AJR 2001; 176:783-788
© American Roentgen Ray Society
Imaging Findings in Pseudocystic Osteosarcoma
Murali Sundaram1,
William G. Totty2,
Michael Kyriakos3,
Douglas J. McDonald4 and
Kurt Merkel5
1
Department of Radiology, St. Louis University Health Sciences Center, 3635
Vista at Grand, St. Louis, MO 63110-0250.
2
Mallinckrodt Institute of Radiology, Washington University School of Medicine,
510 S. Kingshighway, St. Louis, MO 63110.
3
Department of Surgical Pathology, Washington University School of Medicine,
St. Louis, MO 63110.
4
Department of Orthopedic Surgery, Washington University School of Medicine,
St. Louis, MO 63110.
5
Department of Orthopedic Surgery, St. Louis University Health Sciences Center,
St. Louis, MO 63110-0250.
Received July 17, 2000;
accepted after revision August 21, 2000.
Address correspondence to M. Sundaram.
Abstract
OBJECTIVE. Our purpose was to describe four female patients with
osteosarcoma whose clinical and imaging findings primarily suggested either
simple or aneurysmal bone cyst. All lesions were osteolytic,
intracompartmental, and expanded bone without periosteal reaction. None of the
patients presented during the peak age incidence for osteosarcoma. From
imaging to histologic diagnosis, the discovery of osteosarcoma ranged from 1
week to 3 years.
CONCLUSION. Atypical osteosarcoma may rarely mimic simple or
aneurysmal bone cyst radiologically and may show a nonmalignant rate of
growth. It may be more frequently encountered in females and may not present
during the peak age incidence for osteosarcoma. Microscopically, the tumors
were not cystic, necrotic, or telangiectatic but were conventional
osteosarcoma and osteoclast-rich osteosarcoma.
Introduction
Osteosarcoma is the most common nonhematologic primary malignant tumor of
bone
[1,2,3,4].
The radiologic appearance of osteosarcoma is usually that of an aggressive
destructive lesion with a mixed osteolytic and sclerotic pattern and an
associated periosteal reaction and soft-tissue mass. Osteosarcoma, however,
may show considerable variability in its radiologic and histologic
appearances. A purely osteolytic form of osteosarcoma occurs in approximately
10% of all patients and is associated with a pattern of rapid growth
[5]. Telangiectatic
osteosarcoma, additionally, may have the appearance of an aneurysmal bone
cyst.
We present four female patients with osteolytic intracompartmental tumors
without a periosteal reaction or soft-tissue mass that radiographically
suggested either simple or aneurysmal bone cyst but microscopically proved to
be conventional osteosarcoma and osteoclastrich osteosarcoma.
Materials and Methods
Four female patients were identified in the past 5 years whose lesions,
based on age, location, and imaging findings, suggested simple or aneurysmal
bone cysts but radiologically proved to be osteosarcoma. Their ages were 3, 7,
26, and 34 years. All patients had radiographic studies, three had MR imaging,
and one had CT. Two of the osteosarcomas were in the proximal tibia; one, in
the femoral head and neck; and the fourth, in the navicular bone (Figs.
1A,1B,1C,1D,2A,2B,2C,2D,3A,3B,3C,3D,4A,4B,4C,4D).
Three patients were white, and one was black.
View larger version (82K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 1C. —Proximal tibial lesion in 7-year-old girl. Lateral radiograph
obtained 33 months after A and 36 months after B shows interval
growth of lesion. Note transverse fracture through middle of lesion. Minimal
callus bridges fracture line anteriorly, indicating that fracture is
subacute.
|
|
View larger version (71K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2A. —Tibial lesion in 3-year-old girl. Anteroposterior (A)
and lateral (B) radiographs of right leg, June1998, show well-defined
diametaphyseal osteolytic lesion of tibia with slight endosteal thinning.
Lesion is well marginated, and on lateral image, fracture is identified in
anterior cortex.
|
|
View larger version (73K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2B. —Tibial lesion in 3-year-old girl. Anteroposterior (A)
and lateral (B) radiographs of right leg, June1998, show well-defined
diametaphyseal osteolytic lesion of tibia with slight endosteal thinning.
