Multiple myeloma involving mandible: In an elderly female.

Multiple myeloma (MM) is a malignancy of plasma cell origin. It often has a multicentric origin within the bone. It makes about 1% of all malignancies and 15% of all hematologic malignancies. There is a monoclonal proliferation of abnormal plasma cells in this disease that arise from a single malignant precursor that has undergone uncontrolled mitotic division. These cells in turn produce one type of immunoglobulin light chain, either kappa or lambda. Unifocal, monoclonal proliferation of plasma cells is called plasmacytoma. Hereby, we present a case of a 65-year-old female patient who presented with a swelling of the mandible. The uniform sheets of plasma cells in the histopathology punched out radiolucencies in skull radiograph and the blood picture of anemia and hypercalcemia, confirmed the case as MM.

Multiple myeloma (MM) otherwise called as plasma cell myeloma, myelomatosis or Kahler's disease are plasma cell neoplasm derived from bone marrow stem cells of B-cell lineage resulting in monoclonal proliferation of immunoglobulin light chain of either kappa or lambda type. Abnormal plasma cells accumulate in the bone marrow, which inhibit the production of other normal blood cells. It can be diagnosed by bone marrow examination, serum protein electrophoresis, serum-free kappa/lambda light chain assay, urine protein electrophoresis, and radiographs of involved bones.

Hereby, we present a case, which was clinically diagnosed as odontogenic tumor as the presenting clinical features were pain and swelling in the lateral aspect of the mandible. Uniform sheets of plasma cells and amyloid-like deposits in the histopathology made it a diagnostically challenging case. More interestingly, differentiating MM from plasmacytoma, which has the same histopathological feature, was possible by correlating with the skull radiograph and blood picture.

Case Report

A 65-year-old female patient presented with a swelling in the right ramus region for past 3 months. On intraoral examination, generalized destructive periodontitis and few carious teeth were noticed. She did not have any other relevant medical history or habits. Orthopantomograph (OPG) of the mandible showed a moth-eaten type of radiolucency.

Investigations

An incisional biopsy was performed, and the specimen was sent for histopathological examination. The hematoxylin and eosin stained sections of the specimen under the microscope showed a highly cellular connective tissue stroma. The lesional tissue comprised diffuse, monotonous sheets of neoplastic, plasmacytoid cells with perinuclear halo [Figures 1 and 2]. Uniform background of eosinophilic area suggestive of amyloid deposits were also observed showing positivity for Congo red stain [Figure 3]. The lesion was diagnosed provisionally as plasma cell neoplasm, but to know whether it was unifocal or multicentric to give diagnosis of plasmacytoma or MM, respectively, we sent the patient for skull radiograph and other relevant blood investigations. It was observed that the patient was anemic with Hb count of 7 g/dl and the serum calcium level was also raised. Urine test showed elevated Bence-Jones protein of 0.10 g. Multiple punched out radiolucencies were seen in the skull radiograph [Figures 4 and 5]. On account of these features, the case was finally diagnosed as MM.

Figure 1

H and E stained section showing monoclonal plasma cells ×10

Figure 2

H and E stained section showing sheets of malignant plasma cells with eccentric nuclei ×40

Figure 3

Congo red stained section showing positivity for amyloid

Figure 4

Skull radiograph posterior-anterior view showing multiple punched out radiolucencies

Figure 5

Skull radiograph lateral view showing multiple punched out radiolucencies

Differential diagnosis

The swelling in the mandible and the radiolucency in OPG made us to give a clinical diagnosis of the odontogenic tumor. A differential diagnosis of eosinophilic granuloma, plasmacytoma, MM, lymphoma or Langerhans cell histiocytosis was made considering the mononuclear infiltrate in the histopathological section.

Discussion

Multiple myeloma (MM) is a malignancy of plasma cell origin It accounts for about 1% of all malignancies and 15% of all hematologic malignancies.[1] There is a monoclonal proliferation of abnormal plasma cells in this disease, often multicentric within the bone. Unifocal, monoclonal proliferation of plasma cells is called plasmacytoma.[2]

Multiple myeloma is a disease of the elderly male population, with a median age of approximately 70 years, at manifestation. Our case was a female patient aged 65 years. MM is characterized by monoclonal proliferation of plasma cells and their products, immunoglobulins.[34] Median survival time is 5–7 years in patients treated with high-dose chemotherapy and autologous transplantation and 3–4 years in patients treated with conventional chemotherapy.[5] Increase in volume and pain on the affected site are the most common clinical presentation of this disease. The presence of paresthesia, dental mobility, hemorrhage, and pathological fractures include other features.[678] Radiographic assessment of the jaws of an MM patient usually shows three different types of presentations: Generalized rarefaction, multiple radiolucent areas or on occasion, there may be the absence of bony abnormality.[89] Studies report that MM appear as an osteolytic lesion with diffuse and ill-defined borders in few cases and in most of the reported lesions, the borders are well demarcated with “multiple punched out radiolucencies.”[89] Our case also showed the same radiological feature.

The microscopic appearance of MM is highly characteristic, with a monoclonal proliferation of plasma cells of variable maturity.[9] Moreover, the positive Congo red stain of the amyloid-like deposits was a definite supporting feature. Amyloid is deposited as a result of fragment of a light chain that is produced by a clonal population of plasma cells in the bone marrow. Amyloid Light chain amyloidosis occurs in association with MM.[1011] Our case also showed negative CD1a stain, which is a specific marker for normal Langerhans cells and pathologic cells in Langerhans Cell Disease.[12]

Learning points/take home messages

Multiple myeloma is a malignancy of plasma cell origin in which there is a monoclonal proliferation of plasma cells. Unifocal form of this entity is plasmacytoma

Oral manifestation in patients with MM is not very rare, but multiple myeloma is often overlooked. Hence, we should include this disease also as a differential diagnosis when considering a patient whose chief complaint is a jaw swelling

Oral lesions are the key to the diagnosis of a more serious systemic disease. A strategic diagnostic protocol enables the dentist for an early diagnosis.