A 26-year-old male presented with a two-year history of vague discomfort about the hip.
[X-Ray] A-P radiograph of the pelvis. There is a well marginated radiolucent lesion in the inferior portion of the femoral neck.
[X-Ray] Magnified A-P view of the proximal left femur.The lesion is less dense than the trabecular bone in the adjacent pubic rami but more dense than the adjacent soft tissues.
[X-Ray] Magnified lateral view of the proximal left femur. The density is homogenous rather than heterogenous and clearly resembles "ground glass". The differential would include a healing simple cyst, fibrous dysplasia, aneurysmal bone cyst and osteblastoma.
[Iso-Scan] Regional isotope scan of the left hip area. There is an intense focal uptake of isotope indicating an active process confined with in the radiographic extent.
[CT Scan] Axial CT image cut through the left femoral head and neck. The image clearly deliniates the difference in radiodensity between the pattern of normal trabecular bone and the homogenous immature mineralized density with in the lesion.
[MRI] Axial T-1 weighted MRI cut through the left femoral head and neck. The lesion has a low intensity signal indicating a l ow water content in th e lesional tissue - i.e. collagen or bone matrix rather than fluid or cartilaginous matrix.
[MRI] Axial T-2 weighted MRI cut through the left femoral head and neck. The T-2 weighted image has a moderately brighter signal indicating tissue with significant vascularity.
A trocar biopsy of the lesion was done.
[Micro] A panoramic field from the biopsy specimen. The field is composed of many immature trabeculae of bone arranged in a non-stress oriented pattern. Many have no connection to their neigh bors but exist as isomlated bits of immature bone. The normal marrow has been replaced by sheets of immature fibrous connective tissue.
[Micro] A medium power field from the interior of the lesion. This field contains several lightly stained immature trabeculae with no internal cement lines that are indicative of continuning maturation or remodeling. The free edges of the trabeculae are lined with immature fibroblasts rather than the large plump hyperchromatic osteoblasts ususlly seen about immature newly formed traeculae.
[Micro] A high power field from the previous field. Greater magnification shows the immature dysplastic mesenchymal cells producing wisps of faintly staining collagen that filled the intertrabecular areas. These together with the immature dysplastic trabeculae form the typical pattern of fibrous dysplasia.
Diagnosis: Fibrous Dysplasia
MSTS Stage: Non-applicable
Treatment: Insertion of a cortical allogeneic graft without extensive curettage.
A 7 y/o female presented with pain and limp about the hip.
[X-Ray] An AP radiograph of the hip at presentation. There is a large radiolucent lesion extending from the midportion of the iliac wing to the subchondral plate of the acetabulum with questionable destruction of the subchondral plate at the dome of the acetabulum.
A bone scan showed no other lesions. Without further staging a biopsy was done.
[Gross Path] The curettings from the biopsy. The tissue was soft, buttery yellow, with little vascularity. The texture, vascularity and yellowish color are more suggestive of inflammatory rather than neoplastic tissue.
[Micro] A low power field from the curettings. This field contains a sheet of cells with virtually no matrix of any kind. This is more consistent with inflammation or marrow cell neoplasms rather than neoplasms arising from the mesenchymal elements of bone.
[Micro] A high power field from the same tissue. The cells are randomly scattered about the field and seperated from each other by clear areas again suggestive of an inflammatory process rather than the densely packed cellular pattern of neoplastic tissue. The majority of the small round cells have heavily basophilic nucleii with little or no cytoplam. Several however have bi- and trilobed nucleii (upper left quadrant) and a suggestion at this magnification of eosinophilic cytiplasm. Randomly distributed through out the tissue are much larger, pale staining cells with large nucleii, a distinct nuclear membrane and prominent nucleoli (central area) suggestive of histiocytes.
[Micro] Magnification of the previous field. Along the margins of the field are cells with multilobed nucleii and distinctive eosinophilic cytoplasm - eosinophiles. In between them are much larger pale staining cells with multiple small clear vacuoles in thier cytoplasm and large faintly basophilic nucleii with a distinct nuclear membrane - histiocytes.
Diagnosis: Eosinophilic Granuloma.
