AJR 2004; 183:929-932
© American Roentgen Ray Society
Spectrum of Imaging Findings in Abdominal Extraosseous Myeloma
Michael Patlas1,2,
Korosh Khalili1,3,
Marcus J. Dill-Macky1 and
Stephanie R. Wilson1
1 Department of Medical Imaging, University Health Network and Mount Sinai
Hospital, 200 Elizabeth St., Toronto, ON M5G 2C4, Canada.
2 Present address: Department of Radiology, Hamilton General Hospital, Hamilton,
ON L8L 2X2, Canada.
3 Department of Medical Imaging, Princess Margaret Hospital, University Health
Network, 3-964, 610 University Ave., Toronto, ON M5G 2M9, Canada.
Received October 21, 2003;
accepted after revision April 16, 2004.
Address correspondence to K. Khalili.
Abstract
OBJECTIVE. Extraosseous multiple myeloma is rare (< 5%) and has
not been systematically documented in the abdomen. Our aim is to catalogue and
describe the manifestations of multiple myeloma affecting abdominal
organs.
CONCLUSION. Extraosseous myeloma may involve multiple abdominal
organs and may mimic other malignancies. Clinicians and radiologists should be
aware of the potential for myeloma to involve extraosseous sites to avoid
unnecessary interventions when this occurs.
Introduction
Multiple myeloma is characterized by a proliferation of malignant plasma
cells originating in the bone marrow. The radiologic skeletal manifestations
of diffuse osteopenia or osteolytic bone lesions are well recognized.
Extraosseous myelomatous masses, however, are rare, found in less than 5% of
patients with multiple myeloma
[1]. They can arise in any
tissue, and their presence has been associated with more aggressive disease.
The purpose of this study was to document the different patterns of abdominal
extraosseous multiple myeloma.
Materials and Methods
We retrospectively reviewed the abdominal CT, MRI, and sonography reports
of all patients with multiple myeloma at our institution from 1998–2003
for extraosseous involvement. Twenty-nine patients with extraosseous disease
were found. All their images were reviewed to establish the extent and nature
of their abdominal abnormalities. The patients with masses in contiguity with
bony disease or concomitant lymphoma or amyloidosis were excluded. All
patients who did not have a biopsy of at least one extraosseous site of
disease were also excluded.
The study group comprised nine patients with a mean age of 54 years (range,
40–75 years). All patients were men and had multiple myeloma proven at
bone marrow biopsy. All but one patient had advanced clinical disease and had
received multiple courses of chemotherapy. The mean number of years with
disease was 1.8 years (range, 1–4 years).
Imaging included CT (n = 9) and sonography (n = 6). All
CT examinations were performed with MDCT scanners with 5-mm collimation and
were reconstructed at 50% intervals. IV contrast material was not administered
in three patients because of abnormal findings on renal function tests.
Sonograms included a standard technique for abdominopelvic evaluation. Two
patients underwent scrotal sonography. The cross-sectional studies of these
patients were reviewed by two abdominal radiologists by consensus; the site,
appearance, extent, and patterns of disease were recorded.
Approval for this study was obtained from our institutional research ethics
board. The need for an informed consent form from patients was waived by the
institutional research ethics board.
Results
Sixteen extraosseous myeloma deposits were identified in the nine patients.
The sites of involvement are summarized in
Table 1. In four (44%) of the
nine patients, more than one extraosseous site of disease was seen, whereas
the extraosseous disease was confined to one organ in five (56%) of the nine
patients. Soft-tissue masses ranged in size from 1 to 7.5 cm. All but two
patients had evidence of bony disease on imaging in addition to extraosseous
multiple myeloma.
Liver
The most commonly involved solid organ was the liver. We observed two
patterns of disease in the patients with hepatic involvement. Multiple focal
liver lesions varying in size from 1 to 6.5 cm were seen in two patients. On
sonography (n = 2), the lesions appeared hypoechoic in one patient
(Fig. 1A) and mixed in
echogenicity in the other patient. On unenhanced CT (n = 2) and
enhanced CT (n = 1), all lesions exhibited attenuation lower than
that of normal liver parenchyma, regardless of the phase of enhancement. In
one patient, diffuse liver disease was manifested by hepatomegaly without any
focal liver abnormality on CT. Liver biopsy showed diffuse tumor infiltration
of the parenchyma.
Genitourinary System
Although no renal parenchymal mass was seen, soft-tissue masses in the
perirenal spaces were seen in two patients (Figs.
1B,
1C, and
2). In two other patients,
multiple bilateral hypoechoic testicular lesions measuring up to 2.5 cm were
seen on sonography (Fig.
3).
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Fig. 1C. —48-year-old man with multiorgan involvement by multiple
myeloma. Unenhanced CT scan, which corresponds to B, shows bilateral
solid masses (arrowheads) in perirenal space with mass effect on
kidneys (asterisks).
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Fig. 2. —60-year-old man with multiple myeloma. Unenhanced CT scan
depicts left-sided perirenal and perihilar masses (arrowheads) that
are causing mild pelvocaliectasis. Multiple metastatic tumor nodules
(arrow) are visible in retroperitoneum.
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Pancreas
Multiple pancreatic masses were observed in one patient. The masses were
hypoattenuating on CT in this patient. A solitary pancreatic head mass was
seen in a second patient with pancreatic multiple myeloma on sonography and CT
(Fig. 4). Here, the mass
encased the adjacent vessels and was indistinguishable from pancreatic
adenocarcinoma on the basis of imaging findings.
