DOI:10.2214/AJR.04.1787
AJR 2006; 186:821-827
© American Roentgen Ray Society
Radiologic Manifestations of Primary Solitary Extramedullary and Multiple Solitary Plasmacytomas
Gaik Cheng Ooi1,
James Chor-Sang Chim2,
Wing-Yeh Au2 and
Pek-Lan Khong1
1 Department of Diagnostic Radiology, The University of Hong Kong and Queen Mary
Hospital, K405, Hong Kong SAR, Hong Kong.
2 Department of Medicine, The University of Hong Kong and Queen Mary Hospital,
Hong Kong SAR, Hong Kong.
Received November 18, 2004;
accepted after revision February 7, 2005.
Address correspondence to G. C. Ooi
(cgcooi{at}hkucc.hku.hk).
Abstract
OBJECTIVE. Primary solitary extramedullary and multiple solitary
plasmacytomas are rare manifestations of plasma cell tumors. This study
reviews their imaging spectrum in 12 patients.
CONCLUSION. Imaging features of primary solitary extramedullary and
multiple solitary plasmacytomas are nonspecific but are compatible with solid
tumors that are isointense on T1-weighted images and iso- to hyperintense on
T2-weighted images relative to muscle and white matter with variable
enhancement. Large tumors may show necrosis and destruction, infiltration, or
encasement of adjacent structures. Multiplicity of lesions and regional
lymphadenopathy were evident on imaging in only five cases each. Imaging alone
cannot differentiate these tumors from more common malignant entities such as
carcinoma, meningioma in cases of intracranial extramedullary plasmacytomas,
or metastasis from other primaries. The role of imaging should be focused on
early detection of additional or recurrent lesions and the presence of
regional lymphadenopathy, which will influence clinical management.
Keywords: CT • MRI • oncologic imaging • plasma cell tumor • plasmacytoma
Introduction
Plasmacytoma, a neoplastic proliferation of plasma cells, is one form of
plasma cell dyscrasia that may manifest as multiple myeloma, primary
amyloidosis, or monoclonal gammopathy of unknown significance. Plasmacytoma
may be primary or secondary to disseminated multiple myeloma and may arise
from osseous (medullary) or nonosseous (extramedullary) sites. Primary
extramedullary plasmacytoma can be solitary or multiple
[1]. The International Myeloma
Working Group in 2003 recognized a separate classification of plasmacytomas
that occur as multiple sites of disease in soft tissue, bone, or both soft
tissue and bone as multiple solitary plasmacytoma
[2]. Primary extramedullary
plasmacytoma is rare, accounting for only 4% of all plasma cell tumors, the
majority (80%) of which occur in the upper aerodigestive tract
[2,
3]. Skin and the
gastrointestinal tract are less common sites.
Primary plasmacytoma, whether osseous or nonosseous, is distinguished from
multiple myeloma by the absence of hypercalcemia, renal insufficiency and
anemia, normal skeletal survey, absence of bone marrow plasmacytosis, and
serum or urinary paraprotein level of less than 2 g/dL
[3-5].
The clinical course and prognosis of solitary bone plasmacytoma,
extramedullary plasmacytoma, multiple solitary plasmacytoma, and multiple
myeloma differ, leading some to consider these as separate disease entities
rather than a spectrum of the same disease
[2-4].
Because of its rarity, radiologic descriptions of primary solitary
extramedullary plasmacytoma and multiple solitary plasmacytoma have been
confined to case reports. The purpose of this review is therefore to study the
imaging features and role of imaging in primary solitary extramedullary
plasmacytoma and multiple solitary plasmacytoma presenting over a 16-year
period to our institution.
