This digital library houses the book on Oncology and Orthopedic Oncosurgery.

It includes academic lectures, presentations from national and international congresses, published papers, case discussions, performed surgical procedures, and proprietary techniques developed.

The digital format was chosen because the web allows the inclusion of texts with numerous visual resources, such as images and videos, which would not be possible in a printed book.

The content is intended for students, healthcare professionals, and the general public interested in the field.

Pseudotumor Bone Lesions

Lesões Ósseas Pseudotumorais

Pseudotumor Bone Lesions

The group of diseases known as pseudotumor bone lesions corresponds to the set of bone changes that mimic, from a radiographic point of view, tumor lesions.

Pseudotumor Bone Lesions

The injuries that are part of this group are:

  1. Simple bone cyst
  2. Aneurysmal bone cyst
  3. Juxtacortical bone cyst (Intraosseous ganglion)
  4. Metaphyseal fibrous defect  ( non-ossifying fibroma )
  5. Eosinophilic granuloma
  6. Fibrous dysplasia  /  osteofibrodysplasia
  7. Myositis ossificans
  8. Brown tumor of hyperparathyroidism
  9. Intraosseous epidermoid cyst
  10. Giant cell reparative granuloma
Lesões Ósseas Pseudotumorais
What is this child's diagnosis?
  • Simple Bone Cyst

The  Simple Bone Cyst  is a cavity, initially unicameral, filled with clear liquid surrounded by a membrane, with vascularized connective tissue showing osteoclastic giant cells, and there may be some areas of hemorrhage or fissures with content rich in cholesterol.

Diagrama do C.O.S.
COS Diagram
  • It occurs between 5 and 15 years of age, with a slight predominance in males. It most frequently affects the proximal metaphyseal region of the humerus and femur.

    Although its etiology is still unknown, we have seen contrast inside vessels when we infiltrate the cavity, which makes us assume that it is a vascular phenomenon.

    The fracture is often the first manifestation of the cyst, which has often evolved asymptomatically.

    It appears as a radio-transparent lesion in the metaphyseal region of long bones, centrally located, not exceeding the width of the epiphyseal line. With growth, the simple bone cyst moves away from the growth plate, occupying a meta-diaphyseal position, and can erode and fracture the cortex.

                Its treatment is generally non-operative, classically performed with a series of three corticosteroid injections, at intervals of four weeks. In load-bearing bones, particularly in the femoral neck region, we must consider the possibility of surgical treatment, with curettage and bone grafting.


      Unicameral cavity filled with clear or bloody fluid and limited by a membrane of variable thickness, with vascularized connective tissue showing osteoclastic giant cells and some areas with recent or old hemorrhage or fissures with cholesterol-rich content (OMS)


    In the treatment of musculoskeletal tumors, we observed a predominance of cases in the age group between 5 and 15 years, with a slight predominance of cases in males, and the majority involving the proximal metaphyseal region of the humerus and femur. The vast majority are referred due to an episode of fracture caused by trauma at the site of the injury or as an x-ray finding during an eventual x-ray taken due to some trauma suffered by the patient.


    Although its recognition from a radiographic point of view is simple, its etiology is still unknown.

    Clinical Assessment:

    Most patients present asymptomatically, and fractures are often the reason for their first consultation with an orthopedist. Some patients report sporadic episodes of pain or functional limitation before the presence of a bone cyst is diagnosed.

    Radiographic Characteristics:

    The Simple Bone Cyst presents as a radiolucent lesion in the metaphyseal region of long bones, centrally located, mainly in the proximal region of the humerus and femur and close to the epiphyseal line. They are well-defined lesions, with sclerotic edges, rarely crossing the limits of the cortex or the limits of the bone, expanding, thinning the cortex, but almost never breaking it. In some cases, the “fallen fragment” sign can be observed, which represents fragments of the cortical wall loose within the cyst.


    COS treatment depends on its location and size, in the vast majority of cases it can be conservative and non-operative. In general, treatment for the upper limb is less surgical and more conservative, whereas treatment for the lower limb tends to be more surgical, in an attempt to avoid a fracture. The classic treatment consists of infiltrations with corticosteroids (depomedrol), observing whether or not bone content is formed inside. If there is an imminent fracture in a load-bearing bone, we should seriously consider the possibility of intra-lesional treatment filling the cavity with either an autologous or homologous graft.

    1-  Click to see more :ósseo_simples

    2-  Reconstruction of the femoral neck with fracture due to bone cyst

    • Aneurysmal Bone Cyst


    Expansive, blood-filled osteolytic lesion between variable-sized spaces separated by connective tissue septa containing trabeculae of bone or osteoid tissue and osteoclastic giant cells.