Stage: Non applicable
Treatment: Curettage/allogeneic bone grafting. Although these lesions often heal spontaneously the size and risk of deformation of the acetabulum makes bone grafting following curettage the preferred treatment. The size of the lesion makes allogeneic banked bone preferrable over autogenous bone.
Follow-up:
[X-Ray] An AP radiograph 2 yrs post allogeneic bone grafting. The child was asymptomatic.
A 21-year-old male presented with a three-month history of low-back pain and urinary incontinence.
[X-Ray] AP radiograph of the pelvis. There is a radiolucent lesion involving the majority of the sacrum. The lesion appears compartmentalized by thin septae of reactive bone. The epicenter of the lesion is the midline, suggestive of chordoma.
[X-Ray] AP sacral cone-down view. This view brings out the fine septae of reactive bone and suggests a soft tissue component beyond the reactive rim.
[Iso-Scan] Late phase of the regional isotope scan. There is a modest increase in isotope uptake within the radiographic confines of the lesion. Such unexpectedly modest uptake is suggestive of myeloma.
[CT Scan] A first generation axial CT image at the proximal sacral level. In this primitive image at this level the lesion protrudes anteriorly and appears to be seperated from the large bladder by a thin line of radiolucent fat.
[CT Scan] Axial CT image at the midsacral level. At this level the lesion extends less anteriorly and the distinction between it and the large bladder is more apparent.
An open biopsy was done from a posterior midline approach.
[Surgical Path] The tissue was soft, reddish brown in color with occasional yellowish nodules. The tissue appears quite vascular and its soft texture consistent with either chordoma or myeloma.
[Micro] A panoramic view from the periphery of the lesion. The field is composed entirely of cellular tissue with no mesenchymal matrix. Even at this power there appear to be a significant number of darker staining giant cells.
[Micro] A panoramic view from the central portion of the lesion. The tissue from the central portion of the mass appears the same as that from the periphery.
[Micro] A low power field from the the central panoramic field. There is a monotonous repititous pattern of giant cells throughout the field. They appear of uniform size and are evenly distibuted throughout the field.
[Micro] A medium power field from the previous low power field. The oval stromal cells produce no matrix. Their nucleii have a distinct nuclear membrane, asre vaculated, and contain darkly stained nucleoli. The nucleii of the giant cells have the same nuclear characteristics.
[Micro] Another medium power field from the previous low power field. This field is predominately composed of masses of uniformly small giant cells. Again the similarity of the nucleii of the oval stromal cells and those of the giant cells is quite striking.
[Micro] A high power field from the first medium power field. The central portion of the field is filled by a multinucleated giant cell with eosinophilic cytoplasm containing fine clear vacuoles. The surrounding mononuclear stromal cells have nucleii withe the identical features of the nucleii in the giant cell. At the eleven o'clock position about the giant cell there is a smaller multinucleated cell with four nucleii that appears to have formed by a coalition of single-nucleated stromal cells.
[Micro] A high power field from the second medium power field. Here again is a single large giant cell surrounded by similar appearing mononuclear stromal cells. Note the golden brown color of hemosiderin in the stromal cell in the lower right corner of the field.
Despite the radiographic location suggestive of chordoma and the isotope uptake pattern of meloma the histologic features are thoose of a giant cell tumor. The large size with deformation of the sacral body, the soft tissue extension anteriorly, and the signs of neurological involvement clinically all indicate, despite the benign histologic appearance, an aggressive process. Because of the significant neurologic morbidity of the necessary wide en bloc margin and the uncertainty of attaining an adquate margin, definitive radiation therapy was deemed the more prudent treatment.
Diagnosis: Giant Cell Tumor
Stage: 3
Treatment: Definitive Radiation Therapy
A 14 yr. old female presented with 6 mos. history of right lower quadrant abdominal discomfort and the recent recognition of a hard pelvic mass.
[X-Ray] AP radiograph of the pelvis 4 mos. prior to presentation. There is a poorly delineated increase in density in the medial proximal porion of the ilium adjacent to the sacroiliac joint.
