Case Report. Solitary Plasmacytoma of Bone 病例報告 骨孤立性漿細胞瘤 INTRODUCTION CASE REPORT

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1 台灣癌症醫誌 (J. Cancer Res. Pract.) 26(2),77-81, 2010 Case Report journal homepage: Solitary Plasmacytoma of Bone Chih-Hung Lin 1, Kun-Chuan Chang 1 *, Ching-Jung Wu 2, 3 1 The Second Surgical Intensive Care Unit, Department of Surgery, Cathay General Hospital, Taipei, Taiwan 2 Department of Radiation Oncology, Cathay General Hospital, Taipei, Taiwan 3 Department of Radiation Oncology, Tri-service General Hospital, Taipei, Taiwan Abstract. Solitary plasmacytoma of bone (SPB) is a rare disease with a unique presentation on magnetic resonance imaging historically named mini brain. Here we report a case of solitary plasmacytoma of bone (SPB) of the fifth lumbar vertebral body with a rapid course of deterioration caused by compression fracture and provide a literature review to remind physicians about early diagnosis and treatment of this disease. 病例報告 Keywords : plasmacytoma, magnetic resonance imaging, mini brain 骨孤立性漿細胞瘤 林志鴻 1 張坤權 1 * 吳錦榕 2, 3 1 國泰綜合醫院外科部神經外科第二加護病房 2 國泰綜合醫院放射腫瘤科 3 三軍總醫院放射腫瘤部 中文摘要骨孤立性漿細胞瘤 Solitary plasmacytoma of bone (SPB) 是罕見的腫瘤, 其核磁共振影像具有特異之表現, 稱為 " 迷你腦 " 本病例報告為一迅速惡化之第五腰椎椎體骨孤立性漿 細胞瘤合併壓迫性骨折, 希望以此病例報告及文獻回顧提醒臨床醫師及早發現給予適當治療 關鍵字 : 漿細胞瘤 核磁共振影像 迷你腦 INTRODUCTION Solitary plasmacytoma of bone (SPB) represents only 5% of all plasma cell neoplasia [1]. In the United States, there are approximately 450 new cases per year. There are several clinical features of SPB: a male / female ratio of 2/1, predominant axial skeleton, and a median age at diagnosis of 55 years old, which is more than 10 years younger than that of multiple myeloma [1-3]. Although most image findings of SPB lack specificity, causing a diagnostic problem [4], there is a specific sign mentioned in the literature called mini brain, which is considered pathognomonic for this disease. CASE REPORT This 56-year-old man had suffered gradual onset

2 78 C. H. Lin et al./jcrp 26(2010) SR IL Figure 1A. T1W MRI on April 15, 2010 shows hypoinstense lesion on the fifth lumbar vertebral body Figure 1B. Axial view T2W MRI of the fifth lumbar vertebral body on April 2010 shows a lesion with heterogenous hyperintensity of pain on his left buttock since February He emphasized no trauma history. The condition deteriorated, and his pain began to radiate to the left thigh and upper calf with numbness in April As his pain grew worse, he went to a medical center where lumbar spine magnetic resonance imaging (Figure 1A) showed a lesion at the fifth lumbar spine vertebral body with hypertrophy of nearby intervertebral discs. Under the impression of benign disease process, the patient was given only medical treatment and rehabilitation therapy. However, his symptoms progressed, and he visited our neurosurgical clinic on June On physical examination, Straight Leg Raising Test on the right lower extremity was 80 degrees and *Corresponding author: Dr. Kun-Chuan Chang * 通訊作者 : 張坤權醫師 Tel: ext.6022 Fax: tsuyoikadara@cgh.org.tw 60 degrees on the left. Plantarflextion and dorsiflexation of the left foot were weaker than those of the right. Laboratory study showed normal blood cell count, normal erythrocyte sedimentation rate, and normal liver function and renal function tests. On June 15, 2010, magnetic resonance imaging (MRI) of lumbar spine showed remarkable deformity and fracture of the fifth lumbar vertebral body, with a paraspinal mass (Figures 2A,B) obstructing the neuroforamina and causing spinal stenosis. Whole-body bone scan revealed only a solitary corresponding radioactive lesion. On June 19, 2010, laminectomy, tumor biopsy and posterior fusion from the fourth lumbar vertebral body to the first sacral vertebral body were performed to restore the weight-bearing function, and pathology revealed diffuse infiltration of neoplastic plasmacytoid cells with intervening amyloid material (Figures 3,4), therefore a series of sequential laboratory investigations was done: serum total protein=6.4 g/dl; albumin =3.9 g/dl; albumin/globulin ratio=1.6; serum protein

