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Journal of Clinical Oncology, Vol 23, No 13 (May 1), 2005: pp. 3143-3145 © 2005 American Society of Clinical Oncology. DOI: 10.1200/JCO.2005.06.011
Plasma Cell ProblemsCASE 3. Plasmacytoma Mimicking a Paraganglioma of the Skull Base: Diagnostic Value of Somatostatin Receptor ScintigraphyHôpital Lariboisière (Assistance Publique -Hôpitaux de Paris), Paris, France A 63-year-old man was referred for evaluation of severe pain in the left temporal-occipital region, of 1 week's duration. He reported a 1-year history of mild pulsatile tinnitus with slight hearing loss in the left ear and brief episodes of unsteadiness. He mentioned that left cervical spine rotation was painful and limited for 1 year. Otoscopic examination revealed a reddish mass located in the anteroinferior part of the eardrum. The rest of the ear-nose-throat examination was normal. Computed tomography scan showed a mass enlarging the jugular foramen, eroding the plate of bone of the lateral aspect of the jugular fossa and extending laterally into the middle ear, reaching the vertical portion of the carotid artery anteriorly, and protruding in the cerebellopontine angle medially. Magnetic resonance imaging (MRI) revealed a homogeneous lesion giving an isosignal on T1- and T2-weighted images (Fig 1, arrow). No enhancement was observed after administration of gadolinium. Diagnosis of paraganglioma was highly evoked, but a meningioma or a schwannoma could not be strictly excluded. Therefore, 111In-pentetreotide somatostatin receptor scintigraphy (SRS) was performed to rule out a schwannoma, which does not express somatostatin receptors, and then to avoid arteriography with respect to the flow diagram we proposed previously.1 SRS, performed 4 hours and 24 hours after intravenous injection of 162 MBq 111In-[DTPA-D-Phe1] octreotide, displayed a very high tracer uptake in the skull base tumor (Fig 2A). Moreover, it displayed multiple costal and vertebrae hot spots (Fig 2B) and a diffused bone marrow uptake. technetium-99m (99mTc) HMDP-bone scintigraphy was normal. Secondarily performed angio-MRI did not disclose any hypervascularization of the cervical mass, which measured 45 mm in long axis and 38 mm in transversal axis. Skeletal radiologic survey was normal except for osteolysis involving the left base of the skull. Vertebral MRI study was carried out to explore lumbar hot spots and displayed multiple nodular and focal lesions with low T1 signal and high T2 signal, along with normal signal after gadolinium injection (Fig 3A and B). There was a marked coincidence of the positive lesions in SRS (Fig 3C) and MRI survey at the thoracolumbar spine, but largest nodular lesions, in MRI. Computed tomography scan of the craniocervical region showed osteolysis of the left lateral mass of C1 vertebra. The differential diagnosis included bone metastases secondary to a paraganglioma, histiocytosis, plasmacytomas, and so on. Biologic investigations showed a monoclonal peak in the gammaglobulins. Immunofixation and immunoelectrophoresis detected an immunoglobulin (Ig) G kappa monoclonal component without any decrease in serum IgA and IgM levels. Proteinuria was negative, but immunoelectrophoresis displayed free kappa chain urine excretion. Hemogram, erythrocyte sedimentation rate, serum C-reactive protein, beta 2 microglobulin, albumin, and calcium levels were within normal limits.
A biopsy of the skull mass was performed by an external ear approach, and pathologic examination displayed a large number of mature plasmacytes (Fig 4). Cells were positive for monoclonal kappa light chain staining. Sternal and iliac crest aspiration smears were normal. By contrast, pathologic examination of the iliac crest biopsy disclosed a nodular focus of atypical plasmacytes, further suggesting that these multiple plasmacytomas were currently switching toward multiple myeloma. The patient received initially 30 mg/d of prednisone and 90 mg pamidronate infusion. Radiotherapy of the skull mass including the first cervical vertebrae and the external ear canal, was delivered at 44 Gy in 4 weeks. This was preceded by three consecutive steroid pulses since the patient started to develop changes in his voice, and paresis of the left soft palate, suggesting a jugular foramen syndrome. After 5 weeks, he was improved. He received monthly polychemotharapy for 12 months and achieved partial remission with a 6-month plateau.
In this case, presenting as an unique skull location, SRS led to the incidental detection of several skeletal hot spots of the spine and ribs, allowing for the diagnostic suspicion of multiple plasmacytomas or multiple myeloma. Facing an apparent solitary plasmacytoma, investigations must rule out multiple myeloma since a surgical procedure and/or radiotherapy should be considered in the treatment of solitary plasmacytoma, and chemotherapy postponed.2 One third of patients with an apparently solitary plasmacytoma of bone have evidence of other plasma cell tumors on MRIs of the spine, and this finding is associated with persistence of the monoclonal component after irradiation therapy, which may be of poor prognostic significance.3 Skeletal survey can lead to false-negative results or underestimate the extent of the disease, when silent lesions, such as posterior vertebral arch, are already present.4 In stage I multiple myeloma, MRI has allowed for better staging of the disease by demonstrating unexpected and early lesions at the spine or the pelvic level.5,6 However, MRI is limited by the field of the coil and cannot be compared with a whole-body scan. Scintigraphy using 99mTc-diphosphonates is not appropriate for the detection of osteolytic lesions as observed in our case. 99mTc-MIBI, a lipophilic agent which accumulates preferentially in living malignant cells, yielded promising results in identifying sites of active myeloma either in untreated7,8 and in previously treated patients.9,10 The prognostic value of 99mTc-MIBI scintigraphy has been emphasized.11 More recently, [18F]FDG positron emission tomography seems to reveal high accuracy in detecting multiple myeloma12 but it is still under investigation.13 Persistent positive [18F]FDG positron emission tomography findings after induction therapy could predict early relapse. As myeloma cells, just as other hematological normal cells,14,15 express somatostatin receptors predominantly sst2, sst3 and sst5,16 somatostatin receptor scintigraphy could be a potential relevant tool in the staging of some myelomas or plasmacytomas. Interestingly, in the present case, there was a striking coincidence of the detected lesions in both SRS and MRI survey, especially at the thoracolumbar spine while the skeletal x-ray survey only displayed osteolytic lesion of the skull. Surprisingly, in vivo studies using SRS in myeloma or plasmacytomas are lacking in the literature. To our knowledge, only a single case of intracranial plasmacytoma has been reported17 but did not display any tracer uptake. Choice of the best radiotracer, ie, 99m-Tc-MIBI, [18F]FDG, or 111In-pentetreotide, remains to be determined and compared to spinal MRI survey, for cases of myeloma, plasmacytomas and monoclonal gammopathy of undetermined significance. Authors' Disclosures of Potential Conflicts of Interest The authors indicated no potential conflicts of interest.
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Copyright © 2005 by the American Society of Clinical Oncology, Online ISSN: 1527-7755. Print ISSN: 0732-183X
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