INTRODUCTION
Giant Cell Tumor of Bone (GCTB) is uncommon benign lesion, but locally aggressive that most frequently affecting the epiphysis of long bones especially around the knee [1]. The epiphyseal region is the common site for GCTB development, however, other frequent regions may occur as the distal femur, proximal tibia, distal radius and sacrum, rarely reported in the bones of the head, some reports of bones developing from endochondral ossification, such as sphenoid, ethmoid and temporal bone, are almost exclusively involved [3]. In the gnathic bones, the clinical appearance may vary, causing since dental root resorption to bone destruction, pain, pathologic fractures and metastatic spread [4]
It has a clinically aggressive behavior, with a fast growth, sometimes in weeks, however has few symptoms, leading to thinning and rupture of bone cortical, invasion of adjacent soft tissues, but not invading or ulcerating skin and subcutaneous tissue [5]. Albeit the GCTB belongs to the category of benign tumors, some studies prefer to characterize it as having “intermediate malignant potential” due to osteolytic properties causing invasion and destruction of adjacent structures [5].
The treatment for GCTB also may vary, depending on the aggressiveness of the tumor. Surgical resection, Embolisation, Bisphosphonates, Anti-RANKL therapy, Chemotherapy and Radiotherapy can be used4. Nowadays, the use of Denosumab has gained prominence as an adjuvant therapy by the inhibitory effects on RANKL, promoting significant reduction in tumor size, restoration of bone stock, and significant pain reduction in treated patients [6]
A comprehensive study of differential diagnosis should include tumors with similar histological appearance as well as benign or malign epithelial neoplasms with common chronic inflammatory conditions in the gnathic bones, nasal cavity and paranasal sinuses, such as brown tumor of hyperparathyroidism, malignant fibrous histiocytoma, giant cell central granuloma and chronic inflammatory masses from nasal cavity [7,8]
In this context, we aimed to present a singular rare clinical case of GCTB in the right maxillary sinus extending to the nasal cavity and skull base, implicated in a process coincidentally or casually with another type of lesion primarily developed.