Lesion is well marginated, and on lateral image, fracture is identified in
anterior cortex.
|
|
View larger version (69K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2C. —Tibial lesion in 30-year-old girl. Coronal (C) (TR/TE,
4500/96) and axial (D) (3500/119) MR images, 6 months after A
and B, confirm intracompartmental confines of tumor with aneurysmal
configuration.
|
|
View larger version (113K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 2D. —Tibial lesion in 3-year-old girl. Coronal (C) (TR/TE,
4500/96) and axial (D) (3500/119) MR images, 6 months after A
and B, confirm intracompartmental confines of tumor with aneurysmal
configuration.
|
|
View larger version (96K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3A. —34-year-old woman with eccentric osteolytic lesion in left
femoral head and neck. Anteroposterior radiograph of left hip shows
intracompartmental osteolytic lesion eccentrically located in femoral head and
proximal neck and extending to intertrochanteric line.
|
|
View larger version (102K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 3C. —34-year-old woman with eccentric osteolytic lesion in left
femoral head and neck. Axial CT scan of left hip joint reveals thin shell of
bone containing lesion superolaterally without soft-tissue mass or
intraosseous matrix.
|
|
View larger version (120K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4A. —26-year-old woman with lesion in tarsal navicular bone.
Coned-down anteroposterior (A) and oblique (B) radiographs of
mid foot show multilocular osteolytic lesion expanding tarsal navicular bone
medially with intact cortex.
|
|
View larger version (122K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4B. —26-year-old woman with lesion in tarsal navicular bone.
Coned-down anteroposterior (A) and oblique (B) radiographs of
mid foot show multilocular osteolytic lesion expanding tarsal navicular bone
medially with intact cortex.
|
|
View larger version (126K):
[in this window]
[in a new window]
[as a PowerPoint slide]
|
Fig. 4D. —26-year-old woman with lesion in tarsal navicular bone.
Fat-suppressed coronal MR image (4500/105) reveals no extraosseous mass. Tumor
has multilocular appearance with high signal intensity and fluid-fluid
levels.
|
|
Both children had large well-demarcated osteolytic lesions in the proximal
diametaphysis of the tibia that were initially interpreted as simple bone
cysts and on follow-up as aneurysmal bone cysts
(Figs.1A,1B,1C,1D
and
2A,2B,2C,2D).
The 7-year-old white girl, who was first seen in November 1995 and whose
lesion had been injected with steroids twice because of lack of regression
(Figs. 1A and
1B), presented 6 months after
her initial presentation with a fracture after an injury
(Fig. 1C). Because there was a
focal bump, CT was performed and showed the cortex intact without extraosseous
mass. IV contrast material showed enhancement of the tissue element in the
lesion thought to be inconsistent with a simple bone cyst and more likely to
represent an aneurysmal bone cyst (Fig.
1D). The 3-year-old black girl, who was first seen in June 1998
(Figs. 2A and
2B), had her leg placed in a
cast because of a fracture, and when her lesion was injected with steroids in
August 1998, aspiration yielded bloody fluid. Radiographs in November 1998
showed minimal change in the size of the lesion, and the diagnosis was changed
to aneurysmal bone cyst. MR imaging in December 1998 showed the lesion
expanded, occupying the proximal one third of the tibia with no evidence of an
extraosseous mass (Figs.2C and
2D). Both patients at this
point had open biopsies performed, and the diagnosis of conventional
osteosarcoma was made. They received chemotherapy, after which the 7-year-old
patient (Fig.
1A,1B,1C,1D)
was treated by a wide local excision of the tumor and reconstruction with
intercalary allograft. The 3-year-old patient (Fig.
2A,2B,2C,2D)
was treated by knee disarticulation in March 1999.
The two adult patients also presented with tumors in the lower extremity.
In the 34-year-old white woman, who presented with a 4-month history of left
hip pain, radiographs of the hip showed an eccentric osteolytic lesion
occupying the femoral neck and lateral aspect of the femoral head (Figs.
3A and
3B). The differential
diagnosis included giant cell tumor and aneurysmal bone cyst. CT showed the
lesion entirely osteolytic and intracompartmental, with an intact thin rim of
cortical bone superiorly and laterally
(Fig. 3C). MR imaging
(Fig. 3D) confirmed the
intracompartmental confines of the tumor. Frozen-section biopsy tissue was
histologically diagnosed as consistent with an aneurysmal bone cyst. The
femoral head and neck were then resected, and curettage of the trochanteric
extension was performed with a total hip arthroplasty reconstruction.
Histologically, the curetted material showed numerous collapsed cystic walls
and a few intact cystic spaces filled with blood. There were neither atypical
mitosis and destruction of bony trabecula at the perimeter nor infiltrative
growth. The histologic diagnosis was that of an aneurysmal bone cyst. Four
months after surgery, the patient developed an enlarging mass in her left
thigh. Radiographs showed extensive local recurrence in the proximal femur
around the arthroplasty and diffuse bilateral metastatic pulmonary disease.
