DOI: 10.1148/radiol.2431040397
(Radiology 2007;243:293-296.)
© RSNA, 2007
Case 111: Soft-Tissue Lymphoma1
Bert P. M. ter Braak, MD,
Gerard L. Guit, MD and
Johan L. Bloem, MD
1 From the Leiden University Medical Center, Radiology C2-S, PO Box 9600, 2300 RC Leiden, the Netherlands (B.P.M.t.B., J.L.B.); and Kennemer Gasthuis, Location EG, Radiology, Haarlem, the Netherlands (G.L.G.). Received February 29, 2004; revision requested May 6; revision received August 9; accepted September 2; final version accepted October 15.
Correspondence: Address correspondence to B.P.M.t.B, Department of Radiology, Albert Schweitzer Hospital, Dordwijk, Albert Schweitzerplaats 25, 3318 AT Dordrecht, the Netherlands (e-mail: bpmterbraak{at}yahoo.com).
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HISTORY
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An 86-year-old man presented with painful swelling of the posterior aspect of his right ankle. Insidious swelling had been present for more than 10 years without causing pain; however, in the 10 days prior to presentation, the swelling had caused severe pain. Further history taking revealed no clues as to the cause of this swelling. At the time of presentation, radiographs and magnetic resonance (MR) images were obtained. Within 1 week of radiography and MR imaging, ultrasonography (US) and US-guided biopsies were performed.
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IMAGING FINDINGS
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Conventional radiography revealed soft-tissue swelling on the posterior side of the right ankle, without osseous abnormalities (Fig 1). MR imaging revealed a mass that enveloped the Achilles tendon (Fig 2). The mass was isointense relative to muscle on T1-weighted images (Fig 2a) and hyperintense to muscle on T2-weighted images (Fig 2c). It enhanced uniformly after intravenous administration of gadoterate meglumine (Fig 2b). The mass did not contain any fat. The Achilles tendon itself appeared normal. The signal intensity of the cortex and bone marrow of the distal tibia and talus was normal. There was no joint effusion. US depicted an ill-defined mass that surrounded the normal-appearing Achilles tendon (Fig 3).
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Figure 1: Conventional lateral radiograph of the right ankle. Soft-tissue swelling (*) at the posterior ankle obscures the Achilles tendon and occupies the fat body deep to the Achilles tendon (Kager fat body). The mass does not cause osseous abnormalities. C = calcaneus, T = talus, Ti = tibia.
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Figure 2a: Sagittal T1-weighted (a) spin-echo (repetition time msec/echo time msec, 400/20) and (b) fast field-echo (575/20) frequency-selective fat-saturation gadoterate meglumine–enhanced (Dotarem; Guerbet, Paris, France) MR images of the right ankle. (c) Transverse T2-weighted fast spin-echo (4031/95; turbo factor, 13) MR image of the right ankle. F = fibula. Around the Achilles tendon (arrowheads) sits a lesion (*) that is homogeneous and isointense relative to muscle on a, hyperintense relative to muscle on c, and moderately enhances after intravenous administration of gadoterate meglumine (b). The lesion does not contain fat. The lesion envelops the Achilles tendon, but the tendon itself appears normal. No cortical or intramedullary abnormalities are seen, and there is no joint effusion. C = calcaneus, T = talus, Ti = tibia.
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Figure 2b: Sagittal T1-weighted (a) spin-echo (repetition time msec/echo time msec, 400/20) and (b) fast field-echo (575/20) frequency-selective fat-saturation gadoterate meglumine–enhanced (Dotarem; Guerbet, Paris, France) MR images of the right ankle. (c) Transverse T2-weighted fast spin-echo (4031/95; turbo factor, 13) MR image of the right ankle. F = fibula. Around the Achilles tendon (arrowheads) sits a lesion (*) that is homogeneous and isointense relative to muscle on a, hyperintense relative to muscle on c, and moderately enhances after intravenous administration of gadoterate meglumine (b). The lesion does not contain fat. The lesion envelops the Achilles tendon, but the tendon itself appears normal. No cortical or intramedullary abnormalities are seen, and there is no joint effusion. C = calcaneus, T = talus, Ti = tibia.