[X-Ray] AP radiograph of the pelvis at presentation. At this time the area of increased density is more apparent and appears to be protruding intrapelvically just below the sacroiliac joint. The radiodensity has a flocculent pattern suggstive of neoplastic bone.
[Iso-Scan] A staging total body isotope scan. Both the anterior and posterior images show intense diffuse increase in isotope activity in the entire iliac wing extending well beyond the radiographic limits of the lesion.
[CT Scan] Axial CT scan cut through the midportion of the mass. A large mass is seen arising from the pelvic aspect of the ilium. The deeper portions of the mass contain areas of amorphus mineralization while the peripheral aspect has the dernsity of adjacent soft parts.There is significant medial dislacement of the iliac neurovascular bundle.
[CT Scan] Axial CT scan with contrast. The deeper portion of the mass is markedly enhanced indicating pathologic hypervascularity. The contrast in the iliac vessels show the extent of their displacement and the deformation of the intervening psoas muscle.
[MRI] Axial T-1 weighted MRI image cut through the midportion of the mass. The mass has a low intensity homoogenous signal. There is involvement of the medial cortex of the ilium with extension into the interior of the ilium.
An open biopsy of the periphery of the intrapelvic soft tissue extension was done.
[Micro] A panoramic field from the biopsy specimen. The field is composed of hyperchromatic, pleomorphic cells surrounnded by thin bars of eosinomphilic amorphus trabeculae of bone highly suggestive of a bone forming neoplasm.
[Micro] A representative field from the interior of the specimen. In this field the irreglarly arranged trabeculae are more deeply stained and represent tissue from the mineralized portions of the mass. The absence of the usual intercon necting pattern of cancellous bone is typical of neoplastic bone formation.
[Micro] A medium power field from the periphery. At this power the hyperchromaticity and pleomorphic pattern of the lesional cells is very apparent. The intervening lightly stained osteoid varies from large amorphus blobs to fine cobweb-like encasement of individual cells - typical of classic osteosarcoma.
[Micro] A high power field from the previous medium power field. The cell just to the left of center in this field has an abnormal mitrosis. Another is seen along the upper right margin of the field - both indicative that this is a classic high grade osteosarcoma.
Diagnosis: Osteosarcoma
Stage: II B
Treatment: Preoperative chemotherapy and with a satisfactory response a wide internal hem ipelvectomy, followed by postoperative chemotherapy
An 18-year-old female presented two months after the onset of shoulder pain with a pathologic fracture through the neck of the humerus.
[X-Ray] The AP radiograph of the shoulder at presentation. It demonstrates a trabeculated radiolucent lesion involving the majority of the humeral head with extension into the proximal shaft of the humerus. There is a non-displaced fracture at the junction of the metaphysis and diaphysis.
[Iso-Scan] The regional isotope scan. It shows a solitary lesion with intense increased focal uptake.
[CT Scan] A first generation axial CT image. The CT image shows modest areas of calcification within the lesion, cortical destruction and minimal periosteal response.
[MRI] The coronal T-1 weighted MRI. The MRI has a low-intensity signal on the T-1 images with significant previously unrecognized distal extension into the medullary canal of the proximal humerus and a small extraosseous soft tissue mass.
An incisional biopsy was obtained.
[Micro] A panoramic view of the periphery of the lesion.The panoramic view of the periphery of the lesion shows a moderately cellular tissue. There are many large cells with centralized nuclei. At the bottom of the field loose reactive tissue surrounds the lesion.
[Micro] A field from the interior of the biopsy specimen. This higher power field from the interior of the biopsy specimen demonstrates cells with clear cytoplasm, large, round central nucleii, and faintly eosinophilic matrix between the cells. Double nuclei are abundant.
[Micro] A higher power field from the interior of the biopsy specimen. This field from the interior of the biopsy specimen shows the large chondrocytes that characterize clear cell chondrosarcoma.
Diagnosis: Clear Cell Chondrosarcoma
The moderate cell to matrix ratio, well differentiated tissue, and few mitotic figures are features of a low grade lesion that has extended into the soft tissues as a Stage I-B lesion.
