Athirty-eight-year-old man with von Recklinghausen disease was
admitted to our institution because of pain localized in the distal part of
the left thigh. The patient had manifestations of type-1 neurofibromatosis,
including café-au-lait spots and osseous lesions since
childhood (Fig. 1). Physical
examination revealed localized tenderness at the anterior aspect of the distal
part of the left thigh. There was no palpable mass, and routine laboratory
data were normal. Anteroposterior and lateral plain radiographs revealed a
large destructive lytic lesion in the distal part of the left femur with
thinning and erosion of the posterior cortex
(Fig. 2).
A bone scan showed increased radioisotope uptake in the distal part of the
left femur. There was also increased radioisotope uptake in the proximal parts
of both tibiae, which was attributed to the existing skeletal
neurofibromatosis lesions.
Computed tomography showed a large osteolytic lesion in the distal part of
the femoral diaphysis and the distal femoral metaphysis, with erosion of the
posterior and anterior cortices and medial extension into the vastus medialis.
Magnetic resonance imaging of the left thigh revealed an extensive, permeative
lesion in the distal metaphyseal-diaphyseal region of the left femur, with
erosion of the posterior cortex associated with a soft-tissue mass
(Fig. 3).
Computed tomography-guided fine-needle aspiration was performed, but the
specimen obtained was not diagnostic and cultures of the specimen were
negative. Computed tomography of the chest also revealed negative
findings.
Histological examination of tissue obtained at a subsequent open biopsy
revealed findings suggestive of a sarcoma, probably a malignant fibrous
histiocytoma of bone. Wide resection of the tumor, including 20 cm of the
distal part of the femur and the surrounding soft-tissue envelope, was
performed. After the resection, a modular distal femoral replacement
prosthesis (MRS System; Stryker/Howmedica, Mahwah, New Jersey) was used for
the reconstruction and restoration of the knee joint. A local gastrocnemius
muscle flap provided adequate coverage over the reconstruction.
Gross examination of the specimen showed an 8 × 7 × 4-cm mass
in the distal femoral metaphysis and epiphysis, with both cystic and solid
areas, eroding the cortex and extending to the surrounding soft tissues.
Histological examination revealed a high-grade malignant bone tumor with
features suggestive of a malignant fibrous histiocytoma of bone, without any
areas with morphologic features of fibroma or neurofibroma
(Fig. 4). The margins of the
resection and two regional lymph nodes were free of tumor.
Postoperatively, the patient was treated with six cycles of chemotherapy (a
combination of Adriamycin [doxorubicin], ifosfamide, and cis-platinum). At the
time of the last follow-up, eighteen months postoperatively, the patient was
alive with no local recurrence or distant metastases. Although there was
slight quadriceps muscle weakness, the functional result was satisfactory,
with a knee range of motion of 0° to 90°
(Fig. 5).