A 76-year-old man with prostatic enlargement presented with a single episode of painless gross hematuria. He had been seen regularly for several years in urology for minimally obstructive voiding dynamics. His medications included furosemide. He was scheduled for an intravenous urogram (IVU).
A 40-year-old female presented with a bacterial skin infection
and was treated with antibiotics and corticosteroids. While being
examined in the department, the patient underwent bone scintigraphy
to evaluate excruciating acute right hip pain. On three-phase bone
scintigraphy, blood pool images demonstrated a prominent abnormal
focal area of increased soft-tissue uptake in the right hip
joint/groin region. The delayed static images showed subtle,
minimally greater activity in the distribution of the right hip's
greater trochanter, but no prominent intense focal lesion was
present. A right hip X-ray showed a bone cyst; subsequently, she
was admitted because of concerns she might sustain a hip fracture.
Pelvic MR imaging revealed an aggressive soft-tissue mass along the
medial aspect of the right hip joint that involved multiple muscle
groups in the right upper thigh and groin. A CT-guided core biopsy
of the right thigh mass was performed.
On the whole-body scan, there was nonspecific increase in
activity in the right hip joint region (figures 1,2). Blood pool
images showed a moderate increase in radiotracer activity in the
same region, suggestive of a large soft-tissue mass in the right
hip joint and groin (figure 3). Because of these findings, an MRI
of the pelvis and upper thighs was obtained (figures 4,5). This
showed a poorly circumscribed, heterogenous soft-tissue mass
involving multiple muscle groups, including the right obturator
externus, quadratus femoris, adductor magnus, and brevis. The mass
extended through the right obturator foramen and involved or
displaced the undersurface of the gluteus maximus. The
heterogeneous signal intensity varied between the T1- (figure 4)
and T2-weighted (figure 5) images and suggested a component of
internal hemorrhage within the mass. A CT-guided core biopsy of the
right thigh mass was then performed.
The resulting surgical pathology report described a moderately
cellular proliferation of synovial-like and histiocytic cells which
stained positive for iron and negative for cytokeratin; this was
consistent with a diagnosis of pigmented villonodular synovitis
(PVNS). The differential diagnosis of this disorder includes benign
xanthoma, xanthogranuloma, giant-cell tumor of the tendon sheath,
dermatofibroma, fibrous neoplasms, and sclerosing hemangioma (table
1). Other tumors considered, though less likely, were
undifferentiated liposarcoma, soft-tissue chondrosarcoma, and
leiomyosarcoma. The patient underwent surgical resection of the
soft-tissue mass, and bone graft and internal fixation of the right
PVNS is a benign tumor of histiocytic origin (table 1) which may
occur in a localized or diffuse form. The localized form has
identical histology to giant-cell tumor of the tendon sheath. The
diffuse form is histologically identical to the localized form but
involves the entire synovium. The diffuse form most commonly
affects the knee, but the hip, ankle, shoulder, wrist, and other
joints also can be involved.
PVNS, primarily a disease of young adults, is more common in
males. Patients may complain of joint stiffness, pain, or swelling,
usually intermittent, in the involved joint region. A mass may be
palpable, and joint aspiration characteristically reveals
Osseous changes are the result of pressure atrophy, actual
invasion of the bone, or both. Subchondral bone erosion, with or
without irregular cyst-like radiolucent defects, is an important
roentgenic finding which may mimic T.B. or rheumatoid arthritis on
The main differential diagnosis of PVNS is degenerative or
traumatic arthritis and is based upon its nonarticular character.
When no history of trauma exists, the physician should be alerted
to the proper diagnosis. Bone involvement is best demonstrated on
CT, while MRI will show the soft mass associated with this lesion
to the best advantage. Three-phase bone scintigraphy, as was
initially performed in this case, may show a localized increase in
the vascular flow and increased soft-tissue uptake in the affected
area during the blood pool phase. This study also may show
increased uptake in the involved bone on the delayed whole-body
In summary, PVNS is a rare benign tumor of histiocytic origin.
This soft-tissue lesion can be suggested by three-phase bone
scintigraphy and MRI in the appropriate clinical setup. Treatment
usually involves surgical excision and bone reconstruction of the
involved joints. Synovectomy and radiotherapy is indicated if
surgery fails to control the process.
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and Their Application, pp 320-321. Philadelphia, JB Lippincott,
2. Crenshaw AH: Campbell's Operative Orthopedics, pp 305-306.
St. Louis, Mosby, 1992.
3. Salter RB: Textbook of Disorders and Injuries of the
Musculoskeletal System, pp 346-347. Baltimore, Williams &
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Medicine, ed 2, pp 986-1026. Philadelphia, WB Saunders, 1995.
5. Thrall JH, Ziessman HA: Nuclear Medicine, The Requisites, pp
93-128. St. Louis, Mosby, 1995.
6. Edeiken J, Hodes PJ: Roentgen diagnosis of disease of bone,
pp 6481-6487. Baltimore, Williams & Wilkins, 1967.
7. Putman CE, Ravin AC: Textbook of Diagnostic Imaging, p 1625.
Philadelphia, WB Saunders, 1998.
Prepared by Amir Salmanzadeh MD, William Beaumont Hospital,
Royal Oak, MI; Stephen J. Pomeranz, MD, and Parshan S. Ramsingh,
MD, Department of Nuclear Medicine, The Christ Hospital,