Histologic sections of tissue obtained from open biopsy of the mass showed
areas characteristic of aneurysmal bone cysts, but sections of the more
ossified tumor tissue showed solid areas with abundant osteoid and bone
production. These areas merged with an atypical chondroid and spindle cell
stroma. Separate foci of atypical chondroid stroma believed to be part of the
lesion, rather than reactive callus, were seen. These latter patterns were
believed to represent features of a conventional osteosarcoma. Review of the
prior biopsy tissue failed to show any cartilage or atypical stroma. The
patient was treated with chemotherapy.
The fourth patient in this series is a 26-year-old woman who presented with
a 1-year history of pain and swelling in the medial aspect of her right mid
foot. Radiographs of the foot showed the medial half of the navicular bone
expanded by a multilocular osteolytic lesion with thinning of the cortex. The
presumptive radiologic diagnosis was aneurysmal bone cyst (Figs.
4A and
4B). MR imaging on coronal and
sagittal T1-weighted sequences revealed nearly complete replacement of the
navicular bone by tumor, and on T2-weighted sequences, the lesion was
multilocular with fluid—fluid levels (Figs.
4C and
4D). Curettage with bone
grafting was performed. Histologic examination of the curettage specimen
revealed isolated cystic blood spaces whose walls contained atypical stromal
cells with abundant mitotic figures and islands of osteoid produced by these
cells. A diagnosis of telangiectatic osteosarcoma was made. The patient
received a 3-month course of chemotherapy after which the navicular, talus,
and medial cuneiform bones were resected and the foot was reconstructed with a
segment of iliac crest and allograft. Histologically, the tumor contained
areas indistinguishable from benign giant cell tumor with nodular areas of
benign osteoclast-type giant cells. Anaplastic stromal cells and
multinucleated giant tumor cells with anaplastic pleomorphic nuclei populated
other areas. Stromal spindle cells in storiform pattern and numerous highly
atypical mitotic figures were present. Osteoid formation by malignant stromal
cells was evident. Only a rare aneurysmal blood space was found. The tumor was
confined to the navicular bone. A diagnosis of osteoclast-rich osteosarcoma
with focal aneurysmal bone cyst-like areas was made.
Results
From imaging to histologic diagnosis, the discovery of osteosarcoma ranged
from 1 week to 3 years. Three patients had conventional osteosarcoma, and one,
an osteoclastrich osteosarcoma. All lesions were osteolytic,
intracompartmental, and expanded bone without periosteal reaction. In one
patient, the tumor remained intracompartmental for 3 years before the
diagnosis was made (Fig.
1A,1B,1C,1D).
In another, the lesion did not significantly change for 6 months after a
pathologic fracture through the lesion (Fig.
2A,2B,2C,2D).
In three patients, diagnosis of osteosarcoma was made at the time of biopsy,
whereas in one patient, an initial diagnosis of aneurysmal bone cyst was made
after curettage (Fig.
3A,3B,3C,3D).
This patient subsequently developed metastases and died. The two children are
disease-free 20 and 17 months postoperatively. The patient with an
osteosarcoma in the tarsal navicular bone was disease-free 14 months
postoperatively (Fig.
4A,4B,4C,4D).
Discussion
Osteosarcoma is the most common nonhematologic primary malignant tumor of
bone whose peak age incidence is usually from 15 to 20 years old with a 2:1
male predominance
[1,2,3,4].
Most conventional osteosarcomas have a mixed lytic and sclerotic radiographic
pattern, reflecting the type of tissue or matrix in the tumor. Purely
osteolytic lesions are uncommon, accounting for approximately 10% of all
patients and usually encompassing the fibroblastic, fibrohistiocytic,
telangiectatic, or giant cell-rich forms of the tumor
[1,2,3,4].
Except for the subtype of low-grade well-differentiated osteosarcoma, purely
lytic osteosarcoma has been associated with a pattern of rapid growth
[5]. Low-grade osteosarcomas,
however, in greater than 50% of the patients, have a soft-tissue mass, and
most show poor margination [3].
Mirra [4] indicated that 80% of
osteosarcomas will have a periosteal reaction, and even slow growing or
low-grade lesions, which he describes as "incipient," will, on CT
or MR imaging, show a soft-tissue mass.
All our patients were female, and none were within the peak age of
incidence for osteosarcoma. Two were younger than 10 years old, an uncommon
age for osteosarcoma. In the Mayo Clinic series of 1649 osteosarcomas, only
seven patients were younger than 10 years old, six of whom were girls
[3]. The radiographic features
common to all our patients were the intracompartmental location of the tumor,
a purely osteolytic pattern, and an absence of a periosteal reaction or
soft-tissue mass. In all patients, the involved bone was expanded, with
variably thinned endosteum and without a cortical breech (Figs.