    Aneurysmal Bone Cysts are more frequent in the first three decades of life, with their peak incidence occurring around 10 to 15 years of age, with a slight predominance in females than in males.


    The origin and etiology are still unknown

    Clinical Assessment:

    Patients normally present with mild pain at the site of the injury and inflammatory signs such as increased volume and heat at the site are often observed. When there is a compromise in the spine, there may be neurological symptoms of spinal cord or nerve root compression. The evolution is very variable with a slow and progressive increase in volume or in some cases rapidly expansive. It frequently affects the lower limbs and vertebrae, including the sacrum and the pelvis, mainly in the iliopubic branch.

    Radiographic Characteristics:

    It presents an insufflative and radiotransparent lesion mainly in the metaphyseal or diaphyseal region of long bones, with the presence of septa scattered throughout its content, with thinning and expansion of the cortex, which may be eccentric or central.

Diagrama do cisto ósseo aneurismático
Aneurysmal bone cyst diagram


The treatment of choice has been intralesional curettage and filling with autologous graft. Oftentimes, it may or may not be possible to associate intra-lesional adjuvant treatment with the application of phenol, or electro cauterization or the use of cryotherapy. Rarely and in some specific cases, it is possible to resect the compromised bone without compromising function, as in cases of involvement of the rib, fibula and metacarpal and metatarsal bones. Recurrence is very rare.

Cisto aneurismático da fíbula; lesão sendo ressecada e leito operatório após a retirada da lesão.
Aneurysmal cyst of the fibula; lesion being resected and operating bed after removal of the lesion.
Peça ressecada; radiografia pós operatória e paciente com carga monopodal, boa função sem instabilidade.
Dry piece; Post-operative x-ray and patient with single-leg weight bearing, good function without instability.

1-  Click here to see more :ático

  • Eosinophilic granuloma

(Histiocytosis X, Langerhans Cell Granuloma, Reticuloendotheliosis)

Eosinophilic Granuloma is   a pseudo-tumor lesion, also of unknown etiology, characterized by intense proliferation of reticulohistiocytic elements with a variable number of eosinophils, neutrophils, lymphocytes, plasma cells and multinucleated giant cells. It presents frequent areas of necrosis, as well as the presence of numerous fatty cells.

Among reticuloendotheliosis, eosinophilic granuloma presents as a single lesion, preferentially affecting the diaphyseal and metaphyseal regions of long bones. These single lesions may resolve spontaneously over time, ranging from months to years. They are rarely disabling or cause pathological fractures.

Reticuloendotheliosis in the multiple form characterizes Hand-Schuller-Christian disease, which presents multiple lesions in the skullcap and frequently affects other tissues, with Diabetes insipidus (due to involvement of the parapituitary gland), exophthalmos and lesions in the liver and spleen occurring.

In the most severe form, Letterer-Siwe, the frequent clinical findings are fever, otitis media, frequent history of bacterial infections and, in some cases, we observe anemia, hepatosplenomegaly, hemorrhage with no apparent cause, lymphadenopathy and disseminated bone lesions. Evolution is often fatal due to severe systemic involvement.

The radiographic appearance of eosinophilic granuloma itself is a radiolucent lesion, with a rounded or ovoid shape, with delimited and well-defined edges, in the diaphyseal region of long bones and, sometimes, in the metaphyseal region, causing cortical erosion and a periosteal reaction. onion skin”, mimicking the periosteal reaction of Ewing Sarcoma, but in eosinophilic granuloma it is of the thick lamellar type.

When it affects the spine, it causes collapse of the  “Calvé vertebrae” vertebra , but rarely leads to neurological impairment.

Vértebra plana de Calvé – Granuloma eosinófilo do úmero – Aspecto clínico do braço
Flat vertebra of Calvé – Eosinophilic granuloma of the humerus – Clinical appearance of the arm
Aspecto intra-operatório, com erosões na cortical – material de curetagem
Intra-operative appearance, with cortical erosions – curettage material

In single lesions, treatment is curettage and bone grafting when necessary. 

Definition:  Non-neoplastic lesion of unknown etiology, characterized by an intense proliferation of reticulohistiocytic elements with a variable number of eosinophils, neutrophils, lymphocytes, plasma cells and multinucleated giant cells. Frequent areas of necrosis, as well as the presence of fat cells, especially in old and multiple lesions.

Incidence:  Reticuloendotheliosis presents several forms of involvement, but is mainly divided into three basic forms: Eosinophilic Granuloma (75%), Hand-Schuller-Christian (15%) and Letterer-Siwe (10%).

Eosinophilic granuloma: 5 to 20 years

Hand-Schuller-Christian: 3 to 5 years

Letterer-Siwe: 1 to 3 years

Etiology:  Reticuloendotheliosis does not have a known etiology, however some authors relate it to a probable viral or immunological cause, due to the presence of an inflammatory phenomenon with the formation of a hyperplastic granulomatous process, often similar to neoplastic processes.