Stage: I-B
As neither chemotherapy or radiation therapy are useful for this lesion a wide surgical margin is necessary. In this anatomic setting it can be obtained with an intrarticular resection of the proximal third of the humerus
Treatment: Wide resection
Follow-up: A wide resection of the proximal humerus was done.
[Surgical Path] Intra-operative photograph. The bed of the resection.
The defect was reconstructed with an osteoarticular allograft.
[Surgical Path] Intra-operative photograph. The allograft is in place and secured with a plate and screws.
[Gross Path] Coronal surfaces of the sectioned surgical specimen. The region of the pathologic fracture and extraosseous tumor extension can be seen. Within the humeral head, the lesion has a hemorrhagic appearance.
[Follow-up] Post-operative radiograph of the reconstruction.
An 8 year-old boy presented with a six week history of mid thoracic back pain and was noted by his mother to have a "crooked back".
[X-Ray] AP radiograph of his thoracic spine at presentation. It demonstrates a mild thoracic scoliosis convex to the right with the apex at T6.
[Iso-Scan] A bone scan was obtained. It demonstrates increased activity in the thoracic vertebrae at the apex of the curve.
[CT Scan] A CT scan of the spine was then performed. This axial image is cut through the 6th thoracic vertebrate. It reveals a lesion involving the right pedicle that has extended within the spinal canal. There is increased mineralization within the pedicular lesion.
[CT Scan] The close up view of the previous CT image shows a well-demarcated lesion occupying the pedicle and extending into the vertebral body. There is a rim of radiodense bone at the lesion's edge as well as a central area of radiodensity.
An open biopsy of the lesion was then taken.
[Micro] A panoramic field from the edge of the lesion. The lower half of the field contains the peripheral edge of the lesion that is bounded by a thin capsule of mature fibrous tissue. The lesion contains numerous thin non-stress oriented trabeculae of bone separated by cellular basophilic tissue.
[Micro] A high power field from the interior of the biopsy specimen This magnification shows the trabeculae in finer detail, heavily lined with plump osteoblasts. The trabeculae vary in their degree of mineralization and the intervening stroma contains numerous small multinucleated giant cells.
[Micro] An adjacent field from the interior of the specimen. It again shows faintly eosinophilic plump trabeculae with prominent osteoblastic rimming as well as numerous multinucleated giant cells. . [Micro] A higher power field from the biopsy. Greater magnification shows a multinucleated giant cell as well s numerous hyperchromatic osteoblasts. There is , however, no cellular atypia suggesting malignancy.
Diagnosis: Osteoblastoma
Stage: 2
Osteoblastoma is a benign osteoblastic neoplasm which resembles osteoid osteoma but is typically larger and has a greater potential for aggressive growth. It typically occurs below the age of 30 with peak incidence in the second decade of life. Males are affected twice as often as females and there is a predilection for the axial skeleton. The spine is involved in about 50 percent of cases and it usually arises in the posterior elements. It typically causes dull pain and may be associated with scoliosis or nerve compression.
Differention from osteoid osteoma may be difficult. Generally, osteoblastomas are larger, measuring from 2 to 6 cm and tend to be less radiodense. They tend to lack the dense reactive bone that surrounds the nidus seen in osteoid osteoma. In tubular bones osteoblastoma is commonly intramedullary rather than cortically situated. The associated pain is less severe than O.O. but may also be relieved by aspirin. Histologically osteobalstoma lacks the peripheral fibrovascular rim and the zonal maturation of trabeculae seen in in the central nidus of osteoid osteoma.
Treatment: Curettage
Treatment is by complete curettage or resection when practical. In this situation where neurological impairment is imminent conservative curettage coupled with low dose radiation is prudent. Some success with refractory lesions has been reported with adriamycin.
A 5-year-old male presented with a symptomatic lesion in the proximal tibia. On exam he had diffuse tenderness over the anterolateral proximal tibia and a slight limp.
[X-Ray] Lateral radiograph at presentation. The underexposed radiograph shows a faintly radiolucent oval lesion centered in the tibial metaphysis.
[X-Ray] AP radiograph at presentation. This with its' crisp geographic, eccentric, metaphyseal location is suggestive of either a non-ossifying fibroma or a chondroid myxofibroma.