3 C. H. Lin et al./jcrp 26(2010) Figure 1C. Axial view T2W plus proton density MRI at the same site as Figure 1B shows hyperintense mass lesion surrounded by curvilinear hypointese infoldings (arrows), micmicking gyrus of mini brain Figure 2A. T1W MRI of the fifth vertebral body on June 15, 2010 reveals a mass lesion (arrow) with homogenous hypointensity electrophoresis reported: albumin=59.1%, α1-globulin =3.0%, α2-globulin=8.8%, β-globulin=10.8%, γ-globulin=18.3%; urine protein electrophoresis reported: albumin=34.3%, α1-globulin=4.7%, α2-globulin=8.0 %, β-globulin=23.5%, γ-globulin=29.5%; serum IgA = mg/dl, IgM=70.80 mg/dl, IgG= mg/ dl, and serum β2-microglobulin= ug/l. Both serum and urine immunoelectrophoresis revealed no paraprotein at the time of diagnosis. There was no Bence-Jones protein in the urine either. Bone marrow biopsy on the right iliac crest showed normal cellularity without neoplastic cell infiltration. The final diagnosis was solitary plasmacytoma of bone. In consequence, the patient received local radiotherapy of 45 Gy in 25 fractions for 5 weeks on the affected region, and later, he was followed up regularly at clinics of the oncologist. After completion of local radiotherapy, he has no adjuvant or prophylactic chemotherapy because his serum and urine protein immunoelectrophoresis remained negative for myeloma protein. The patient s activity of daily living is Figure 2B. T2W MRI of the same site as Figure 2A shows a heterogenous hyperintense mass lesion surrounded by a curvilinear hypointese infolding (arrow), micmicking gyrus of mini brain

4 80 C. H. Lin et al./jcrp 26(2010) DISCUSSION This patient presented a clinical symptom of lumbar radiculopathy. The presence of a single marrow lesion in the axial skeleton on MRI poses a diagnostic difficulty. The differential diagnosis should include chronic inflammation, plasamcytoma/myeloma and metastasis. In metastasis or multiple myeloma, the nearby intervertebral disc hypertrophy is often absent due to rapid progress behavior of the cancer. However, this finding does not exclude neoplasm. Several documents demonstrate a characteristic image presentafigure 3. H&E stain of lumbar spine surgical biopsy tion that help us diagnose as early as possible: hy- shows diffuse infiltration of neoplastic pointensity of the marrow on T1-weighted (T1W) and plasmacytoid cells with intervening amy- heterogenous hyperintensity on T2-weighted (T2W) loid material (confirmed with crystal violet images with low signal curvilinear void on T2W im- and Congo red stains). Atypical immature ages within the vertebral body (also called the mini plasmacytoid cells possess centrally or ec- brain ) [5-7]. This sign is almost considered a path- centrically located nuclei and indistinct nu- ognomonic finding of SPB, which was also found in cleoli. More mature forms possess eccen- this case (Figures 1B,C and Figures 2A,B). trally located nuclei and perinuclear halo After surgery for structural instability, local irradiation is indicated for every SPB patient, even though complete excision seems to cure this disease. The use of radiotherapy is based upon data from a retrospective study, which included 258 patients. Patients who received localized radiotherapy had a significant lower rate of local relapse than those underwent observation alone (12% versus 60%) [8]. Most oncologist recommend the dose of 40 to 50 Gy in fractions for four weeks [3,8]. The use of prophylactic or adjuvant chemotherapy is still under debate. Although two studies compared between radiotherapy alone and combined radiotherapy and adjuvant chemotherapy [9,10], the relapse rates were not significantly different and the Figure 4. Immunohistochemical study shows: VS38c: sample sizes were too small. Even though previous positive, CD56: positive, Mum-1: positive, case series demonstrated that about 50 to 60 percent of CD45RB (LCA): weakly positive SPB finally develop multiple myeloma [3,11], we still do not recommend prophylactic or adjuvant chemotherapy [12]. now totally independent, and he has resumed previous work without social function loss. Clinicians should carefully follow up SPB. As a general rule, serum and urine protein immunoelectro-

