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Year : 2014  |  Volume : 10  |  Issue : 3  |  Page : 726-729

Primary peripheral neurolymphomatosis mimicking synovial sarcoma: FDG PETCT to the rescue

Department of Nuclear Medicine and PETCT, Amrita Institute of Medical Sciences, Cochin, Kerala, India

Date of Web Publication14-Oct-2014

Correspondence Address:
Dr. S Padma
Department of Nuclear Medicine and PETCT, Amrita Institute of Medical Sciences, Cochin - 680 2041, Kerala
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0973-1482.136038

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 > Abstract 

Our understanding of the association between synovial sarcoma and peripheral neurolymphomatosis is limited to a few case reports in literature. Delay in diagnosis or misdiagnosis is possible due to its insidious onset and varied presentation compounded by non-specific imaging findings. Needle biopsy also may not be confirmatory especially, in cases of biphasic sarcoma as in our case, and it may be necessary to proceed to open biopsy. Here, is a case of a non-tender right calf muscle mass, which was reported as biphasic synovial sarcoma by FNAC. Positron emission tomography computed tomography - computed tomography (PETCT) showed right sciatic nerve involvement and multiple infra diaphragmatic lymph nodal lesions. Intensity of 18 F FDG ( 18 Flourine labeled fluro de oxy glucose) uptake and the infra diaphragmatic lymph nodal lesions distribution, was more in favour of a lymphoma diagnosis rather than a sarcoma, (which are usually low metabolically active tumors). Thus, this case highlights the usefulness of FDG PETCT in arriving at a diagnosis in the background of indeterminate clinicopathological and radiologic findings.

Keywords: Biphasic synovial sarcoma, FDG PETCT scan, non-Hodgkins lymphoma, peripheral nerve involvement, sciatic nerve

How to cite this article:
Padma S, Sundaram P S, Praveen Kumar S. Primary peripheral neurolymphomatosis mimicking synovial sarcoma: FDG PETCT to the rescue. J Can Res Ther 2014;10:726-9

How to cite this URL:
Padma S, Sundaram P S, Praveen Kumar S. Primary peripheral neurolymphomatosis mimicking synovial sarcoma: FDG PETCT to the rescue. J Can Res Ther [serial online] 2014 [cited 2021 Nov 28];10:726-9. Available from: https://www.cancerjournal.net/text.asp?2014/10/3/726/136038

 > Introduction Top

Considerable clinicopathological and radiological heterogeneity exists in differentiating biphasic synovial sarcoma from peripheral neurolymphomatosis (PNL) posing a diagnostic challenge. [1] Both synovial sarcoma and PNL are distinct morphological, clinical and genetically defined tumor entities, but with overlapping presentation and findings. [2],[3]

As these investigations are far and few, and time consuming; one needs to resort to other widely available easier diagnostic tests like Positron Emission Tomography - Computed Tomography (PETCT). PETCT serves as a surrogate marker before proceeding to molecular markers especially, in small sample biopsies. It also serves as a guide to biopsy and determines the tumor aggressiveness.

 > Case Report Top

60-year-old male presented with a non-tender right calf muscle swelling and a diagnosis of biphasic synovial sarcoma (FNAC wise) was entertained. Patient was referred to our department for a staging 18 Flourine labeled fluro de oxy glucose ( 18 F FDG) PETCT procedure. Patient had a past history of right total knee replacement. There was no history of any previous lymphoma.

Clinical and neurological examinations were non-contributory. Loco motor system examination showed lower extremities muscle bulk to be asymmetric with a mass lesion involving right calf muscles, and with no fasciculations. Overall tone was normal. Strength was measured on medical research council scale as 4/5 in the right ankle dorsiflexors, 4/5 in the right hamstrings muscles. Sensory examination revealed minimal sensory loss to pinprick along the lateral aspect of the right foot. Electro neuro myography showed a sensomotoric axonal lesion. Magnetic resonance imaging (MRI) showed low to intermediate signal on MR T1 imaging and high signal on T2 imaging in right calf muscle mass raising a possibility of sarcoma.

