Benign tumors of nose and sinuses
Benign neoplasm of nasal cavity and sinuses are rather uncommon. Benign lesions are usually smooth, localized and covered with mucous membrane.
Squamous papilloma of nose and sinuses:
Lesions similar to that of warts in skin can be seen arising from the vestibule of the nose. They can also occur in the lower part of the nasal septum. These lesions could be single, multiple or pedunculated.
Etiologically papillomas are considered to be caused by viral infections. Human papilloma viruses have been implicated. Papillomas have been categorized on anatomical basis into four types:
Keratotic papilloma - Involves the skin lined nasal vestibule
Inverted papilloma - Involving the lateral nasal wall
Fungiform papilloma involving the nasal septum
Cylinderical papilloma - Arising from paranasal sinuses
Histological classification:
Histologically papillomas can be classified into:
Squamous papilloma:
Histologically squamous papilloma arises from the stratified squamous epithelium lining of the vestibule of the nose. It is characterized by epithelial proliferation which grows in an exophytic manner with formation of multiple papillar fronds, with very few mitosis with very little or no nuclear atypia. Squamous papillomas are unilateral and unlike inverted papilloma are not premalignant with no bone destruction.
Histological features that could predict recurrence of the lesion include:
1. Epithelial atypia
2. Epithelial mucin production
Nearly a third of all papillomas of nose are known to recur after surgery. Radical excision is the preferred treatment modality of these lesion.
Inverted papilloma:
Synonyms: Schneiderian papilloma, Benign papilloma of nasal cavity, Inverted papilloma.
Definition: The mucosal lining of nose and para nasal sinuses is known as Schneiderian membrane, in memory of Victor Conrod Schnider who described its histology. Papillomas arising from this membrane is very unique in that they are found to be growing inwardly and hence the term inverted papilloma. These papillomas are unique in their history, biology and location.
Papillomas involving the vestibule is not included under this group because histologically, biologically and behaviour wise it is different.
The lining mucosa of nose and paranasal sinuses is unique embryologically in the sense that it is derived from the ectoderm, in contrast to the lining epithelium of laryngobronchial tree which is derived from endoderm.
Inverted papillomas behave like neoplasms, arising from reserve / replacement cells located at the basement membrane of the mucosa. The stimulus for this proliferation is unknown. The resulting thickening of the epithelium assumes an inverting, fungiform or combination growth pattern. Depending on the degree of metaplasia varying amounts of respiratory / cylinderical cells may be seen in schneiderian papilloma. Rarely the papilloma may be composed entirely of cylinderical cells, and hence the term cylinderical cell papilloma is used to describe this subtype.
Anatomic classification of Schneiderian papilloma: Inverted papilloma can be classified according to its site of occurance i.e. lateral wall and septal papillomas. They show differences in their behavior patterns. The septal papillomas remain confined to the nasal septum and may very rarely involve the roof and floor of the nasal cavity. Carcinomatous transformation is rare in septal papillomas. Papilloma of lateral wall is known to involve multiple sites i.e. floor, roof of nasal cavity, para nasal sinuses and naso lacrimal duct. Carcinomatous transformation is common in this variety.
Clinical classification of inverted papilloma was proposed by Krouse. He used his classification and staging protocol to decide on the optimal treatment modality of these patients.
Krouse classification:
T1 - The disease is limited to the nasal cavity alone T2 - Disease is limited to ethmoid sinuses and medial and superior portions of maxillary sinuses T3 - Disease involves the lateral or inferior aspects of maxillary sinus or extension into frontal or sphenoid sinuses T4 - This stage involves tumor spread outside the confines of nose and sinuses. This stage also includes malignancy
Incidence: Inverted papillomas are fairly common occurring in 1 - 50 of patients with nasal polypi. If all nasal polypi removed surgically are tested histopathologically then the incidence could be still more higher. Men are affected more commonly than women. The age of affliction may range from between second to seventh decade of life. The mean age of presentation being 50.
Etiology: Human papilloma virus has been implicated as a causative factor in these patients. This infection in association with mutation of genes may cause papillomas. Coinfection with Herpes simplex virus may interact with Human papilloma virus to cause inverted papilloma.
Role of imaging in the diagnosis of inverted papilloma: CT scan is necessary for determining the optimal surgical approach in managing these patients. It also has the added advantage of differentiating other mass lesions involving the nasal cavities. Classically inverted papillomas occupies the middle meatus and lateral nasal wall with areas of higher density associated with bony sclerosis. If contrast is used for CT imaging contrast enhancement is also seen.
MRI: Is very useful when the tumor has extrasinosal involvment or show malignant transformation. It also helps in the differentiation of tumor tissue from inflammatory mucosa.
Gross apprearance: Nasal papillomas show two architectural patterns: 1. Papillary and exophytic 2. Inverted with inwardly invaginating epithelial growth into underlying stroma. A combination of both patterns also can occur. The papillary form tends to commonly occur in the nasal septum, while the inverted form often occurs in the lateral wall of the nose and sinuses.
Microscopy: The papillary form also known as fungiform papilloma shows epithelial proliferation over a thin core of connective tissue. Inversion of epithelial masses is usually not present. In the case of inverted papilloma the predominant growth is directed inwards into the underlying stroma. The stroma is not breached in these patients. When they undergo malignant transformation the stroma is found to be breached. The predominant cell type in these papillomas is epidermoid in nature. Intercellular bridges can be clearly demonstrated. Microscopic mucous cysts can also be identified in both these types. Keratinisation is very minimal. Excessive keratinisation is very rare, and should prompt the pathologist to other diagnosis like malignant transformation.