Materials and Methods
All imaging and clinical and laboratory data of 21 cases of primary
plasmacytoma treated at our institution, a tertiary referral center for
hematologic malignancies, from 1988 to 2004 were retrieved from the
institutional database. Diagnostic criteria included biopsy showing plasma
cell infiltration; absence of lytic bone lesions on skeletal survey except at
the site of disease; bone marrow plasmacytosis value of less than 5% of all
nucleated cells in a random bone marrow sample; serum or urinary paraprotein
level of less than 2 g/dL; and absence of anemia, hypercalcemia, or renal
impairment, which is suggestive of systemic myeloma
[1,
3]. Primary plasmacytoma was
characterized as solitary bone plasmacytoma when a single bone plasmacytoma
was present [2,
3], solitary extramedullary
plasmacytoma when a solitary soft-tissue plasmacytoma was present
[1-3],
or multiple solitary plasmacytoma when there was more than one localized bone
or extramedullary tumor of clonal plasma cells
[1,
2]. Of the 21 cases of primary
plasmacytoma, seven cases of solitary bone plasmacytoma were excluded. Imaging
was available in 12 (eight men; mean age ± SD, 59.7 ± 13.6
years) of the remaining 14 cases of primary plasmacytomas.
All imaging examinations performed at presentation of illness and
subsequent follow-up were reviewed together by two experienced radiologists.
These comprised conventional radiographs, CT scans, MR images, and
radionuclide bone scans. The site of the plasmacytoma and its enhancement
features and the presence of invasion of adjacent structures, bone destruction
or erosion, and enlarged regional lymph nodes were noted. CT scans were
obtained on one of two scanners (LightSpeed or HiSpeed, GE Healthcare), and
MRI was performed on a 1.5-T scanner (Signa, GE Healthcare). One unenhanced
CT, 15 contrast-enhanced CT, and three gadolinium-enhanced MR scans were
reviewed. Two radionuclide bone scans were also available for review.
Results
There were six patients with solitary extramedullary plasmacytoma (three
men; mean age ± SD, 60.3 ± 18.6 years) and six with multiple
solitary plasmacytoma (five men; mean age ± SD, 59 ± 7.8 years).
A multiplicity of multiple solitary plasmacytoma lesions was noted only after
radiologic evaluation in five of the six cases. Plasmacytomas in four cases of
multiple solitary plasmacytoma comprised multiple extramedullary
plasmacytomas, whereas in two cases a bone plasmacytoma and an extramedullary
plasmacytoma coexisted. Two cases of solitary extramedullary plasmacytoma and
one case of multiple solitary plasmacytomas relapsed within a year of
treatment without evidence of disseminated bone marrow involvement or serum or
urinary paraprotein level of more than 2 g/dL. The solitary extramedullary
plasmacytoma cases relapsed as multiple solitary plasmacytomas in the lymph
nodes, pancreas, and skin in one case and in the adrenal gland and mediastinum
in the second case. The multiple solitary plasmacytoma case relapsed with a
solitary pelvic extramedullary plasmacytoma. In total, 23 plasmacytoma lesions
including the recurrent lesions were reviewed
(Table 1), 21 of which were
extramedullary plasmacytomas in the axillary lymph nodes (n = 1),
head and neck (n = 7), thorax (n = 6), and abdomen
(n = 7). Bone involvement (humerus and rib) in two multiple solitary
plasmacytoma cases was lytic and ill-defined; an enhancing soft-tissue
component was associated with the rib lesion.
All extramedullary plasmacytoma lesions were generally well-defined
soft-tissue masses on CT, isointense to muscle and white matter on T1-weighted
images, and iso- to hyperintense to muscle and white matter on T2-weighted
images, with heterogeneous enhancement especially on MRI. Infiltration of
adjacent fat was noted in three relatively small (1-2 cm) extramedullary
plasmacytomas (renal, nasal, and skin)
(Fig. 1A), whereas bone erosion
was present in three larger (4.5-7 cm) extramedullary plasmacytomas arising in
the mediastinum, nose, and neck and destroying the adjacent sternum, medial
maxillary wall and nasal septum (Fig.
2), and transverse process of thoracic vertebra, respectively.