Eight mCi (millicuries) of 18 F FDG was injected intravenously in euglycemic patient status. Head to ankle PETCT images were acquired using an 8 slice PETCT camera. Contrast enhanced CT was also performed. Images showed a large lobulated heterogeneous mass with intense FDG uptake involving right gastrosoleus muscle (standard uptake value [SUV] max 26.4 g/ml) [Figure 1] and [Figure 2]. Another linear abnormal FDG uptake was seen extending from right mid-thigh to lower end of right tibia level corresponding to thickened right sciatic nerve on CT. Patient also had conglomerate lymph nodal mass with a few discrete nodes involving left common iliac, internal and external iliac (SUVmax 27.6), multiple right external iliac (SUV max 4.6), right inguinal, and popliteal lymph nodes (SUV max 8.7) [Figure 3]. An unsuspected FDG avid left iliac bone lesion was also identified. Biopsy of the lesion revealed diffuse large B-cell lymphoma [Figure 4].
Figure 1a and b: FDG PETCT fused and 3 dimensional coronal images showing intensely FDG avid extranodal lymphomatous involvement of right sciatic nerve (thick arrow) and a large lobulated heterogenous FDG avid mass (thin arrow) involving right gastosoleus muscle (SUV max 26.4 gm/ml)

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Figure 2: (a) FDG PET only coronal images showing the right calf muscle lesion with right sciatic nerve involvement; (b, c) Transaxial contrast enhanced computed tomography (CECT) and fused PET CT images showing the right calf muscle lesion; (d, e) Transaxial CT and fused PET CT images showing the thickened right sciatic nerve

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Figure 3: FDG PETCT transaxial sections showing FDG avid infradiaphragmatic lymph nodal involvement (cursor points to discrete and conglomerate left internal iliac nodes (SUV max 27.6. Another FDG avid left iliac bone lesion was also identified

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Figure 4: Fasicular biopsy-serial paraffin sections of right sciatic nerve (a) H and E staining; (b) Immunostained section with anti-CD20; (c) Immunostained section with anti-CD3.Sections show diffuse endoneural and sub perineural cellular infiltrate with CD 20 positive lymphocytes; (b) Shows large immature lymphocytes with a monoclonal nature indicating diffuse large B cell lymphoma. Scale bars 30 mm

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 > Discussion Top

As demonstrated in this case, the diagnosis of PNL can be challenging and often delayed. The leading clinical sign is usually a progressive and painful neuropathy of the involved neural structures with motor and sensory deficits. [3] Approximately half of the cases have widespread systemic lymphoma at the time of autopsy, and 5% have central nervous system involvement. [3],[4] Neural involvement includes peripheral nerves (60%), spinal nerve roots (48%), cranial nerves (46%) and plexus (40%) with multiple sites involvement in 58%. [4] PNL is related to non-Hodgkin's lymphoma (NHL) in 90%, acute leukemia in 10% cases and remaining may be due to infection, inflammation and drug induced. [4],[5],[6],[7],[8]

As a rule sarcomas are considered to be metabolically low active tumors with preferential lung metastases. Our patient showed an intense FDG accumulation in right calf muscle mass indicating an aggressive type of lymphoma with no lung involvement.

Synovial sarcomas occur in extremities of young adult males in 80-90% cases, most commonly around the knee joint akin to PNL. [1] Histologically and radiologically, differentiating the two may be difficult. [2],[3] Younger age onset, low to intermediate signal on MR T1 imaging and high signal on T2 imaging, morphological characters such as septations, and inhomogeneous mass without clear margins are some of the characters favoring synovial sarcoma. 40% of synovial sarcomas may show high signal on both T1 and T2 images due to intra tumor hemorrhage. [9] Nerve biopsy is considered to be the "gold standard" investigation for PNL.

18 F FDG PETCT plays a pivotal role in staging and therapy response assessment. It helps in differentiating the aggressiveness of lymphomas apart from predicting the disease survival free period. [10] Presumably FDG uptake pattern is based on the fact that indolent and aggressive tumors represent different clones of cells with different glucose metabolism and biologic behaviors. Schöder et al. [11] tried to evaluate whether the intensity of tumor FDG uptake could differentiate indolent and aggressive disease. 97 NHL patients who were either untreated or relapsed/had persistent disease with no treatment in the last 6 months underwent FDG PET. Highest SUV per study was recorded and correlations were made with histopathology. FDG uptake was found to be lower in indolent than in aggressive lymphoma (SUV, 7.0 ± 3.1 vs. 19.6 ± 9.3; P <.01). Despite overlap between indolent and aggressive disease in the low SUV range (indolent, 2.3-13.0; aggressive, 3.2-43.0), all cases of indolent lymphoma had an SUV ≤ 13.