[CT Scan] Axial CT cut through the mid-portion of the lesion. It clearly demonstrates the eccentric location and a heavy rim of reactive bone that produces an abrupt transition between the lesion and the intramedullary canal.
The clinical and radiographic findings support an aggressive, benign process. The differential possibilities include chondromyxofibroma, infection, fibrous dysplasia and, less likely, non-ossifying fibroma, simple cyst, or aneurysmal bone cyst.
An incisional biopsy was performed. The incisional biopsy revealed soft, friable, tan-gray material which, histologically, consisted of primitive chondroid matrix, myxomatous regions and surrounding areas of fibroblastic cells with wavy collagenous stroma. These histologic components are characteristic of chondromyxofibroma.
[Micro] A panoramic field from the edge of the lesion. It shows two distinct components - more cellular basophilic areas interspersed in a less cellular very faintly stained almost trnslucent tissue.
[Micro] A field from the edge of the lesion. The faintly staining matrix is chondroid which predominates in this field. The lesion has surrounded (and is destroying) a trabecula of lamellar bone.
[Micro] A field from the interior of the lesion. The stellate configuration of the chondrocytes give the tissue a distinctive myxoid cast.
[Micro] Greater magnification of the previous field. This is shown well in this field.
[Micro] A field from the more basophilic areas of the tissue. This field is composed of spindle shaped cells separated by eosinophilic strands of collagen.
[Micro] Greater magnification of he previous field. Here the fibrous nature of the spindle cell component is easily appreciatted.
[Micro] A field containing both tissue types. This field shows the contrast between the chondroid (right) and fibrous (left) components of the tissue.
Diagnosis: Chondromyxofibroma
Stage: 2
Treatment: Curettage
Treatment for stage 2 chondromyxofibroma is curettage. Bone grafting is dependent on the size of the lesion and agfe of the patient. In this case the large cavity produced by the thorough curettage was filled with freeze-dried, allogeneic bone graft.
[Follow-up] Postoperative radiograph.
A 32 year old woman who noted decreased flexion in her right knee with posterior fullness about 3 years ago. She had associated mild knee pain. She denied any systemic symptoms including fever, chills, change in appetite or weight, nausea, vomiting and diarrhea. Her past history was noncontributory. The physical exam demonstrated popliteal fullness and decreased knee flexion from 0 - 50 degrees.
[X-Ray] - The AP x-ray of the knee demonstrates an osteoblastic mass involving the distal femur.
[X-Ray] - The lateral x-ray of the knee demonstrates a large posterior heavily mineralized lesion about the distal femur extending from the posterior cortex of the femur into the popliteal fossa without evidence of cortical destruction or intramedullary extension.
[CT] - The axial CT scan of the distal femur demonstrates a posterior osseous lesion with areas of radiolucency. The posterior cortex is intact, there is extension into the intercondylar notch but there is no periosteal reaction. These findings in addition to the x-rays are highly suggestive of a parosteal osteosarcoma.
[CT] - Another representative image from the axial CT of the distal femur See discussion to Figure #3.
[MRI] - The sagittal MRI of the distal femur and knee demonstrates a large heterogenous posterior lesion closely approximated to the posterior cortex. There is no intramedullary involvement. The extension of the mass into the soft tissues has displaced the neurovascular structures. The minimal reactive zone is indicative of a low grade lesion.
[MRI] - The axial MRI shows the posterior lesion closely approximated to the posterior cortex of the femur. There are well defined geographic borders in the soft tissue with displacement of the popliteal vessels. The increased signals inside the mass are nonspecific and may represent an area of necrosis, neovascularization, or a focus of de-differentiated osteosarcoma.
[CT] - The CT scan of the lungs shows no signs of metastatic lesions.
An incisional biopsy was done from a posterolateral approach
[Micro] - The low power field from the biopsy is consistent with a classic low grade parosteal osteosarcoma. The most prominent features include a repetitive pattern of heavy trabeculae containing "Pagetoid" cement lines and a monotonous stroma of mature, spindle cells without cytologic atypia.
[Micro] - The higher power field shows that the stromal cells are rather bland, with no obvious atypia. Importantly, no osteoblastic rimming is visible about the trabeculae.
