hemangiopericytoma are dependent on the amount of cellularity and the presence of mitotic activity in the tumor cells. Although the tumor has shown resistance to the treatments performed surgically, wide local surgical excisional usually suffice in low cellular lesions and tumors expressing high cellularity, dysplasia, and mitotic activity require radical dissection with radiotherapy.[10131415] These tumors do recur but rarely metastasize. In the present case, the probable reason for recurrence could be incomplete removal of the lesion in the prior biopsies. The histopathology had shown a highly cellular connective with tumor cells devoid of any dysplastic features. Given the benign nature and history of recurrence, a wide dissection was performed and the patient is being reviewed every 3 months.

CONCLUSION

Hemangiopericytomas are soft-tissue tumors that are aggressive and require similar aggressive treatment and long-term follow-up. The present case is one example of the vascular tumor and hemangiopericytoma that can mimic reactive lesions frequently seen in the gingiva and misdiagnosed clinically. History with thorough clinical examination can provide “clinical” clues to the biological behavior or nature of the tumor and prevent an inadvertent misdiagnosis. Histiopathological examination remains the gold standard to establish an accurate diagnosis.

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.

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Conflicts of interest

There are no conflicts of interest.