Theoretically,  several possible mechanisms of both objective and subjective halitosis may be involved.A 2005 review suggested that most "sinus headaches" are migraines. The confusion occurs in part because migraine involves activation of the trigeminal nerves, which innervate both the sinus region and the meninges surrounding the brain. As a result, accurately determining the site from which the pain originates is difficult. People with migraines do not typically have the thick nasal discharge that is a common symptom of a sinus infection.Symptoms of chronic sinusitis may include nasal congestion, facial pain, headache, night-time coughing, an increase in previously minor or controlled asthma symptoms, general malaise, thick green or yellow discharge, feeling of facial fullness or tightness that may worsen when bending over, dizziness, aching teeth, and bad breath. Often, chronic sinusitis can lead to anosmia, the loss of the sense of smell. By location
The four paired paranasal sinuses are the frontal, ethmoidal, maxillary, and sphenoidal sinuses. The ethmoidal sinuses are further subdivided into anterior and posterior ethmoid sinuses, the division of which is defined as the basal lamella of the middle nasal concha.
Tenosynovial giant cell tumor (TGCT) is a group of rare, typically non-malignant tumors of the joints. TGCT tumors often develop from the lining of joints (also known as synovial tissue). : 100 : 245 Common symptoms of TGCT include swelling, pain, stiffness and reduced mobility in the affected joint or limb. : 102  This group of tumors can be divided into different subsets according to their site, growth pattern, and prognosis. : 361  Localized TGCT is sometimes referred to as giant cell tumor of the tendon sheath;: 100  diffuse TGCT is also called pigmented villonodular synovitis (PVNS). : 102

Classification
Classification for TGCT encompasses two subtypes that can be divided according to site – within a joint (intra-articular) or outside of the joint (extra-articular) – and growth pattern (localized or diffuse) of the tumor(s). : 100 : 361  Localized and diffuse subsets of TGCT differ in their prognosis, clinical presentation, and biological behavior, but share a similar manner of disease development. : 100

Localized TGCT
Localized TGCT is sometimes referred to as localized pigmented villonodular synovitis (L-PVNS), giant cell tumor of the tendon sheath (GCT-TS), nodular tenosynovitis, localized nodular tenosynovitis, and L-TGCT. : 1 : 100 The localized form of TGCT is more common. : 100 : 245  Localized TGCT tumors are typically 0.5 cm-4 cm),: 101  develop over years,: 100  are benign and non-destructive to the surrounding tissue, and may reoccur in the affected area. : 101  The most common symptom is painless swelling. : 101  Localized TGCT most often occurs in fingers, but can also occur in other joints. Diffuse TGCT
Diffuse TGCT is sometimes referred to as pigmented villonodular synovitis (PVNS), conventional PVNS, and D-TGCT.