[Micro] - A high power field from the same field. See discussion to Figure #9.
[Micro] - The panoramic field from another area of the biopsy contains more cellular basophilic tissue in the right lower quadrant.
[Micro] - The high power field from Figure 11 consists of highly cellular tissue with prominent cellular atypia and pleomorphism. In addition, mitotic figures are visible highlighting its aggressive qualities. This represents a high-grade de-differentiated focus within the parosteal osteosarcoma.
[Micro] - The contrast between the low-grade and high-grade osteosarcoma is shown in this field containing the low grade tissue in the upper portion of the field and the high grade tissue abutting it in the lower portion.
[Gross] - A resection of the distal femur with a focally marginal margin along the dissection of the popliteal vessels was done. This sagittal section shows the intimate relationship between the "parosteal" mass and the posterior cortex of the femur without extension into the femur.
[X-Ray] - This is a postoperative x-ray. The defect was reconstructed with a rotating-hinge megaprosthesis. The patient is receiving postoperative chemotherapy for her Stage IIB de-differentiated parosteal osteosarcoma.
Diagnosis: parosteal osteosarcoma
This is a classic example of a parosteal osteosarcoma. However, the histopathology demonstrates a focus of de-differentiation. Therefore, this is a high grade osteosarcoma.
Stage: Stage IIB
The most appropriate answer is a Stage IIB lesion because of the de-differentiated component. However, based on imaging alone one may suspect a low grade parosteal osteosarcoma making this a Stage IB (partial credit).
Treatment: Palliative radiotherapy
A 23 year old male presented with insidious onset of mild left thigh pain.
[X-Ray] A AP radiograph of the lesion. This is an AP of the distal femur and knee in a skeletally mature individual. On the medial portion of the metadiaphysial area is a radiolucent lesion with a rim of reactive bone, very thin medially and more substantial proximally and laterally.
[X-Ray] A lateral radiograph of the lesion. Once again a radiolucent lesion is noted with some reactive thickening posteriorly but without the same type of extension seen on the AP.
[CT] A proximal axial CT cut through the lesion. A thick reactive rim of bone is seen with fine stippled mineralization in the center of the lesion.
[CT] An axial CT cut through the mid-portion of the lesion. The lesion is larger more distally with a thinner rim of bone. Again, there is some stippled mineralization present.
[CT] Another axial CT cut through the mid-portion of the lesion . The rim of reactive bone is very thin with the lesion making up a larger component. There is only a hint of matrix mineralization on this cut.
[CT]A distal axial CT cut through the lesion. The lesion is smaller as it approaches the metaphysis of the femur.
[CT] A coronal CT scan through the lesion. A radiolucent lesion with mature, reactive bone and stippled mineralization.
[Micro] A panoramic field from the biopsy specimen. This panoramic field shows the grayish-blue matrix of hyaline-like cartilage. The pink rim represents a narrow band of enchondral ossification encasing the lesion.
[Micro] A higher power field from the field. A field of benign cartilage cells in a basophilic matrix.
Diagnosis: Periosteal chondroma.
Although classically located on the lateral aspect of the proximal humerus, this is a classical appearance of this lesion, a radiolucent lesion on a thickened crater of cortical bone. The CT scan nicely shows the punctuate areas of calcification, hinting at the cartilaginous matrix. A differential could include juxtacortical chondrosarcoma or even periosteal osteosarcoma, but there is no soft tissue mass, no medullary involvement, and no permeation one would see with malignant lesions.
MSTS Stage: Stage: 2
This is slow growing lesion evidenced by the reactive rim of mature bone. Although it has enlarged the diameter of the bone, it is still contained by the rim of reactive bone.
Treatment: Wide excision
Either a wide margin or marginal margin plus an effective physical adjuvant (cement, cryosurgery, or argon laser) will yield a recurrence rate less than 10%. Curettage alone will give an unacceptable recurrence rate of 30%. This patient received a marginal resection with adjuvant argon laser.
Radiation: N/A
Chemotherapy: N/A
[Follow-Up] A follow-up radiograph.
A 6-year-old boy presented with a tender mass about the lateral aspect of the knee.