1A,1B,1C,1D,2A,2B,2C,2D,3A,3B,3C,3D,4A,4B,4C,4D).
The radiologic interpretation of the imaging features was influenced by the
age of patients and the location of the lesions so that simple bone cyst or
aneurysmal bone cyst was considered the most likely diagnosis in three
patients, whereas giant cell tumor was favored over aneurysmal bone cyst in
one patient. Three of the tumors were conventional osteosarcomas, and one, a
giant cell—rich variant of osteosarcoma with focal aneurysmal bone
cystlike areas. In three patients, the diagnosis of osteosarcoma was initially
made on examination of both biopsy sample and the resection specimen. In the
other patient, tissue was diagnosed as an aneurysmal bone cyst. However, when
this patient returned with pulmonary metastases, the rebiopsy tissue showed
not only features identical to those in the original biopsy sample but also
small areas of conventional osteosarcoma. The tumor in the navicular bone was
originally diagnosed as telangiectatic osteosarcoma on biopsy tissue, but the
diagnosis was changed to osteoclast-rich osteosarcoma after examination of the
resected tumor.
The tumors in both children showed relatively indolent rates of growth for
osteolytic osteosarcomas. In the 7-year-old child (Fig.
1A,1B,1C,1D),
the tumor did not change its appearance over a 3-year period, and when the
diagnosis of osteosarcoma was finally made, there was no evidence of
metastatic disease. This patient, whose tumor was first observed almost 5
years ago, remains disease-free. In the 3-year-old child, the initial
presumptive diagnosis of a simple bone cyst was changed to an aneurysmal bone
cyst when an aspirate of the lesion, 3 months after it was first observed,
yielded bloody fluid. Six months after the lesion was initially discovered, MR
images showed no evidence of a soft-tissue mass (Figs.
2C and
2D).
Both patients' imaging studies would fit the characterization by Mirra
[4] of "incipient"
osteosarcomas, because neither of the lesions showed any of the described
features associated with osteosarcoma, and despite the relatively indolent
rates of growth, the tumors were conventional and not low-grade osteosarcoma.
In both patients, a radiologic diagnosis of solitary bone cyst was considered
most likely. However, the tibia, the location of both tumors, appeared to be
an uncommon location for simple bone cysts. In the Netherlands' Bone Tumor
Registry [6], of 209 simple
bone cysts, only nine were so located. Of the nine cysts, only five were in
the proximal tibia.
The age of the patient with an eccentric location of the lesion in the
femoral head and neck favored a diagnosis of giant cell tumor rather than
aneurysmal bone cyst, but the tissue was thought to be aneurysmal bone cyst.
When this patient developed metastatic disease, the most likely source of
error was a telangiectatic osteosarcoma mistakenly diagnosed as an aneurysmal
bone cyst. Although the recurrent tumor also showed features of aneurysmal
bone cyst, solid areas of conventional osteosarcoma were present. Review of
the prior biopsy tissue failed to show such areas. Location of osteosarcoma in
the femoral head and neck is distinctly uncommon, constituting less than 1% of
all osteosarcomas in four large series
[1,2,3,4].
In the patient with a lesion in the tarsal navicular bone, the imaging
features of an expanded osteolytic lesion with thinning of the endosteum and
fluid—fluid levels suggested aneurysmal bone cyst. There was no
soft-tissue mass. Although histologic examination of this lesion suggested a
diagnosis of telangiectatic osteosarcoma, the resected tumor showed an
osteoclastrich osteosarcoma with only rare aneurysmal blood spaces. This
patient appears to be the first one with osteoclast-rich osteosarcoma in a
foot bone [7]. Osteosarcoma of
any type in a foot bone is an exceptional occurrence. Of 1929 cases of
osteosarcoma at the Rizzoli Institute (Bologna, Italy), only 12 tumors (0.6%)
were in the foot, none of which were in the navicular bone
[8]. By contrast, the
occurrence of aneurysmal bone cyst in the small bones of the hands and feet is
significantly higher, with an incidence ranging from 9% to 12%
[9,
10]. In a recent review of 52
foot osteosarcomas by Choong et al.
[11], the radiologic patterns
were consistent with conventional osteosarcoma, and all cases were associated
with a soft-tissue mass. The calcaneus was the most commonly involved bone,
with the navicular bone involved in only two cases.