5 C. H. Lin et al./jcrp 26(2010) phoresis and free light chain data are collected at the time of diagnosis. Later, they should be repeated right after completion of local radiotherapy and at least every three to four months in the first year, then annually from the second year on to determine resolution or relapse of the disease. Both persistent monoclonal proteins greater than 0.5 g/dl one year after diagnosis and abnormal free light chain ratio at the time of diagnosis are poor prognostic factors [13]. On the other hand, complete blood cell count, serum creatinine and serum calcium are also helpful tests. If any paraprotein is detected, whole body bone scan, complete spinal MRI, or whole-body positron emission tomographic scan should be arranged to detect the development of multiple myeloma early and start treatment. REFERENCES 1. Dores GM, Landgren O, McGlynn KA, et al. Plasmacytoma of bone, extramedullary plasmacytoma, and multiple myeloma: incidence and survival in the United States, Br J Haematol 144: 86-94, Shih LY, Dunn P, Leung WM, et al. Localised plasmacytomas in Taiwan: comparison between extramedullary plasmacytoma and solitary plasmacytoma of bone. Br J Cancer 71: , Frassica DA, Frassica FJ, Schray MF, et al. Solitary plasmacytoma of bone: Mayo Clinic experience. Int J Radiat Oncol Biol Phys 16: 43-48, Li Jian FG, Xu Ke. The clinical imaging performances of solitary plasmacytoma of spine. Chinese J Med Imaging 17: 3, Major NM, Helms CA, Richardson WJ. The "mini brain": plasmacytoma in a vertebral body on MR imaging. AJR Am J Roentgenol 175: , Shah BK, Saifuddin A, Price GJ. Magnetic resonance imaging of spinal plasmacytoma. Clin Radiol 55: , Afonso PD, Almeida A. Solitary plasmacytoma of the spine: An unusual presentation. AJNR Am J Neuroradiol 31: E5, Ozsahin M, Tsang RW, Poortmans P, et al. Outcomes and patterns of failure in solitary plasmacytoma: a multicenter rare cancer network study of 258 patients. Int J Radiat Oncol Biol Phys 64: , Holland J, Trenkner DA, Wasserman TH, et al. Plasmacytoma. treatment results and conversion to myeloma. Cancer 69: , Aviles A, Diaz-Maqueo JC, Garcia EL, et al. Solitary plasmacytoma. A retrospective analysis of 15 cases. Rev Invest Clin 42: , McLain RF, Weinstein JN. Solitary plasmacytomas of the spine: a review of 84 cases. J Spinal Disord 2: 69-74, Dimopoulos MA, Goldstein J, Fuller L, et al. Curability of solitary bone plasmacytoma. J Clin Oncol 10: , Dingli D, Kyle RA, Rajkumar SV, et al. Immunoglobulin free light chains and solitary plasmacytoma of bone. Blood 108: , 2006.