During a soccer game in June 1993, a nineteen-year-old man
experienced an indirect injury to the right knee that caused a rupture of the
anterior cruciate ligament. A magnetic resonance imaging scan confirmed the
diagnosis. An arthroscopic reconstruction of the anterior cruciate ligament
was carried out in October 1993 with use of the patellar tendon.
Stainless-steel (alloy-316L) screws (with a diameter of 6.5 mm) were used for
the femoral and tibial fixation. The rest of the intra-articular examination
was normal, and the postoperative course was uneventful. In 1995, a
hemarthrosis developed in the right knee subsequent to a new injury. The knee
was stable, and the hemarthrosis resolved with symptomatic treatment. In 1997,
the patient experienced a locking episode of the right knee, which was found
to be caused by a bucket-handle tear of the medial meniscus at arthroscopy.
The torn meniscus was resected. The remainder of the examination was normal,
and there were no postoperative complications. Two years later, the patient
presented with a painless mass that was adherent to the scar on the medial
side of the knee but mobile with regard to the deep surface
(Fig. 1). This lesion had
doubled in volume within the previous two months. The knee was stable and
without effusion. Radiographs demonstrated normal findings
(Fig. 2). A magnetic resonance
imaging scan showed an extra-articular, heterogeneous tissue mass, 3.5 ×
5.8 × 4.7 cm in size, that enhanced after gadolinium injection
(Fig. 3). The lesion came in
contact with the capsule but did not appear to invade the knee joint. No
effusion was seen. This lesion was in contact with the patellar tendon. No
osseous reaction was observed. A technetium-99 bone scan was negative, and
computerized tomography of the lung did not reveal any sign of metastasis. A
biopsy specimen was obtained, leading to the diagnosis of grade-2 pleomorphic
malignant fibrous histiocytoma, according to the system of the Federation
Nationale des Centres de Lutte Contre le
Cancer40.
En bloc resection of the tumor and surrounding tissues was performed,
removing the scar on the anteromedial aspect of the knee and the previous scar
from the site where the graft had been harvested, the medial third of the
patellar ligament, the anteromedial capsule, the anterior portion of the
medial meniscus, and the anteromedial tibial periosteum. A medial
gastrocnemius muscle flap was sutured to the patellar tendon and to the
remaining capsule to cover the tissue loss. A split-thickness skin graft
completed the procedure.
Gross inspection of the resected specimen showed a 7 × 6 × 4-cm
tumor located outside the anterior knee capsule, closely associated with the
previous scars, and all specimen margins passed through normal tissue. A
nonresorbable suture was included in the mass. Histological analysis revealed
a proliferation of tumor cells with marked cytological and nuclear
pleomorphism, often with bizarre tumor giant cells admixed with spindle cells
and rounded histiocyte-like cells (Fig.
4). The mitosis rate was eleven mitoses per ten high-power fields,
and there were focal areas of necrosis. Tumor cells were stained only with
antibodies to vimentin without evidence of other differentiation. Scanning
electron microscopy with energy dispersive x-ray spectroscopy showed rare
particles containing chromium and iron (Figs.
5-A and
5-B).
Considering that the tumor was grade 2, chemotherapy with doxorubicin (six
courses) and radiotherapy (60 Gy) was undertaken. Chemotherapy was interrupted
after the second course, however, because of a local infection. At the time of
the three-year follow-up, the patient had resumed his occupational activities
as a forklift truck driver and walked without a cane. There was no sign of
local recurrence or metastatic dissemination.
Three tables presenting previously published case reports of malignant
fibrous histiocytoma arising after prosthesis implantation, osteosynthesis, or
in scars are available with the electronic versions of this article, on our
web site at
(go to
the article citation and click on "Supplementary Material"), and
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