Even in retrospect, our patients do not lend themselves to a presumptive
diagnosis of osteosarcoma. Because simple bone cysts and aneurysmal bone cysts
were the primary diagnostic considerations in this group of patients, we have
elected to collectively describe these cysts as "pseudocystic"
osteosarcoma.
Our series is too small to make any determinations about the relationship
of the described atypical features to clinical outcome. In this subset of
patients, the unpredictability of the disease is underscored by the extremes
of outcome in two of our patients who did not initially receive optimal
treatment. One patient was untreated for 3 years and remains alive and well,
whereas another developed metastatic disease 4 months after presentation and
died 13 months later. We could not identify a similar series of osteosarcoma
with a pseudocystic radiologic appearance, although it has been stated,
without references or illustrations, that rarely does osteosarcoma have such
an appearance [1,
3]. A pictorial essay reviewing
subtle, rare, and misleading radiologic appearances of osteosarcomas did not
have cases similar to those reported in our study
[12]. To determine the
incidence and prognostic significance, if any, of the imaging and other
associated atypical features of osteosarcoma described herein, a review of a
significantly larger series is required.
Acknowledgments
We appreciate the considerable secretarial assistance of Lois Hebel in the
preparation of this manuscript.
References
-
Dorfman HD, Czerniak B. Osteosarcoma. In: Dorfman HD, Czerniak B,
eds. Bone tumors. St. Louis: Mosby,
1998: 128-152
-
Mulder JD, Schütte HE, Kroon HM,
Taconis WK. Intraosseous osteosarcoma. In: Mulder JD,
Schütte HE, Kroon HM, Taconis WK, eds.
Radiologic atlas of bone tumors. Amsterdam: Elsevier,
1993: 51-53
-
Unni KK. Osteosarcoma. In: Unni KK, ed. Dahlin's bone
tumors, 5th ed. New York: Lippincott-Raven,
1996: 143-183
-
Mirra JM. Osseous tumors of intramedullary origin. In: Mirra JM,
ed. Bone tumors, vol. 1.
Philadelphia: Lea & Febiger, 1989:250
-289
-
DeSantos LA, Edeiken B. Purely lytic osteosarcoma.
Skeletal Radiol
1982;9:1
-7[Medline]
-
Mulder JD, Schütte HE, Kroon HM,
Taconis WK. Solitary bone cyst. In: Mulder JD,
Schütte HE, Kroon HM, Taconis WK, eds.
Radiologic atlas of bone tumors. Amsterdam: Elsevier,
1993: 579-581
-
Ostrowski, ML, Spjut HJ. Lesions of the bones of the hands and
feet. Am J Surg Pathol
1997;21:676
-690[Medline]
-
Biscaglia B, Gasbarrini A, Bohling T, Bacchini P, Bertoni F, Picci
I. Osteosarcoma of the bones of the foot: an easily misdiagnosed malignant
tumor. Mayo Clin Proc
1998;73:842
-847[Medline]
-
Mulder JD, Schütte HE, Kroon HM,
Taconis WK. Aneurysmal bone cyst. In: Mulder JD,
Schütte HE, Kroon HM, Taconis WK, eds.
Radiologic atlas of bone tumors. Amsterdam: Elsevier,
1993: 557-577
-
Dahlin DC, McLeod RA. Aneurysmal bone cyst and other non-neoplastic
conditions. Skeletal Radiol
1982;8:243
-250[Medline]
-
Choong PFM, Quereshi AA, Sim FH, Unni KK. Osteosarcoma of the foot:
a review of 52 patients at the Mayo Clinic. Acta Orthop
Scand 1999;4:361
-364
-
Rosenberg ZS, Lev S, Schmahmann S, Steiner GC, Beltran J, Present
D. Osteosarcoma: subtle, rare, and misleading plain film features.
AJR
1995;165:1209
-1214[Abstract/Free Full Text]
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
This article has been cited by other articles:
|
|
|
|
 
H. S. Cho, J. H. Oh, H.-S. Kim, H. G. Kang, and S. H. Lee
Unicameral bone cysts: A COMPARISON OF INJECTION OF STEROID AND GRAFTING WITH AUTOLOGOUS BONE MARROW
J Bone Joint Surg Br,
February 1, 2007;
89-B(2):
222 - 226.
[Abstract]
[Full Text]
[PDF]
|
|
|
|
|
|
|
P. T. Liu, S. D. Valadez, F. S. Chivers, C. C. Roberts, and C. P. Beauchamp
Anatomically Based Guidelines for Core Needle Biopsy of Bone Tumors: Implications for Limb-sparing Surgery
RadioGraphics,
January 1, 2007;
27(1):
189 - 205.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
