Plasma cell granuloma of gingiva.

Plasma cell granuloma is a rare benign lesion characterized by the infiltration of plasma cells; primarily occurring in the lungs. It is also seen to occur in the brain, kidney stomach, heart, and so on. In the intraoral region it is seen to involve the tongue, oral mucosa, and gingiva. This case presents a 42-year-old female, with an enlargement in the maxillary anterior region, treated by excisional biopsy. Histological evaluation revealed plasma cell infiltrates in the connective tissue. The immunohistochemistry revealed kappa and lambda light chains with a polyclonal staining pattern, which confirmed the diagnosis of plasma cell granuloma.

INTRODUCTION

Plasma cell granuloma, otherwise known as an inflammatory pseudotumor is an uncommon non-neoplastic lesion considered to be the result of an inflammatory condition. Plasma cell granuloma is very rare in the oral cavity, and more so, on the gingiva. These lesions have no sex predilection and may occur at any age. Plasma cell granuloma has been called by different terms, namely; Inflammatory myofibroblastic tumor, Inflammatory pseudotumor, Inflammatory myofibrohistiocytic proliferation, and Xanthomatous pseudotumor.[1]

Although it is an uncommon lesion, when it occurs it is commonly seen in the lungs[2] and some other anatomic locations such as brain,[3] kidney,[4] stomach,[5] heart,[6] and so on. In the head and neck region it has been reported in the oral mucosa,[7] temporal bone,[8] tonsil,[9] sub-mandibular region,[10] paranasal sinuses,[11] tongue,[12] and on the gingiva[13-17].

The exact incidence of plasma cell granuloma is unclear. The lesion's etiopathogenesis, biological behavior, and appropriate treatments are unclear, and little is known about the prognosis. It may arise due to periodontitis, periradicular inflammation due to the presence of a foreign body or may be due to an idiopathic antigenic cue. The most commonly considered treatment for plasma cell granuloma is a complete resection; however, in some cases, total surgical excision is not possible.[1]

CASE REPORT

A 42-year-old Indian female patient reported to the Department of Periodontics, Pacific Dental College and Hospital with a gingival enlargement in the right upper anterior region between the lateral incisor and the canine. The enlargement was oval in shape and measured around 1.5 cm in diameter. It was firm, lobulated, and attached to the gingiva by a narrow stalk [Figure 1]. The patient complained of the enlargement interfering with the oral hygiene procedures and was bleeding on brushing. The patient presented no other relevant medical history.

Figure 1

Gingival enlargement in the right upper anterior region between the lateral incisor and the canine

A complete hemogram was done and all the values were within normal limits. The radiological examination of the region showed no bony involvement [Figure 2].

Figure 2

Intraoral, periapical radiograph of the region showing no bony involvement

An excisional biopsy and gingivoplasty was performed under local anesthesia and the specimen was sent for histopathological examination. The healing was uneventful.

The histopathological examination, with Hemotoxylin and Eosin stain, revealed a stratified squamous parakeratinized hyperplastic epithelium, with underlying fibrocellular connective tissue stroma [Figure 3], with fibroblasts, few lymphocytes, and abundant plasma cells [Figure 4]. However, a typical eccentrically placed hyperchromatic, cartwheel-shaped nucleus of the plasma cell was also evident [Figure 5]. The histopathological appearance, when co-related with the clinical features, was suggestive of plasma cell granuloma of the gingiva. Immunohistochemical staining for kappa and lambda light chains was carried out, to check for the presence of plasma cells. A strong positivity for the kappa light chain was seen in the polyclonal plasma cell population [Figure 6], whereas, a weak expression was noted for the lambda light chain [Figure 7], with a ratio of 2:1. A polarized microscopic study was also carried out, but failed to reveal any birefringence.

Figure 3

Micrograph at low magnification showing plasma cell infiltrate and elongated rete ridges

Figure 4

Low power microscopy showing abundant plasma cells in the connective tissue

Figure 5

High power microscopy showing plasma cells with eccentrically placed nucleus

Figure 6

Immunohistochemistry for kappa chains

Figure 7

Immunohistochemistry for lambda chains

DISCUSSION

During the late 1960s and early 1970s, cases of plasma cell infiltrates of the lips, gums, and tongue were described primarily in the dental literature under the names of atypical gingivistomatitis, idiopathic gingivistomatits, and allergic gingivostomatitis. The lesions were thought to be a result of a reaction to chewing gum, dentrifices, and other foreign substances, although extensive allergy testing had been inconclusive.[1]

Tumors that are mainly composed of plasma cells may be multiple myeloma, solitary myeloma, soft tissue myeloma (plasmacytoma), or plasma cell granuloma. Multiple myeloma and solitary myeloma are tumors of the bone, whereas, plasmacytoma and plasma cell granuloma are soft tissue tumors. Differentiating the type of soft tissue tumor is mandatory, as plasma cell granuloma may be benign, but plasmacytoma may show early stages of multiple myeloma.[13]

Plasmacytoma is a well-defined locally destructive lesion, located on the mucosa of the oropharyngeal region, which may be singular like plasma cell granuloma. Histologically, they have typical and atypical plasma cells, unlike plasma cell granuloma, which consists of normal plasma cells and small lymphocytes that are surrounded by connective tissue septa, Rusell Fuchs bodies.[8]

The immunohistochemistry determines the clonality of the lesion, where, in a reactive lesion, the kappa to lambda light chain ratio is 2:1, and in the case of malignancy the ratio may be greater than 10:1 or 1:10.[14]

The pathogenesis of the plasma cell granuloma remains unclear. The large number of plasma cells may represent an autoimmune reaction or an alteration of blood flow imposing congestive vasodilation.[7] Lesions occurring due to parasitic infiltration can also not be ruled out.[12]

CONCLUSION

Plasma cell granuloma is a lesion that is diagnosed primarily based on histological findings. The etiology remains unclear, but it is thought to aris due to a non-specific inflammatory response to an unknown exogenous agent.

This case report reinforces the existence of plasma cell granuloma on the gingiva and the need for submitting all the excised gingival tissue for microscopic examination, irrespective of the clinical features and clinical diagnosis.