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Figure 2c: Sagittal T1-weighted (a) spin-echo (repetition time msec/echo time msec, 400/20) and (b) fast field-echo (575/20) frequency-selective fat-saturation gadoterate meglumine–enhanced (Dotarem; Guerbet, Paris, France) MR images of the right ankle. (c) Transverse T2-weighted fast spin-echo (4031/95; turbo factor, 13) MR image of the right ankle. F = fibula. Around the Achilles tendon (arrowheads) sits a lesion (*) that is homogeneous and isointense relative to muscle on a, hyperintense relative to muscle on c, and moderately enhances after intravenous administration of gadoterate meglumine (b). The lesion does not contain fat. The lesion envelops the Achilles tendon, but the tendon itself appears normal. No cortical or intramedullary abnormalities are seen, and there is no joint effusion. C = calcaneus, T = talus, Ti = tibia.
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Figure 3a: (a) Sagittal and (b) transverse US images of the right ankle show an ill-defined mass (*) around the normal-appearing Achilles tendon (arrowheads). The talus (white arrow) and distal tibia (black arrow) are also seen.
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Figure 3b: (a) Sagittal and (b) transverse US images of the right ankle show an ill-defined mass (*) around the normal-appearing Achilles tendon (arrowheads). The talus (white arrow) and distal tibia (black arrow) are also seen.
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DISCUSSION
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Diffuse large B-cell lymphoma was diagnosed in this patient. Lymphoid neoplasms are divided into three categories: Hodgkin lymphomas, non-Hodgkin lymphomas, and plasma cell neoplasms. The most recent classification system for non-Hodgkin lymphomas, lymphocytic leukemia, and plasma cell neoplasms is the Revised European-American Classification of Lymphoid Neoplasms, which was updated under the auspices of the World Health Organization in 2001 (1).
A histologic examination is needed to assign the correct diagnosis. Approximately 80%–85% of lymphoid neoplasms originate from B cells. Since lymphoid neoplasms derive from the immune system, they often lead to immune system abnormalities. Lymphoid neoplasms are monoclonal because they stem from one transformed cell (2). Diffuse large B-cell lymphomas make up almost 20% of all cases of non-Hodgkin lymphoma, and they affect slightly more male than female subjects. Clinically, lymphoid neoplasms display a wide spectrum of behavior. Median age of onset is 60 years. Characteristically, patients with diffuse large B-cell lymphoma have a fast-growing mass at either a single nodal or an extranodal location (2). These masses are often symptomatic (2). Sites of primary extranodal non-Hodgkin lymphoma are the gastrointentestinal tract (gastrointentestinal associated lymphoid tissue), respiratory tract (mucosal associated lymphoid tissue or bronchial associated lymphoid tissue), orbit, skin, bone, testis, and central nervous system (3). The prevalence of true extranodal soft-tissue lymphoid neoplasms is low. In a series performed at the Mayo Clinic, only eight (0.1%) of 7000 patients with lymphoid neoplasms had primary extranodal soft-tissue lymphoma in the extremities (4). In a series performed at the Armed Forces Institute of Pathology over a 10-year period, Kransdorf (5) found 472 (1.2%) extranodal soft-tissue lymphomas in 38 484 patients with malignant soft-tissue tumors. In patients with end-stage disease, lymphoid neoplasms may extend into soft tissues, such as muscle.
As stated previously, patients with diffuse large B-cell lymphoma typically have a fast-growing mass at either a single nodal or an extranodal location that is often symptomatic (2). This patient's clinical history of a slowly growing soft-tissue mass of 10 years duration that caused severe pain for 10 days prior to presentation was unusual. History taking and further work-up did not yield an explanation for this unusual set of circumstances.
The appearance of extranodal soft-tissue lymphoma on conventional radiographs can be unremarkable and can consist of soft-tissue swelling without bone abnormalities, as was the case in this patient (6). Extranodal soft-tissue lymphomas with secondary extension into cortical bone and the medullary cavity can appear to be mixed lytic and sclerotic lesions (7). It should be kept in mind that conventional radiographic findings can lead physicians to undervalue the bone extent of soft-tissue lymphomas (7). Secondary osseous involvement can be better evaluated with MR imaging.