Vascular encasement was found in three large extramedullary plasmacytoma
lesions, which ranged in size from 7 to 15 cm, arising in the lung (Figs.
3A and
3B), mediastinum, and kidney
(Figs. 4A,
4B,
4C, and
4D). On CT, the lung
extramedullary plasmacytoma was shown to infiltrate the pleura and pericardium
with a second separate lesion arising from the right atrium and superior vena
cava (Fig. 3B), causing this
solitary extramedullary plasmacytoma to be reclassified as a case of multiple
solitary plasmacytoma. Central necrosis was present in a 15 x 10 cm
renal and a 7 x 4 cm adrenal extramedullary plasmacytoma (Figs.
4A,
4B,
4C, and
4D). The smaller of the two
renal extramedullary plasmacytomas showed marked heterogeneous arterial
enhancement akin to renal cell carcinoma.
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Fig. 1A —58-year-old woman with treated primary extramedullary plasmacytoma
of mediastinum who relapsed with multiple solitary plasmacytoma 9 months
later. Axial enhanced CT scans show multiple enhancing cutaneous
(arrowheads, A) and subcutaneous (arrows, A)
lesions and heterogeneously enhancing pancreatic extramedullary plasmacytoma
(arrows, B).
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Fig. 2 —63-year-old man with nasal extramedullary plasmacytoma. Unenhanced
axial CT scan through head shows large soft-tissue mass arises from right
nasal passage and extends anteriorly (black arrow) through nasal ala
resulting in deviation and erosion of nasal septum and erosion of medial wall
of right maxillary sinus (white arrows).
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Fig. 3B —53-year-old woman with multiple solitary plasmacytoma. Coronal
reformatted CT image shows second lesion arising from superior aspects of
right atrium (arrowheads) with extension of intraatrial
extramedullary plasmacytoma (arrows) into superior vena cava.
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Fig. 4A —49-year-old man with multiple solitary plasmacytomas arising from
right kidney and mediastinum. Axial contrast-enhanced CT scans through abdomen
show large right renal mass (arrows, B) with areas of necrosis
encasing aorta, inferior vena cava, and superior mesenteric vessels; in
B, large retroperitoneal and mesenteric lymph nodes are visible. Six
months after radiation therapy and chemotherapy, recurrent solitary
plasmacytomas were found in mediastinum and right adrenal.
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Fig. 4B —49-year-old man with multiple solitary plasmacytomas arising from
right kidney and mediastinum. Axial contrast-enhanced CT scans through abdomen
show large right renal mass (arrows, B) with areas of necrosis
encasing aorta, inferior vena cava, and superior mesenteric vessels; in
B, large retroperitoneal and mesenteric lymph nodes are visible. Six
months after radiation therapy and chemotherapy, recurrent solitary
plasmacytomas were found in mediastinum and right adrenal.
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Fig. 4C —49-year-old man with multiple solitary plasmacytomas arising from
right kidney and mediastinum. Axial fast spin-echo T2-weighted scan of thorax
shows hyperintense bilobed soft-tissue mass (arrows) in mediastinum
encasing descending aorta and closely associated with left atrium.
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Fig. 4D —49-year-old man with multiple solitary plasmacytomas arising from
right kidney and mediastinum. Axial postcontrast CT scan shows another
extramedullary plasmacytoma (asterisks) with central necrosis and
heterogeneous enhancement arising from right adrenal gland.
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Imaging findings led to another case of presumed solitary extramedullary
plasmacytoma, an intraorbital superior extraconal mass that had permeated the
adjacent orbital roof (Figs.
5A,
5B, and
5C), to be reclassified as
multiple solitary plasmacytomas when a second asymptomatic lesion was found
posterior to the clivus and dorsum sella. Both lesions were mildly hyperdense
to brain tissue on CT and were isointense to white matter on both T1- and
T2-weighted imaging, with marked enhancement (Figs.
