Paranasal sinuses are pneumatic cavities located at the level of the facial bones surrounding the nasal pits, with which they communicate through the nasal meati. These structures are coated with respiratory mucosa (cyliated  pseudostratified cyliated cylindrical  epithelium).
Schematically it  can be said that:
A. The ethmoidal sinus (formed by the anterior and posterior hetmoidal cells)   at birth consists of small niches and develops progressively over the years up to the age  of 5 years;
B. The jaw sine  is present from birth and grows by about 2 mm. per year until the age of  12-15 years;
C. The frontal sine has a slow growth until the age of   11.  It  then proceeds  to growth more  rapidly until the age of 20;
D. Sphenoid breasts begin to grow from birth and continue until puberty reaching  its final size at the age of  18.
The pathologies  that most  frequently affect the paranasal sinuses, are acute or chronic inflammatory ones, that is: sinusitis.
These pathological frameworks can be classified into:
1. Acute sinusitis: duration less than three weeks; they resolve without residual damage at the level of the sinus mucosa;
2. Subacute sinusitis: duration between three weeks and three months;
3. Chronic sinusitis: duration more than three months and characterized by irreversible damage to the mucous membrane.
With anatomo-pathological criterion they can be classified into:
1. Catarrhal acute sinusitis; 2. Acute muco-purulent sinusitis;3. Acute purulent sinusitis;4. Acute ulcer-necrotic sinusitis;5. Chronic catarrhal sinusitis;6. Chronic purulent sinusitis;7. Chronic hypertrophic-adenomatous sinusitis. As for pathogenes, sinusitis is classified into:I. Rhinogene: the infection reaches the breasts from the nasal meati (it is the most frequent: about 85 percent of cases);II. Odontogene: it affects the mascellar sinus through an osteomyelitis of the alveolar wall, through an apical granuloma or a caries of a tooth whose root protrudes in the jaw sinus (they represent less than 10 percent of sinusitis);III. Hematogens: as a result of exanthematic diseases or batteriemia;IV. Traumatic: for direct trauma with or without fracture and hemogen;V. From foreign substances: by penetration of substances from nasal cavities (such as infected water);VI. Barotraumatic: caused by an obstacle that prevents the establishment of a balance between nasal and sinus pressure as occurs in aviators, divers, palombari, etc. There are local, general and environmental predisposition factors to the phlogosis of paranasal sinuses. All those that contribute to the decrease in the drainage capacity of the sinus cavities are local factors, totally or partially obstructing the drenagio blockage (deviation of the nasal septum, hypertrophy of the lower swirls, medium paradoxical swirl, boily concage, ostic-meatal complex edema, hypertrophic ethmoidal bulla). General factors are those alterations that decrease the overall resistance of the organism (general diseases such as diabetes, hormonal alterations, alterations in electrolyte balance. Or vitamin deficiencies or inadequate diets; or diseases that cause immunodeficiency). Environmental factors are those conditions that decrease the ciliary activity (exposure to cold, dry environment, environmental pollution, active or passive cigarette smoking). Both the obstruction of the drainage ostium, and the decrease in ciliary activity, result in the accumulation of secretions inside the breasts. Secretion becomes infected very easily and, associated with the phlogistic-edematous process of the mucous membrane, further prevents sinus drainage. This creates a vicious circle that self-maintains the disease. The microbial agents most frequently called into question are:A. In acute sinusitis: Streptococcus Pneumonia, Hemophilus Influenzae and Moraxella Catarrhalis. Other agents are Staphilococco Aureus, Streptococcus Beta-hemolytic, Klebsiella Pneumoniae and Psedomonas Aeruginosa.B. In chronic sinusitis:Among the aerobic germs: Staphilococco Aureus, Moraxella Catarrhalis and Haemophilus sp. Among the anaerobic germs: Prevotella, Porphiromonas and Fusobacterium sp. Clamydia Pneumoniae seems to have an important role to play recently.Among the viruses that can cause sinusitis the most important are Rhinovirus, influenza and parainfluenza virus, coronavirus, adenovirus, respiratory syncial virus, echovirus and coxsackie virus. In recent years there has been an increase in mycotic infections (which have a more insidious clinical trend than those from bacterial or viral infections) probably due to the increase in presuption factors such as: congenital and acquired immunodeficiency syndromes, radiotherapy, immunosuppressive therapies, antibiotic therapies or protracted corticosteroids, diabetes. The most frequently affected paranasal sinuses are:1. In adults: the mascellar, ethmoidal, frontal and sphenoid breasts;2. In children: ethmoidal breasts in newborns, and jaw breasts around 3-4 years of life. As for symptomatology, acute sinusitis is manifested by deaf, continuous, more violent pain in the morning for the night stagnation of secretions. Often there is an exacerbation of pain related to the movements of the head or triggered by pressure exerted on certain points of the face. There is nasal obstruction and rhinorrhea, generally unilateral (only 20 percent of cases have bilateral rhinorrhea), purulent or anterior or posterior muco-purulent. Hyposmia/anosmia, closed rhoolalia or nasal voice. General malaise, fever, asthenia. The diagnosis is based on clinical history (frequently patients report a previous flu syndrome or acute rhinitis) and on the objective examination with anterior and posterior rhinoscopy (better if with optical fiber), oropharyngoscopy, palpation of sinus trigger points, culture examination of secretion and CT of paranasal sinuses in axial and coronal projection. Treatment consists in facilitating breast drainage and eliminating infection and inflammation. So: antibiotic therapy for no less than 10-14 days, with antibiotics suggested by cultivation examination; treatment with decongestants and nasal vasoconstrictors (which contribute to reducing edema and facilitating sinus drainage); anti-inflammatory drugs such as NSAIDs (with analgesic, anti-inflammatory and antipyretic action) or corticosteroids (with antiedemigena action). The absence of a response to treatment and an ingravescent clinical picture, high-risk or immunosuppressed patients or the suspicion of intracranial complications, require hospitalization. In chronic sinusitis, surgery is indicated.