At US, extranodal soft-tissue lymphomas appear as ill-defined hypoechoic masses. Intramuscular lymphomas display coarsening of fibroadipose septa and swelling of the muscle bundles (8).
At computed tomography (CT), the attenuation of lymphoid neoplasms resembles that of muscle, with varying degrees of enhancement after intravenous administration of contrast material. If a lymphoid neoplasm resides within a muscle, it may appear as a focal mass or as a diffuse enlargement of the muscle, with or without loss of fat planes (7,9). Calcifications are rare (6). Lymphomas can also create a thick mantle and envelop normal anatomic structures, such as bone and tendons, without invading these structures (7,10).
The key point that enables the diagnosis of primary extranodal soft-tissue lymphoma to be made is the extension of the tumor with preservation of the surrounding structures (7,10). In this patient, the Achilles tendon was enveloped but not invaded by the lymphoma. Also, the tumor sat immediately against the cortex of the posterior site of the distal tibia, talus, and calcaneus, without causing abnormalities within the cortex or medullary cavity. These characteristics are best evaluated with MR imaging.
At MR imaging, extranodal soft-tissue lymphomas are homogeneously isointense or slightly hypointense relative to normal muscle on T1-weighted spin-echo images and hyperintense to muscle on T2-weighted spin-echo images. They uniformly enhance after intravenous administration of gadoterate meglumine (3,6,7,9). Because of the better intrinsic soft-tissue contrast with MR imaging relative to CT, MR imaging will better depict tumor extension along preserved anatomic structures.
The majority of soft-tissue masses in the foot and ankle are benign (11). The major differential diagnoses for these masses are gout, rheumatoid arthritis, atypical giant cell tumor of the tendon sheath (GCTTS), and tendon fibroma.
The appearance of a gouty tophus can mimic that of an infectious or neoplastic disease (12). Tophi are of intermediate signal intensity on T1-weighted images and are heterogeneous, with low- and high-signal-intensity areas on T2-weighted images. Most tophi show homogeneous enhancement. Common associated findings are erosion of bone, synovial pannus, joint effusion, soft-tissue edema, and bone marrow edema. All of these findings were absent in this patient. Furthermore, this patient did not have a history of gout.
Rheumatoid arthritis is associated with subcutaneous nodules in 20% of patients (11). At MR imaging, lesions can manifest as subcutaneous nodules, with homogeneous signal intensity on T1-weighted images and peripheral enhancement after injection of a gadolinium chelate. Subcutaneous nodules can exist prior to articular disease. This patient had no clinical, laboratory, or radiologic signs or symptoms of arthritis or rheumatoid arthritis.
GCTTS is the extraarticular counterpart of pigmented villonodular synovitis (13). Hemosiderin-laden synovial masses appear as susceptibility artifacts on gradient-echo T1-weighted MR images and as low-signal-intensity areas on T1- and T2-weighted MR images. Synovial masses show contrast enhancement. Bone erosions and subchondral cysts are present in 56% of patients with pigmented villonodular synovitis of the ankle. For this patient, age, sex, and signal intensity on MR images were not consistent with a diagnosis of GCTTS. GCTTS is most common in the 3rd–5th decades of life and occurs most frequently in female patients.
Fibroma of the tendon sheath can be suspected if MR imaging reveals a focal nodular mass adjacent to a tendon sheath, with decreased signal intensity on all images and little or no contrast enhancement (14). Differentiating between fibroma of the tendon sheath and GCTTS can be difficult. Fibroma is less common than GCTTS. It occurs more commonly in male subjects and younger individuals, and it is more often seen in the upper extremities.