Clinical Manifestations:  The natural history of the evolution of this disease will depend on one of the three forms in which it presents itself.

– Eosinophilic granuloma: most of the time it presents as a single lesion, preferentially affecting the diaphyseal and metaphyseal region of the long bones, and more rarely we also see cases with multiple involvement, which can be simultaneous or consecutive, starting in adolescence and dragging itself into young adulthood. Single injuries often end up resolving spontaneously over time, ranging from months to years, and are rarely disabling or lead to a pathological fracture.

– Hand-Schuller-Christian: normally presents with multiple lesions, which are more difficult to treat and evolve in a more disabling way than Eosinophilic Granuloma. They frequently present secondary involvement of other tissues, frequently progressing to Diabetes insipidus (involvement of the parapituitary gland), exophthalmos due to orbital involvement and involvement of the liver and spleen.

– Letterer-Siwe: the most frequent clinical findings are fever, otitis media and a frequent history of bacterial infections, and in some cases there is anemia, hepatosplenomegaly, bleeding with no apparent cause, lymphadenopathy and disseminated bone lesions. Evolution is often fatal due to systemic involvement.

Radiographic Aspects:  The lesions have a radio-transparent appearance, with a rounded and ovoid shape, with well-defined and well-defined edges, and trabeculae within them can often be visible. They frequently affect the diaphyseal region of long bones and less commonly in the metaphyseal region, causing cortical erosion and slight cortical expansion. It is possible to visualize a small periosteal lift with an “onion skin” reaction similar to that of Ewing Sarcoma and osteomyelitis.

When the involvement is in the spine, it rarely leads to neurological impairment, although there is a collapse of the vertebra, presenting a flattening and known as “Calvé’s flat vertebra”.

In more serious cases, such as Hand-Schüller-Christian Syndrome and Letterer-Siwe Syndrome, disseminated radio-transparent lesions are observed in the cranial vault.

Treatment and Prognosis : The treatment and prognosis of the disease depend directly on the degree of involvement and clinical manifestations. In single lesions, the treatment of choice is curettage and in large defects, filling with cancellous bone. In some cases where there is no impairment of function or aesthetic impairment, resection of the compromised bone can be performed, such as the ribs, clavicle, and upper part of the fibula. In cases of multiple and systemic involvement, part of the treatment is carried out with the use of chemotherapy drugs and corticosteroid therapy. 

1-  Click to see more:ófilo-por

2-  Case of polyostotic eosinophilic granuloma :ófilo_do-Rádio


  • Cortical fibrous defect / Non-ossifying fibroma

                      The cortical fibrous defect is a benign non-neoplastic bone lesion, of unknown cause, which is characterized by fibrous proliferation in a small area of ​​cortical bone. Non-ossifying fibroma is the same process, with a larger size.

                        The cortical fibrous defect generally does not present any clinical symptoms or signs. In the vast majority of cases it is diagnosed in an x-ray examination carried out for some reason. When it takes on the characteristics of a non-ossifying fibroma, it may manifest as mild pain, a protrusion noticeable by the patient or, less frequently, a fracture. 

Fibroma não ossificante, acompanhado clinicamente, sem intervenção.
Non-ossifying fibroma, clinically monitored, without intervention.

 They are usually found in the metaphysis of long bones, mainly in the distal femur and proximal tibia.

                      On radiographs, the cortical fibrous defect appears as a small radio-transparent lesion, measuring approximately 1 to 2 cm, eccentric, as it is located in the cortex of the metaphysis of long bones. At first they are rounded and over time they become oval, with the largest diameter along the longitudinal axis in relation to the involved bone. The process is superficial and restricted to the cortex, easily determined by computed tomography.


  • Fibrous Dysplasia and Osteofibrodysplasia

                  Fibrous dysplasia is a pseudotumor lesion, characterized by failure in the development of one or more bones, which remain with partial replacement of the bone by fibrous tissue amid irregularly arranged osteoid beams. Radiographically, the lesion is radio transparent, with the appearance of “ground” glass.

                 It can manifest itself in two clinical forms: solitary (monostotic) and multiple (polyostotic), and skin pigmentation may occur.

Displasia fibrosa no colo femoral – Mancha café com leite e puberdade precoce (Albright)
Fibrous dysplasia in the femoral neck – Café au lait spot and precocious puberty (Albright)
Evolução com deformidade e arqueamento do fêmur – Paciente adolescente com encurtamento pela deformidade angular.
Evolution with deformity and bowing of the femur – Adolescent patient with shortening due to angular deformity.

