2. Parameters:

We must analyze the following aspects of the injury:

1) Identify the compromised bone or bones;

2) Regarding the number of injuries:  

          2.1) Located in a bone: monotopic;

          2.2) A lesion in several bones: monotopic and polyostotic;

          2.3) Multiple lesions in one bone: polytopic and monostotic;

          2.4) Multiple lesions in different bones: polytopic and polyostotic.

3) Regarding location in the bone:

          3.1) Epiphysis, metaphysis or diaphysis;

          3.2) Cortical, spongy, subperiosteal, paraosteal or juxta-cortical region;

          3.3) Central or eccentric.

4) Limits of bone injury:

          4.1) Precise, imprecise, infiltrative or permeative, surrounded or not by reactional sclerosis;

          4.2) It goes beyond the cortex with an extra-osseous lesion;

          4.3) It reaches the soft tissues (yes/no) (displaces/infiltrates);

          4.4) Exceeds the growth line.

5) Regarding other aspects of the injury:

          5.1) Destructive (osteolytic)

          5.2) Condensing or osteogenic

          5.3) Multiloculated, “in soap bubbles”

          5.4) Calcifications: focal, diffuse, striated

6) Type of periosteal reaction:

          6.1) In thin slices – “in onion skins”

          6.2) In thick sheets

          6.3) Spiculates – “in sunbeams” or “in a comb”

          6.4) Periosteal survey interrupted by the tumor – Codman’s Triangle

3. Diagnosis:

 Study methods for pathological anatomical examination:

 Cytology:

It is the study of desquamated cells obtained from secretions, excretions or obtained with needles and making “imprints” (printing tissue fragments on slides). It should rarely be used to diagnose bone neoplasia. Its importance lies mainly in the cytohistological correlation.

Punch-biopsy:

Collection of material with trephines for inclusion in paraffin and microscopic examination. Although the material obtained by this method is small, when it is collected from a significant area of ​​the neoplasia and by an orthopedist with experience in handling these lesions, it makes a definitive diagnosis possible. The location for obtaining this material must be planned by the surgeon, in order to prevent disruption of the tumor’s balance in neighboring tissues, preventing its spread.

Incisional biopsy:

It is the most used method for diagnosing bone tumors. The biopsy site must be planned, not only in terms of the area that will enable a better histological diagnosis but also to predict future resection of the tumor, which should include the skin of the biopsied region. The biopsy should not be performed in inappropriate locations of the tumor, such as areas of necrosis, hemorrhage, Codman’s triangle or in areas that only present peritumoral reactional bone sclerosis.

Frozen biopsy

It is performed during the surgical procedure. This method is not recommended when there is bone tissue. The possibility of a diagnostic error is high in this situation. Diagnostic errors in numerous bone lesions with multinucleated giant cells, in the various tumors of undifferentiated cells, small cells and round cells, the impossibility of a histological differential diagnosis when there is neoformed bone tissue in the fracture callus, osteosarcoma and myositis ossificans, are some examples that contraindicate the method. Frozen examination may be useful in cases of metastatic lesions and even so, the speed of the method will not alter the operative approach.

Microscopic study:

Fragments obtained by puncture or incisional biopsy must be embedded in paraffin and subsequently stained with hematoxylin-eosin. Special methods such as PAS (Periodic Acid Schiff) and silver impregnation to study reticulin are usually used for differential diagnosis, for example, between Ewing Sarcoma, Lymphomas and PNET (Primitive Neuroectodermal Tumor). PAS, demonstrating glycogen and a scarce amount of reticulin, are common for diagnosing Ewing’s sarcoma. In Lymphomas, reticulin is abundant and PAS is negative. Immunohistochemistry techniques with immunoperoxidase are entering the routine of anatomopathological examinations. They are mainly indicated in the search for the diagnosis of the organ of origin of metastatic neoplasms in the bones. The use of markers that allow identifying the origin of the neoplastic cell is increasingly used in daily practice. Examples are PSA, to identify neoplasia originating from the prostate, CK7 for primitive lung neoplasia, CK20 for primitive digestive tract neoplasia and estrogen and progesterone receptors for breast neoplasia.

Surgical parts:

Routinely a surgical specimen must be examined externally and at the cuts. Externally for analysis of surgical margins in order to verify whether the neoplasm was completely extirpated. In the sections, we verified the involvement of the bone, extension and dimensions of the neoplasm and its main macroscopic characters for adequate microscopic study. (Figure 1) 

When the study of a surgical resection is of a patient undergoing preoperative chemotherapy, particularly in osteosarcoma and Ewing’s sarcoma, the study of the specimen must follow a systematized examination, as the purpose is to analyze the response of the neoplasm to therapy. The study stages will be as follows:

A) Slices will be made of the surgical piece along its entire length with a maximum thickness of 0.5 cm,

B) One or more slices must be reproduced on a computer “scanner” or photographed and x-rayed,

C) This reproduction must be gridded from the proximal to the distal end,

D) The fragments from each checkered area must be thoroughly examined under a microscope in order to quantify the necrosis of the neoplasm and the persistence of histologically viable tumor cells,

E) The final report of the study of the entire specimen must be graded according to the response to preoperative chemotherapy according to the Huvos criteria.

Huvos Criteria:

Grade I: Up to 50% tumor necrosis;

Grade II: 50 to 90% tumor necrosis;

Grade III: Above 90% necrosis;

Grade IV: 100% tumor necrosis – Absence of histologically viable neoplastic cells.

With this degree, the oncologist will be able to guide post-operative treatment taking into account the worst statistical prognosis in cases of cranes I and II and better in those of III and IV.