Inclusion of extranodal soft-tissue lymphoma in the clinical differential diagnosis of a soft-tissue lesion at the time of biopsy is important. It alerts the pathologist to this possible diagnosis and ensures optimal processing of the tissue sample. Typically, tissue processing includes analysis of paraffin-embedded sections (for hematoxylin-eosin staining after formalin fixation) and fresh (for immunohistochemical marker studies or flow cytometry) and frozen (for B- and T-cell gene rearrangement studies) tissue samples (15). In this patient, histologic analysis revealed noncohesive, slightly eosinophilic large cells. The nu-clei were round or oval, with varying chromatin patterns. Immunohistochemistry revealed that the cells were positive for CD20 (a B-cell marker), BCL-2, and Ki-67 but negative for CD10, CD35, BCL-6, S-100, and HMB-45. Thus, the tumor was classified as a diffuse large B-cell lymphoma in accordance with the updated Revised European-American Classification of Lymphoid Neoplasms (1).
Inclusion of extranodal soft-tissue lymphoma in the clinical differential diagnosis also affects surgical decision making because lymphoma is not treated with surgery. In general, complete resection is not indicated because it would require the removal of a marker of disease response to chemotherapy, radiation therapy, or both (15).
Chest and abdominal CT examinations were performed at other locations within 3 weeks after the diagnosis was established to rule out lymphoma. These examinations revealed no adenopathy (images not shown). However, the majority of extranodal soft-tissue lymphomas are found to be typical lymphomas at follow-up.
A half-year after initial presentation, this patient developed swelling in the right maxilla, and CT was performed. CT depicted a soft-tissue mass (diameter, 4.7 cm), with the center of the mass located in the floor of the right maxillary sinus and with bony destruction of the floor and ventral wall of the maxillary sinus (images not shown). This mass turned out to be another extra-nodal localization of lymphoma. At that moment, neck, chest, and abdominal CT examinations were repeated. These examinations revealed mediastinal adenopathy and multiple solid lesions within the lung parenchyma.
In conclusion, primary extranodal soft-tissue lymphoma is a rare disease, and it can have various imaging features. A soft-tissue mass enveloping rather than invading normal anatomic structures on MR images in an elderly patient should raise the possibility of primary extranodal soft-tissue lymphoma. Core biopsies are necessary to make a definitive diagnosis, classify the lesion, and construct a treatment plan.
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FOOTNOTES
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Authors stated no financial relationship to disclose.
| Part one of this case appeared 4 months previously and may contain larger images.
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References
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- Cotran RS, Kumar V, Collins T. White cells, lymph nodes, spleen, and thymus. In: Cotran RS, Kumar V, Collins T, eds. Robins pathologic basis of disease. Philadelphia, Pa: Saunders, 1999; 651–675.
- Eustace S, Winalski CS, McGowen A, Lan H, Dorfman D. Skeletal muscle lymphoma: observations at MR imaging. Skeletal Radiol 1996;25(5):425–430.[CrossRef][Medline]
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- Kransdorf MJ. Malignant soft-tissue tumors in a large referral population: distribution of diagnoses by age, sex, and location. AJR Am J Roentgenol 1995;164(1):129–134.[Abstract/Free Full Text]
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- Llauger J, Palmer J, Monill JM, Franquet T, Bague S, Roson N. MR imaging of benign soft-tissue masses of the foot and ankle. RadioGraphics 1998;18(6):1481–1498.[Abstract]
- Yu JS, Chung C, Recht M, Dailiana T, Jurdi R. MR imaging of tophaceous gout. AJR Am J Roentgenol 1997;168(2):523–527.[Abstract/Free Full Text]
- Waldt S, Rechl H, Rummeny EJ, Woertler K. Imaging of benign and malignant soft tissue masses of the foot. Eur Radiol 2003;13(5):1125–1136.[Medline]
- Fox MG, Kransdorf MJ, Bancroft LW, Peterson JJ, Flemming DJ. MR imaging of fibroma of the tendon sheath. AJR Am J Roentgenol 2003;180(5):1449–1453.[Abstract/Free Full Text]
- Damron TA, Le MH, Rooney MT, Vermont A, Poiesz BJ. Lymphoma presenting as a soft tissue mass: a soft tissue sarcoma simulator. Clin Orthop Relat Res 1999;360:221–230.[Medline]
Congratulations to the individual who submitted the most likely diagnosis (soft-tissue lymphoma) for Diagnosis Please, Case 111. The name and location of the individual, as submitted, is as follow:
- Fernando Idoate, Pamplona, Spain
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HISTORY
IMAGING FINDINGS