Albright described the syndrome with “fibrous osteitis” in multiple bones, accompanied by skin patches and precocious puberty in females. Endocrine disorders such as hyperthyroidism, diabetes, Cushing’s syndrome, in addition to hypertension and mental retardation, may be associated. The association of polyostotic fibrous dysplasia and soft tissue myxomas is known as Mazabraud syndrome.

                  Monostotic fibrous dysplasia most of the time presents no symptoms. It is a congenital bone modeling defect, most frequently manifesting itself in the first and second decade of life. Deformity, fracture or casual finding on x-rays are the main occurrences that lead the patient to an appointment. 

                 Treatment, when necessary, must be surgical, as there is no clinical treatment for any of the forms of fibrous dysplasia. The lesion or lesions generally stop progressing with growth and usually cease with puberty. Surgical intervention will be indicated for orthopedic corrections when there are deformities or risks of imminent fracture. 

                    The malignancy of fibrous dysplasia is rare, and cases of transformation to osteosarcoma and chondrosarcoma may occur.

                    Single lesions of fibrous dysplasia may resemble desmoplastic fibroma, central chondrosarcoma, or adamantinoma of long bones. When the patient presents with cysts, the differential diagnosis with adamantinoma of long bones may be difficult on radiographic examination.

                    Histologically, the main differential diagnoses are desmoplastic fibroma, adamantinoma of long bones and osteofibrodysplasia.

Lesão cortical pequena; aumento da lesão, evolução agressiva e deformidade; aspecto clínico da deformidade.
Small cortical lesion; increase in injury, aggressive evolution and deformity; clinical aspect of the deformity.
Acesso cirúrgico amplo, com margem; ressecção da lesão; tibialização da fíbula para a reconstrução.
Wide surgical access, with margin; resection of the lesion; tibialization of the fibula for reconstruction.
Pós operatório imediato; consolidação e espessamento da fíbula rx frente; Rx perfil; fíbula completamente tibializada.
Immediate post-operative period; consolidation and thickening of the fibula front rx; Rx profile; completely tibialized fibula.
When osteofibrodysplasia manifests itself in the first years of life, it is necessary to intervene early to stop the progression of the lesion and prevent deformities.
Osteofibrodisplasia com um ano – Planejamento cirúrgico com 3 anos
Osteofibrodysplasia at one year – Surgical planning at 3 years
Cirurgia= tibialização da fíbula – Integração do enxerto e função.
Surgery = tibialization of the fibula – Integration of the graft and function.

See the complete technique.

                    In osteofibrodysplasia, the histological appearance is very similar to that of fibrous dysplasia. Only intracortical location in the tibia or fibula will enable the differential diagnosis.


  • Brown Tumor of Hyperparathyroidism


          It is a metabolic disease that, when not diagnosed early, can lead to a process that simulates a tumoral appearance, with numerous lesions due to foci of bone resorption due to primary hyperparathyroidism. It is a non-neoplastic lesion that presents numerous multinucleated giant cells.

          It is caused by a parathyroid adenoma and has a slow and insidious onset, predominating in female adults, presenting diverse clinical manifestations such as nausea, indigestion, loss of appetite, recurrent renal calculosis and fractures with no apparent cause or due to mild trauma and , eventually, psychic changes.

           Hypercalcemia accompanied by hypercalciuria, hypophosphatemia, hyperphosphaturia and increased parathyroid hormone in the blood close the laboratory diagnosis. When left untreated, increasingly intense bone changes can occur, up to generalized fibrocystic osteitis or Von Recklinghausen’s disease of the bones.

           The initial lesions of hyperparathyroidism occur as foci of subperiosteal bone resorption in the phalanges of the hands and resorption of the “lamina dura” of tooth implantation in the alveoli.

Múltiplas lesões no esqueleto, paciente há 6 anos sem diagnóstico (“metástase de câncer à esclarecer)
Multiple skeletal lesions, patient undiagnosed for 6 years (“cancer metastasis to be clarified)
Reabsorção sub-periosteal das falanges; fratura do fêmur, adenoma da paratireoide (seta preta) .
Sub-periosteal reabsorption of the phalanges; femur fracture, parathyroid adenoma (black arrow).
Osteossíntese e consolidação da fratura, carga total após 3 meses; paciente diagnosticada corretamente e restabelecida.
Osteosynthesis and fracture consolidation, full weight-bearing after 3 months; patient correctly diagnosed and restored.
 Treatment consists of excision of the parathyroid adenoma, taking care to replace calcium, as the skeleton is avid and cramps may occur due to hypocalcemia. After parathyroid surgery, fractures heal quickly and bone injuries regress quickly.

Author: Prof. Dr. Pedro Péricles Ribeiro Baptista

 Orthopedic Oncosurgery at the Dr. Arnaldo Vieira de Carvalho Cancer Institute

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