Giant Cell Tumor.

Gigantocellular tumor is a neoplasm of mesenchymal nature, characterized by the proliferation of giant multinucleated cells – gigantocytes – that resemble osteoclasts, amidst a stroma of mononucleated cells.

Due to this histological aspect present in several other processes, the gigantocellular tumor could be confused, often requiring analysis of the clinical and radiographic appearance to confirm its diagnosis.

The giant cell tumor is also known by the acronym TGC, by the names giant cell tumor and osteoclastoma.

The main manifestation is intermittent local pain, accompanied or not by an increase in volume in the affected region and limitation of movement in the neighboring joint. The length of history, on average 6 to 12 months, varies from case to case and depends on the affected bone.

Some patients seek treatment due to pain, others because of the perception of the tumor or a pathological fracture. It is not uncommon to refer to more or less intense trauma as the beginning of the clinical history.

As the tumor is most often epiphyseal, clinical involvement of the neighboring joint is frequent, with progressive functional impotence.

Joint effusion and clinical symptoms simulating meniscal or arthritis processes may occur.

In tumors located in the spine and sacrum, in addition to pain and increased volume, neurological manifestations may occur. The volume is sometimes enormous, predominating over the other symptoms.

The gigantocellular tumor generally affects a single bone. When there are lesions in several bones, the possibility of it being a “brown tumor of hyperparathyroidism” must be checked, whose lesions have similar radiographic aspects, but are multiple and the patient presents alterations in calcium and phosphorus.

GCT is classically known as a tumor of the epiphysis of long bones, most common in the knee region, that is, in the distal epiphysis of the femur and proximal epiphysis of the tibia and, then, in order of frequency, in the proximal region of the humerus and distal region of the radius. . It is rare in the axial skeleton and when it occurs, it predominates in the sacrum.

It occurs in the third and fourth decade, affecting both sexes equally.

Radiographically, it is described as an epiphyseal lesion characterized by bone rarefaction, initially eccentric, initially respecting the cortical limits. As it progresses, cortical rupture and joint involvement may occur (fig. 27).

Histologically, giant cells and the stroma are the most important elements of this tumor. It is characterized by having numerous giant cells that resemble osteoclasts in a stroma of spindle cells.

The main clinical, radiographic and anatomopathological differential diagnoses are aneurysmal bone cyst, teleangectatic osteosarcoma and chondroblastoma.

         The treatment of giant cell tumor is currently well established. Whenever possible, segmental resection of the lesion should be chosen, with an oncological safety margin in both bone and soft tissues. This way the surgeon will provide the greatest opportunity for cure, without risk of recurrence.

         However, in regions where segmental resection is not feasible, cervical spine for example, the most judicious endocavitary curettage possible must be performed and complemented with adjuvant therapy such as the CO ₂ laser , phenol diluted in 4% alcohol, the liquid nitrogen and electrothermia. Methylmethacrylate has a low adjuvant effect and, when used to fill the cavity, it must be preceded by one of the therapies mentioned.

         In the past, curettage had high recurrence rates due to the lack of large openings for effective cleaning and the lack of use of local adjuvants. Today, when endocavitary curettage is indicated, it is recommended that a large bone window be created to allow the surgeon a broad view of the cavity. We also complement this curettage with the use of an electric scalpel (electrothermia).

         This electrothermal technique is very effective because with the curved tip of the scalpel we can reach areas that are more difficult to access. This scalpel, in addition to cauterization, also performs a complement to curettage, as those tumor cells, remaining in the small “cavities” of the bone wall, are destroyed and become detached, allowing for easier removal.

         We complement our curettage, after using electrothermia, with milling the cavity. For this we use the  Lentodril , with a spherical dental milling cutter.

         In the knee region (distal end of the femur and proximal end of the tibia), the site with the highest incidence of TGC, we frequently recommend endocavitary curettage, followed by electrothermia and milling with  Lentodril . This is because segmental resection of this region would imply arthrodesis or replacement with endoprostheses or homologous grafts. Arthrodesis of the knee joint causes the greatest limitation for the patient and should be avoided. Replacements in young patients can result in problems in the near future, and their indication must be judicious.

         Therefore, we first recommend the most conservative therapy: – curettage followed by adjuvant therapy for this region, except in advanced cases, with significant destruction of the bone structure, in which both the function and local control of the disease may be compromised.

         A brief comment remains regarding filling the treated cavity. This can be done with autologous or heterologous bone graft or with methyl methacrylate, each of them has its advantages and disadvantages.

         Methyl methacrylate makes it possible to visualize possible recurrences easily, is easy to use and allows for earlier loading, however it is not a biological solution and fractures may occur in the region.

The bone graft is a biological and definitive solution, however it makes it difficult to visualize possible early recurrence, which can be confused with reabsorption/integration of the graft and still requires six months on average for full load. The homologous graft has a longer integration period, is not always available, but on the other hand it shortens surgical time. The autologous graft has the advantage of biocompatibility and faster integration, but it prolongs surgical time.