[X-Ray] AP radiograph of the upper leg at presentation.
[X-Ray] Lateral radiograph of the upper leg at presentation.
[X-Ray] Magnification of the AP radiograph of the proximal fibula. There is a destructive, permeative process involving the proximal fibula. Although the soft tissue extension appears to be bounded by a thin shell of reactive bone, there are several areas of discontinuity. These features are compatible with a marrow-cell lesion, a metastatic lesion, an infection, or an aggressive benign process.
[Iso-Scan] A regional isotope scan of the knees. The intense focal isotope uptake does not appear to extend appreciably beyond the radiographic extent of the lesion.
[CT Scan] Axial CT (soft tissue window) cut through the proximal fibular metaphysis.
[CT Scan] Axial CT (bone window) cut through the proximal fibular metaphysis. Soft-tissue and bone window axial CT through the mid-portion of the lesion shows the lesion with a soft-tissue density matrix, expansile remodelling of the proximal fibula and no obvious soft-tissue extension. These features are more suggestive of a neoplasm than an infection.
Incisional biopsy was performed.
[Micro] A representative panoramic field from the biopsy specimen. The field is composed of a monotonous mass of cells that has displaced the normal marrow contents between the trabeculae. The trabeculae themselves appear intact although at this magnification it is difficult to ascertain whether the bone is viable or necrotic.
[Micro] Low magnification field from the previous field. At this magnification the tissue appears composed of clusters of small round basophilic cels that are producing little or no matrix. In some areas there is a modest amount of eosinophilic amorphus material between the cells. Althuogh there is not the usual amount of mesenchymal cells and capillaries associated with an infection, it is not possible to distinguish whether the round cells are inflammatory or neoplastic.
[Micro] Medium power magnification from the previous field. At greater magnification the heavily basophilic round cells are clearly not inflammatory nor are there and other components of chronic inflammatory tissue. In several areas, but particularly just to the left of center, the lesional cels are arranged in a circle about a central amount of eosinophilic material in a fashion highly suggestive of a rosette seen in neuroblastoma or a pseudorosette seen in Ewing's sarcoma. Clearly the lesional cells are not the plasma cells of a myeloma or the lymphocytes of leukemia.
[Micro] High power magnification from the previous field. In this field almost all the cells are arranged in the rosette-like pattern.
[Micro] A PAS stain of a field from the biopsy specimen. The PAS (Periodic Acid Schiff) stain stains the glycogen in the cytoplasm of the neolastic cells in Ewing's sarcoma. Although it may be positive in other glcogen bearing tissues, it is useful in separating Ewing's sarcoma from other similar round cell neoplasms. Usually over 70% of the cells in Ewing's will be PAS positive.
[Micro] An eletron micrograph from the previous field. Electron microscopy is another technique of identifying glycogen in the cytoplasm of neoplastic cells. It appears in small round vacuoles as bubbles of clear material. In the smallest cell immediately adjacent to the central point in the field at the one o'clock position where the cytoplasm points as a finger towards the upper right corner, several of these vacuoles are evident. This feature again is by itself not pathognomonic of Ewing's sarcoma, but taken with the other findings is highly confirmatory.
Diagnosis: Ewing's sarcoma
MSTS Stage: NA Ewing's sarcoma, as with other round cell marrow derived neoplasms (leukemia, lymphoma, myeloma, etc.) have a different natural history than the mesenchymal derived sarcomas and are staged by different systems.
Treatment: Preoperative chemotherapy/Wide excision.
The patient recieved four cycles of preoperative chemotherapy followed by en bloc resection of the proximal 40% of the fibula.
[Gross Path] The biseccted surgical specimen. The lesion was composed of soft, vascular, granulomatous-like tissue.
[Macro] A coronal macrosection of the surgical specimen. The pervasive cellular lesion extended well beyond the radiographic limits of the lesion and quite close to the plane of dissection so that the resection obtained a focally marginal margin. In view of this the patient recieved post-operative radiation therapy.
[Follow-up] Post-operative radiograph. The radiograph shows the extent of the resection and the planned radiation field.
The patient remained continuously disease free at last follow up eleven years later.