5A,
5B, and
5C). A dural tail was noted in
the posterior clival lesion. The intraorbital mass was hypermetabolic on
radionuclide bone scans. The only other patient who underwent radionuclide
bone scanning was a patient with a neck extramedullary plasmacytoma, which
showed no uptake on the bone scans.
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Fig. 5A —51-year-old woman with multiple solitary plasmacytomas. Coronal CT
scan through orbits shows slightly hyperdense intraorbital superior extraconal
mass compressing left globe with erosion through roof of orbit
(arrows) into anterior cranial fossa.
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Fig. 5B —51-year-old woman with multiple solitary plasmacytomas. On
T1-weighted sagittal scan of brain, a second lesion (M) is revealed to arise
behind dorsum sella and clivus. It appears isointense to white matter.
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Plasmacytomas in the liver and spleen were multiple nodular lesions that
showed mild peripheral enhancement with central hypodense areas.
Involvement of regional lymph nodes was evident on imaging in only five of
six cases with nodal involvement (five cases of multiple solitary
plasmacytomas and one of solitary extramedullary plasmacytoma)
(Fig. 4B). The plasmacytoma
lesions arose in the kidney, pleura, neck, liver and spleen, and nasopharynx
and nose.
Plasmacytosis of less than 5% of all nucleated cells was noted in the bone
marrow of 10 patients, whereas the remaining two patients had normal bone
marrow biopsy results. No urinary or serum paraprotein was found in six
patients, while in the remaining patients, negligible urinary paraprotein
(< 2 g/dL) was present. At the time of writing this article, three patients
had been lost to follow-up, three had died from refractory or progressive
disease, two had died from unrelated causes, three had progressed to multiple
myeloma (one case of extramedullary plasmacytoma and two cases of multiple
solitary plasmacytomas), and one remained in remission.
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Fig. 1B —58-year-old woman with treated primary extramedullary plasmacytoma
of mediastinum who relapsed with multiple solitary plasmacytoma 9 months
later. Axial enhanced CT scans show multiple enhancing cutaneous
(arrowheads, A) and subcutaneous (arrows, A)
lesions and heterogeneously enhancing pancreatic extramedullary plasmacytoma
(arrows, B).
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Discussion
Primary extramedullary plasmacytomas in this study irrespective of solitary
(extramedullary plasmacytoma) or multiple (multiple solitary plasmacytomas)
lesions manifested as soft-tissue tumors with variable mass effect. Large
lesions showed aggressive traits such as infiltration and destruction of
adjacent bone, muscle, and fat and vascular encasement. Extramedullary
plasmacytoma lesions classically arise in the upper aerodigestive tract, with
a predilection for the head and neck
[1,
4]. In a review of more than
400 published articles, 82.2% of extramedullary plasmacytomas were found in
the upper aerodigestive tract with 17.8% arising in the gastrointestinal
tract, urogenital tract, skin, lung, and breast in that order
[1]. In the present study,
extramedullary plasmacytomas, both solitary and multiple, were found in the
head and neck (30.4%), abdomen (30.4%), and thorax (39.2%), with pure upper
aerodigestive involvement comprising only 13% (n = 3) of the total.
The tumors were soft-tissue masses that appeared isointense on T1-weighted
images and iso- to hyperintense on T2-weighted images relative to muscle and
white matter, with mild to marked heterogeneous enhancement on both CT and
MRI.
Nasal extramedullary plasmacytomas in this series were indistinguishable
from other malignant lesions of the paranasal sinuses, primarily natural
killer cell lymphoma, a tumor peculiar to East Asia
[6]; squamous cell carcinoma;
adenocystic carcinoma; and rhabdomyosarcoma, among others. Bone destruction is
not seen in all cases, although it is common in large paranasal or
nasopharyngeal extramedullary plasmacytomas; CT is superior to MRI in
delineating subtle bone erosions. Intracranial manifestations of
extramedullary plasmacytoma include a solitary extraaxial mass similar to a
meningioma as in our case, diffuse leptomeningeal disease mimicking
leptomeningeal carcinomatosis or lymphoma
[5], and very rarely
intracerebral lesions with vasogenic edema. Other conditions that share
similar imaging features include plasma cell granuloma, lymphoma, metastasis,
dural sarcoma, and infectious meningitis. On a similar note, imaging alone
could not differentiate lung and mediastinal plasmacytomas in this study from
primary bronchogenic carcinomas or lymphomas, although the latter are usually
hypodense without significant enhancement.