Although, this case report demonstrates the importance of PETCT, there is no data to conclude that PETCT will always be superior to MR in evaluating PNL. Thus, the more adequate recommendation is to obtain both PETCT and MR as they are complimentary. Grisariu et al. [12] retrospectively analyzed 50 patients of PNL. MRI and PETCT were positive in 77 and 84% respectively. Treatment of PNL is controversial and options include systemic chemotherapy, intra-CSF chemotherapy and radiotherapy. Prognosis is usually poor given the challenges (and thus delays) in establishing the diagnosis.

 > Conclusion Top

Both synovial sarcoma and PNL are distinct morphological, clinical, and genetically defined tumor entities, though they bear close resemblance to each other. Diagnosis of PNL may be delayed due to asymptomatic or indolent nature of the disease. While MRI is extremely useful in initial diagnosis of PNL, PETCT provides a whole body screening, anatomical extent of lesions and their metabolic status. It also determines the aggressiveness of the lymphoma thus helps in predicting the course of the disease. Molecular markers are helpful in confirming the diagnosis. Both PETCT and MR serve complimentary to each other in initial diagnosis and management of lymphomas.

 > References Top

Siegel HJ, Sessions W, Casillas MA Jr, Said-Al-Naief N, Lander PH, Lopez-Ben R. Synovial sarcoma: Clinicopathologic features, treatment, and prognosis. Orthopedics 2007;30:1020-5.  Back to cited text no. 1
Folpe AL, Schmidt RA, Chapman D, Gown AM. Poorly differentiated synovial sarcoma: Immunohistochemical distinction from primitive neuroectodermal tumors and high-grade malignant peripheral nerve sheath tumors. Am J Surg Pathol 1998;22:673-82.  Back to cited text no. 2
Quiñones-Hinojosa A, Friedlander RM, Boyer PJ, Batchelor TT, Chiocca EA. Solitary sciatic nerve lymphoma as an initial manifestation of diffuse neurolymphomatosis. Case report and review of the literature. J Neurosurg 2000;92:165-9.  Back to cited text no. 3
Kim DH, Murovic JA, Tiel R, Kline DG. Management and outcomes in 353 surgically treated sciatic nerve lesions. J Neurosurg 2004;101:8-17.  Back to cited text no. 4
Dailey AT, Rondina MT, Townsend JJ, Shrieve DC, Baringer JR, Moore KR. Sciatic nerve sarcoidosis: Utility of magnetic resonance peripheral nerve imaging and treatment with radiation therapy. J Neurosurg 2004;100:956-9.  Back to cited text no. 5
Plotkin SA. Clinical and pathogenetic aspects of varicella-zoster. Postgrad Med J 1985;61 Suppl 4:7-14.  Back to cited text no. 6
Postma TJ, Benard BA, Huijgens PC, Ossenkoppele GJ, Heimans JJ. Long-term effects of vincristine on the peripheral nervous system. J Neurooncol 1993;15:23-7.  Back to cited text no. 7
Re D, Schwenk A, Hegener P, Bamborschke S, Diehl V, Tesch H. Guillain-Barré syndrome in a patient with non-Hodgkin's lymphoma. Ann Oncol 2000;11:217-20.  Back to cited text no. 8
Swarnkar A, Fukui MB, Fink DJ, Rao GR. MR imaging of brachial plexopathy in neurolymphomatosis. AJR Am J Roentgenol 1997;169:1189-90.  Back to cited text no. 9
Okada J, Oonishi H, Yoshikawa K, Itami J, Uno K, Imaseki K, et al. FDG-PET for predicting the prognosis of malignant lymphoma. Ann Nucl Med 1994;8:187-91.  Back to cited text no. 10
Schöder H, Noy A, Gönen M, Weng L, Green D, Erdi YE, et al. Intensity of 18fluorodeoxyglucose uptake in positron emission tomography distinguishes between indolent and aggressive non-Hodgkin's lymphoma. J Clin Oncol 2005;23:4643-51.  Back to cited text no. 11
Grisariu S, Avni B, Batchelor TT, van den Bent MJ, Bokstein F, Schiff D, et al. Neurolymphomatosis: An International Primary CNS Lymphoma Collaborative Group report. Blood 2010;115:5005-11.  Back to cited text no. 12


  [Figure 1], [Figure 2], [Figure 3], [Figure 4]


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