Clinical Profile:

A 55 year old woman presented with swelling and pain in the left jaw since three months.

She also complained of paraesthesia over the left lower lip since one month.

She is a known chronic gutka chewer.

There was no history of any similar complaints in the past.

Radiological findings

The plain radiograph of the mandible shows a soft tissue swelling in the region of the left mandible.

There is an ill defined radiolucency seen in the region of the left angle of mandible. The overlying cortex is thinned out.

On sonographic examination, the left hemimandible shows a well defined, expansile. smooth soft tissue lesion arising from the 'marrow' space adjacent to the angle of the mandible.

The lesion is hypoechoic with mild surrounding spiculated periosteal reaction .

There is a breach in the outer cortex of the mandible. The soft tissue appears to be extending externally through the breach in the cortex.

The soft tissue mass seen in the left hemimandible shows vascularity on colour Doppler imaging .

On CT examination, the lesion is seen to extend into the adjacent buccal space .The lesion shows mild enhancement.

These findings were suggestive of a neoplastic lesion.

On the PET scan there is a hypermetabolic, destructive lesion in left body of the mandible in keeping with a malignant etiology.

A metabolically active left level II node is also seen.

Final diagnosis :

Solitary bone plasmacytoma of the left hemimandible.

Treatment:

The patient is currently undergoing radiotherapy for the same . The option of surgery and radiotherapy were discussed with the patient. Patient opted to undergo radiotherapy alone. She is currently improving symptomatically with reduction in pain at local site and reduction in the size of the swelling.

Discussion:

Solitary plasmacytoma is most frequently seen in vertebrae andsecondarily in long bones. Its presence in jaws is extremely rare.

Plasmacytoma is a neoplastic proliferation of plasma cells. It is one formof plasma cell dyscrasia that may manifest as multiple myeloma, primary amyloidosis, or monoclonal gammopathy of unknown significance.

Plasmacytoma may be primary or secondary to disseminated multiple myeloma and may arise from osseous (medullary) or nonosseous (extramedullary) sites.

Primary plasmacytoma can be solitary or multiple.

Radiography and CT :

Solitary plasmacytoma of bone may appear as a lytic lesion or as an area of bone expansion with thinning and destruction of the overlying cortex and a "bubbly" or trabeculated appearance. The margins are usually well defined, sharply demarcated and characteristically without a sclerotic reaction.

Differential diagnosis include - chronic osteomyelitis, osteolytic metastasis, osteoid osteoma, osteoblastoma, inclusion cyst brown tumor of hyperparathyroid, ABC and benign giant cell tumour A solitary bone plasmacytoma arises from the plasma cells located in the bone marrow, whereas extramedullary plasmacytoma is thought to arise from plasma cells located in mucosal surfaces. Both represent a different group of neoplasms in terms of location, tumor progression, and overall survival rate. Both do, however, share many of the biologic features of other plasma cell disorders.

CT may demonstrate subtle lytic lesions or small soft-tissue masses, particularly of the sternum, that are not visible at radiography.

Prognostic factors:

Age of the patient ( Older the patient , poorer the prognosis)

Size of the lesion: Plasmacytoma > 5 cm indicates a poor prognosis

Persistence of M protein following radiotherapy indicates a poor prognosis

Low polyclonal immunoglobulins (also raises concern for myeloma)

Osteopenia

Treatment Options:

Medical options::

Local radiotherapy is the treatment of choice for solitary bone plasmacytoma (SBP). Treatment fields should be designed to encompass all disease observed and should include a margin of healthy

tissue (at least 2 cm). For spinal lesions, the margins should include at least 1 uninvolved vertebra.

Most centers use approximately 40 Gy for spinal lesions and 45 Gy for other bone lesions. For lesions larger than 5 cm, 50 Gy should be considered.

Other options:

Surgery is contraindicated in the absence of structural instability or neurologic compromise.

Chemotherapy may be considered for patients not responding to radiation therapy. Regimens useful in multiple myeloma can be considered. No role exists for adjuvant chemotherapy in Solitary Plasmacytoma.

When a lesion can be completely resected, surgery provides the same results as radiotherapy.

Combined therapy (surgery and radiotherapy) is an accepted treatment depending on the resectability of the lesion. In fact, combination treatment may provide the best results. The optimal radiation dose for local control is 40-50 Gy (depending on tumor size) delivered over 4-6 weeks.

Because of the high rate of lymph node involvement, local nodess should be included in the radiation field.

Adjuvant radiotherapy should be recommended to patients with positive surgical margins.

References:

1. Christopherson WM, Miller AJ. A re-evaluation of solitary plasma-cell myeloma of bone. Cancer. 1950;3:240–51.

2. Kanazawa H, Shoji A, Yokoe H, Midorikawa S, Takamiya Y, Sato K. Solitary plasmacytoma of the mandible. Case report and review of the literature. J Craniomaxillofac Surg. 1993;21:202–6.

3. Loh HS. A retrospective evaluation of 23 reported cases of solitary plasmacytoma of the mandible, with an additional case report. Br J Oral Maxillofac Surg. 1984; 22:216–24.

4. Pisano JJ, Coupland R, Chen SY, Miller AS. Plasmacytoma of the oral cavity and jaws: A clinicopathologic study of 13 cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 1997;83:265–71.

5. Gray ST, Antunovic DM, White AE. Non secretory multiple myeloma involving the maxilla: Report of a case with update of biology and new approaches to management. Oral Oncol. 1997;33:136–40.

6. Kanthan R, Torkian B. Solitary plasmacytoma of the parotid gland with crystalline inclusions: A case report. World J Surg Oncol. 2003;1:12.

Acknowledgement:

I am grteful to Dr. Ishita Dutta from the Department of Pathology for providing the histopathology image and description of the histological examination.