Of seven published cases of cardiac plasmacytomas with microscopic
description, four were an extramedullary manifestation of multiple myeloma,
one was a solitary intracardiac extramedullary plasmacytoma, and two were
multiple solitary plasmacytomas
[7]. Both atria, particularly
the right, were involved in nearly all cases including our own. It has been
postulated that in disseminated multiple myeloma, circulating plasma cells
implant in at least the right atrium via the venous system
[7]. Differential diagnoses
include the more common atrial myxoma, other intracardiac metastases, and
sarcomas.
Nearly 10% of primary extramedullary plasmacytomas occur in the
gastrointestinal tract, with the stomach and colon as the most common sites
followed by the small bowel and esophagus
[1]. Although liver, spleen,
and lymph nodes are common extramedullary manifestations of multiple myeloma,
primary extramedullary plasmacytomas of these organs—including the
pancreas and adrenal gland—are extremely rare. The liver and spleen
extramedullary plasmacytomas in this study resembled metastases. The few
published cases of adrenal extramedullary plasmacytoma, including ours, ranged
from 3.5 to 10 mm; were heterogeneously enhancing solid tumors; and did not
show signal reduction on opposed phase MRI, a finding that typifies adenoma.
Renal extramedullary plasmacytoma can manifest as a very large mass with
enlarged retroperitoneal lymph nodes, a perinephric mass akin to metastatic
melanoma, or a vascular mass that mimics renal cell or transitional cell
carcinoma [8].
Regional lymphadenopathy was noted on imaging in half of our patients. This
underscores the importance of local treatment to regional lymph nodes and the
usefulness of imaging in staging primary plasmacytoma
[2,
3], particularly in the head
and neck region where regional lymph node recurrence occurs after radiation
therapy in 7% of the patients
[9]. Treatment of primary
plasmacytoma is aimed at local control with local radiation therapy, surgical
resection, or both depending on the site. Systemic therapy, such as
chemotherapy or autologous stem cell transplantation, is recommended for
refractory, recurrent, and multiple plasmacytomas
[1,
2,
4]. The increasing use of MRI,
CT, and PET in the staging and evaluation of apparently solitary plasmacytomas
may reveal multiple soft-tissue lesions or additional bone lesions
[10,
11]. MRI of the spine has been
reported to be a useful prognostic tool in monoclonal gammopathy of unknown
significance, asymptomatic multiple myeloma, and established multiple myeloma,
revealing additional bone lesions in 40% of patients with stage I multiple
myeloma and 50% with asymptomatic multiple myeloma
[12]. Whole-body MRI may be
another technique to consider in the staging of apparent solitary
extramedullary plasmacytoma because the detection of multiple, recurrent, or
new lesions will influence the course of management—that is, when
systemic chemotherapy or autologous stem cell transplantation may be
instituted.
Despite the retrospective nature of this study and the small number of
cases involved, we conclude that the imaging features of primary solitary
extramedullary plasmacytoma and multiple solitary plasmacytomas are
nonspecific but are compatible with solid tumors with invariable enhancement.
Large tumors may show areas of necrosis and are usually associated with
destruction, infiltration, or encasement of adjacent structures. Imaging alone
cannot differentiate these tumors from more common malignant entities such as
carcinoma, meningioma in cases of intracranial extramedullary plasmacytoma, or
metastasis from other primaries. The role of imaging should be focused on the
early detection of additional or recurrent lesions and the presence of
regional lymphadenopathy, which will influence clinical management.
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Abstract
Introduction