Clinical features: Patients present with unilateral nasal mass, commonly fleshy in nature. Sometimes it may occur behind a sentinel nasal polyp. It commonly involves the nasal cavity, erodes the medial wall of maxilla and may present inside the maxillay sinus.
Symptoms: are usually caused by compression of adjacent structures like orbit, pterygopalatine fossa, base of skull or soft tissues.
1. Unilateral nasal obstruction 2. Nasal bleeding 3. Nasal discharge 4. Proptosis if lamina papyracea is breached
Management: Surgical removal provides cure in most of the cases. Recurrence is common in 20% of patients. It is commonly removed pervia naturalis. If the mass is huge then lateral rhinotomy will have to be resorted to for complete removal.
Complications:
1. Haemorrhage
2. Malignant transformation
Pleomorphic adenoma:
This is one of the most common benign tumors of major salivary glands. It can also occur in the minor salivary glands which are known to exist in the nasal cavity. Intranasal pleomorphic adenoma usually originates from glands of the nasal septal mucosa. Studies reveal that most of these glands are found in the lateral nasal wall and concha.
Pathogenesis:
This still remains rather unknown. The septal origin of the tumor could be due to misplaced embryonic ectoderm cells, a remnant of the vomeronasal organ. It could also be induced by viral infection.
Nasal pleomorphic adenomas differ from that of major salivary gland pleomorphic adenomas since they contain high cellularity with a low stroma. These tumors lack a capsule. Histopathology and immunohistochemical examination are the only ways to arrive at the diagnosis.
These patients usually present with nasal obstruction, and occasional nasal bleed. Rarely there could be nasal deformity and nasal swelling associated with pain.
Management:
Ideally excision biopsy should be performed. The mass can be accessed endoscopically or via lateral rhinotomy route.
Schwannoma:
Nearly half of the schwannomas arise in the head and neck region. In the paranasal sinuses, they can arise from the ophthalmic / maxillary divisions of the trigeminal nerve or from the branches of the autonomic nervous system. The maxillary and ethmoidal sinuses are more commonly involved. Sphenoid sinus schwannoma have also been reported.
Symptoms:
Symptoms involving schwannomas involving paranasal sinuses vary according to the site, nerve of origin, compression to adjacent structures. Lesions can also present as nasal polyp.
Imaging CT/MRI of nose and sinuses will be useful in surgical planning.
Meningioma:
Meningiomas affecting nose and sinuses are rather rare. These tumors occur as a result of extension from primary intracranial sites. Signs and symptoms associated with nasal meningioma include:
Nasal obstruction
Nasal secretion
Presence of nasal polypi
Maxillary pain
Periorbital oedema
Exophthalmia
Proptosis
Vision loss
Head ache
These lesions are ideally managed by surgical excision and submitting the tissue for histopathological examination.
Imaging helps not only in the diagnosis but also in planning the surgical procedure.
Hemangiomas:
These lesions could present as epistaxis. The types of hemangiomas involving nose include:
Capillary hemangioma (also known as bleeding polypus of nasal septum):
This is a soft reddish pedunculated / sessile tumor arising from the anterior portion of nasal septum. Usually these lesions are smooth, but could get ulcerated and present with recurrent epistaxis and nasal obstruction. Ideally it should be excised along with a cuff of normal health mucoperichondrium.
Cavernous hemangioma:
These lesions ideally arise from the tubrinate tissues and the lateral nasal wall. These lesions can be managed either by excision / cryotherapy.
Chondromas:
These are benign tumors arising from nasal cartilages. Nasal chondromas are rather rare, and almost always arises from the nasal septum. This is actually a benign cartilaginous neoplasm. Condromas could arise from the following areas in the nose and sinuses:
Ethmoid sinus - 50%
Maxilla - 18%
Nasal septum - 17%
Sphenoid sinus - 6%
Alar cartilage - 3%
These lesions generally appear as smooth, firm and lobulated masses.
These lesions can be managed surgically by excision of the mass. These lesions are slow growing. They could also present with severe epistaxis.
Juvenile nasopharyngeal angiofibroma:
These highly vascular lesions are seen almost exclusively in adolescent males. These masses are known to begin from the sphenopalatine foramen and could present with intractable severe epistaxis. This topic is dealt with in detail elsewhere.
Intranasal meningoencephalocele:
This is herniation of brain tissues and meninges through foramen caecum or cribriform plate of ethmoid bone. Clinically these lesions present as smooth polypoidal mass in the upper portion of the nasal cavity between the nasal septum and the middle turbinate. It is commonly seen in young infants and children. Significant identification of this mass is the presence of cough reflex or increase in the size of the mass during crying / straining.
If not examined properly this lesion can be mistaken for polyp and could even be avulsed leading on to CSF leak and meningitis.
Imaging is crucial in making a correct diagnosis.
Treatment is by frontal craniotomy, excising the stalk from the brain with repair of dural and bony defect. Intracranial mass can be removed at a subsequent procedure after closure of the defect.
Nasal gliomas:
These are congenital, non malignant cell rests of neuroglial tissue. They present as a craniofacial mass. In other words these lesions are composed of heterotopic mass of neuroglial tissue. These masses are considered to be the consequence of incomplete closure of anterior fontanelle between the nasal and frontal bones. This results in an abnormal connection between embryonic ectodermal and neuroectodermal elements. Eventhough these lesions are benign in nature, they are cosmetically and clinically unfavorable. These lesions hence should undergo total surgical excision. Early surgical intervention will prevent craniofacial distortion.
Theory that accounts for the formation of nasal gliomas:
Encephalocele theory:
This theory states that encephaloceles and gliomas develop secondarily due to a failure of regression of the forebrain dural protrusion through foramen cecum.
CT and MR imaging helps in the diagnosis and surgical treatment plan.