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Fig. 4. —41-year-old man with multiple myeloma. Enhanced CT scan shows
large single myelomatous mass in head of pancreas causing mild dilatation of
pancreatic duct. Pancreas was only site of disease.
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Other Findings
One patient showed retroperitoneal lymphadenopathy. In another patient,
mesenteric masses, likely adenopathy, were seen. Another patient showed a huge
mass originating from the stomach, circumferentially surrounding and
thickening its walls (Fig. 5).
A spontaneous perforation of the stomach that required emergent surgery
occurred in one patient. Multiple peritoneal soft-tissue masses were observed
in one patient (Figs. 6A and
6B). Two patients had
subcutaneous soft-tissue masses on the abdominal wall
(Fig. 6B).
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Fig. 5. —48-year-old man with multiple myeloma. Enhanced CT scan shows
diffuse myelomatous infiltration of stomach causing gastric wall thickening
(arrowheads). Spontaneous perforation of stomach (asterisk)
was confirmed at surgery.
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Fig. 6A. —52-year-old man with peritoneal extraosseous multiple
myeloma. CT scan shows multiple enhancing soft-tissue nodules
(arrowheads) in peritoneal spaces outlined by ascites. Note studding
on gallbladder surface and also retroperitoneal tumor deposit by left
kidney.
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Fig. 6B. —52-year-old man with peritoneal extraosseous multiple
myeloma. CT scan shows tumor deposits at omentum and right paracolic gutter
(arrowheads) and at subcutaneous tissues of anterior abdominal wall
(arrow).
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Discussion
Extraosseous myeloma is an uncommon and aggressive form of multiple
myeloma. It is found in less than 5% of patients with myeloma
[1]. The most common
extraosseous site is the submucosal tissue of the upper airways. In pathology
articles of postmortem examinations, researchers have described extramedullary
multiple myeloma in the gastrointestinal tract, lymph nodes, spleen, parotid
gland, vagina, breast, pancreas, thyroid, and testicles
[2,
3]. Radiologic descriptions are
infrequent and include small numbers of patients and case reports. Because of
better therapy, including autologous bone marrow transplantation, patients may
be living longer with their disease and may reach advanced stages of the
disease less often.
Although extramedullary involvement of the liver is seen at autopsy in
28–50% of patients [3],
antemortem diagnosis is predominantly based on presumptive clinical and
laboratory findings without confirmatory radiologic findings. The imaging
appearances of hepatic multiple myeloma are nonspecific and variable based on
few published reports [4,
5]. Of the eight cases of
hepatic multiple myeloma reported in the literature, five exhibited a target
appearance on sonography
[4–6].
We did not observe this pattern in our series; instead, we noted hypoechoic
lesions in one patient and mixed-echogenicity masses in the another. The
appearance of hepatic multiple myeloma on CT is also variable, the only
constant finding being an absence of tumor calcifications
[4,
6,
7]. Mathieu et al.
[7] described a case in which
the dynamic CT findings of peripheral enhancement with gradual filling-in
toward the center of the lesion are similar to those encountered in patients
with cavernous hemangioma. However, all lesions seen in our study appeared as
hypoattenuating masses with little enhancement, similar to most of the cases
described in the literature
[6].
Renal disease is frequently encountered in patients with myeloma and
usually results from amyloidosis rather than plasma cell infiltration of the
kidneys [8]. Perinephric
masses, as seen in two of our patients, are an unusual extraosseous
manifestation of myeloma and have been reported in only one series
[6] and a recent case report
[9]. To our knowledge, only one
imaging report of testicular disease, seen as diffuse enlargement, has been
published in the literature
[6]. In our two patients,
multiple bilateral hypoechoic testicular lesions were noted. The pattern
described here is therefore unique, to our knowledge, and is indistinguishable
from the appearance of lymphoma, metastases, or sarcoidosis.
Multiple myeloma affecting the pancreas is extremely rare. We found few
previously reported cases of imaging features of pancreatic multiple myeloma,
which described a hypervascular mass simulating neuroendocrine tumor
[6] and multiple pancreatic
lesions [10]. We have observed
multiple pancreatic masses in one of our patients. An additional patient in
our series presented with a large solitary pancreatic head mass with vascular
involvement. The original radiologic diagnosis was pancreatic adenocarcinoma.
This patient did not have diagnosed myeloma, and percutaneous biopsy performed
before initiating palliative therapy showed a solitary plasmacytoma.
The myelomatous involvement of the gastrointestinal tract is well
documented in the pathology literature
[11], but reports of the
imaging are uncommon [12]. The
small bowel is the most involved organ, followed by the stomach and the colon.
The radiologic findings of gastric myeloma include diffuse gastric thickening
and the presence of infiltrative and polypoid mass lesions. Differentiation of
gastric myeloma and lymphoma on the basis of imaging findings is challenging.
Our patient developed a huge stomach mass with eventual spontaneous
perforation. However, early gastric myeloma could be invisible on imaging. In
our series, the CT appearance of the stomach was normal for an additional
patient with biopsy-proven stomach involvement.
In conclusion, our series presents a gamut of extraosseous findings in
multiple myeloma involving various abdominal organs. Clinicians and
radiologists should be aware of this occurrence so that extensive unnecessary
interventions can be avoided when extraosseous sites of disease are
encountered in a patient with systemic disease. Also to be recognized is the
unlikely possibility that a mass suggesting malignancy may be solitary
plasmacytoma.
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Abstract
Introduction
