Introduction

Plasmacytoma is malignant proliferation of plasma cell, mainly arise from proliferation of a single clone of B lymphocyte 3% of which present as solitary lesion [1]. The international myeloma working group lists three types of plasmacytoma: solitary plasmacytoma of bones, extramedullary plasmacytoma & multiple plasmacytoma. Solitary plasmacytoma occurs as lytic lesion. An osteolytic plasmacytoma lesion in skull with no systemic involvement is extremely rare [2]. Multiple myeloma, extramedullary plasmacytoma and solitary bone plasmacytoma all are the three subgroup of plasma cell tumor [3].We present a case of plasmacytoma present in frontoparietal region.

Case report : A 77 years male admitted to our department with complaints of gradual enlargement of a painless swelling on his vertex for one year. On examination we found a painless mass in left frontoparietal region measuring about 8.5 × 6.4 cm in diameter which was firm in consistency, not mobile, fixed with underlying & overlying structure, on general physical examination no other abnormality detected, neurological examination was also normal. He has no significant past medical or surgical illness. On MRI of brain revealed a iso to hypointense extra axial lesion involving the left frontoparietal region measuring about 8 × 6 cm causing mass effect over the brain parenchyma.

Figure 1: MRI of brain in t1wi showing iso intense lesion

Figure 2: Scalp swelling about 8.6 × 6.5 cm

Figures 3 and 4: After intravenous gadolinium strong enhancement of lesion make it confused with meningioma.

After Intravenous gadolinium showed strong enhancement of the lesion. On CT scan of brain revealed there is a lytic lesion in left frontoparietal region causing a bone defect (Figures 5 and 6).

Figures 5 and 6: CT scan of skull in bone window shows erosion of frontoparietal part of skull.

On magnetic resonance venogram displayed the superior sagittal sinus is compressed by the tumor. Complete blood count all are within normal range.as our initial diagnosis was may be a case of meningioma or metastasis so we did all metastatic work up. Example: Thyroid scan, Ultrasonography of whole abdomen and tumor marker but all were normal, He underwent craniectomy peroperative tumor was found to involve the subcutaneous tissue to bone up to dura & which was completely extradural, tumor was moderately vascular, total removal of tumor with involved bone was removed (Figures 7 and 8).

Figures 7 and 8: Peroperative tumor removal, after careful dissection of skin tumor found attached with underlying bone & after craniectomy.Cranioplasty was done with bone cement (Figures 9 and 10).

Figures 9 and 10: At 4th post-operative day, en bloc removal of tumor without any residual tumor with cranioplasty.

Histopathology revealed plasmacytoma .his post-operative period was uneventful, as there was no other site of lytic lesion and we removed tumor in en bloc with part of dura so radiotherapy was not performed.

Discussion

Plasma cell tumor are divided in three type solitary plasmacytoma of bone (SPB), extramedullary plasmacytoma & multiple myeloma. Multiple myeloma is systemic disease which involved multiple osteolytic lesions, atypical plasma cell in biopsy , amyloid deposit & abnormalities in immunoglobulin production, and the others are local form of plasma cell tumor , According to Bataille and Sany, the diagnostic criteria for SPB include an isolated tumor composed of malignant plasma cells; absence of other lesions on skeletal radiographic survey; absence of plasmacytosis in the bone marrow, absence of anemia, hypercalcemia, or renal involvement & the Vertebrae and pelvic bones are mostly involved by SPB [3].Solitary plasmacytoma of skull is rare disease and considered to be curable with resection & radiotherapy [4].Due to its rarity most of the time preoperatively it is misdiagnosed as meningioma or metastasis . As compared to SPB the prognosis of solitary plasmacytoma of skull is good if it is diagnosed on strict criteria [1].So making the appropriate diagnosis is necessary for further management & follow up, though from some literature they think that solitary plasmacytoma is the initial presentation of multiple myeloma with progression of time this may convert into multiple myeloma [5].

We went through published literature (Table 1) of patients diagnosed as a case of solitary plasmacytoma of skull received en bloc removal of tumor including cranioplasty [4, 6-12].