Sarcoidosis of Upper Respiratory Tract: An Overview

Introduction:

The upper respiratory tract is composed of portions like the nose, mouth, larynx, and voice box. The function of the upper respiratory tract is to help in the process of gaseous exchange. These portions help in functions like speech, cough, and swallowing. Any obstruction in the upper respiratory tract is responsible for symptoms of breathing difficulties. Sarcoidosis of the upper respiratory tract is associated with obstruction of the airway due to the formation of granulation tissues.

What Is Sarcoidosis?

Sarcoidosis is a multisystem disorder characterized by the presence of multiple granulomas in different organs. This is an extremely rare disorder and is seen in 11 out of 10000 individuals. Young individuals are most commonly affected by this condition. The commonly involved organs are the lungs, skin, eyes, and joints. In some cases, organs like the heart, kidneys, central nervous system, and exocrine glands are involved.

• Cause of Sarcoidosis:

The causative factors are unknown. But the association of metal exposure like beryllium, and dust exposure is seen in many cases. Also, infection due to microorganisms like mycobacteria and propionibacteria are considered potential risk factors. The expression of various inflammatory mediators is associated with the formation of granulomas in these conditions. Genetic factors are also responsible for the development of such conditions. Several HLA and non-HLA alleles are identified as associated with sarcoidosis.

All these factors lead to an immune pathway activation. This immune pathway initiates an immune feedback loop. Several antigen-presenting cells like dendritic cells, alveolar macrophages, and alveolar epithelial cells are activated through these mechanisms. As a result, monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factors, and interleukins are secreted. The inflammatory mediators are associated with the activation of CD4+ T lymphocytes. These T lymphocytes are responsible for the secretion of chemical mediators like interferon-gamma, interleukin-4, and interleukin-13. These chemical mediators are linked to the formation of granulomas in sarcoidosis. Also, CD4+ T lymphocytes are differentiated in T helper cells which is responsible for the formation of granulomas.

• Clinical Features of Sarcoidosis:

The clinical features of sarcoidosis are:

1. The lung is the most commonly involved organ in such cases. Patients often complain of breathing difficulties, dry cough, wheezing during respiration, and chest pain. In severe cases, accumulation of the fluid in the pleura (pleural effusion) and collection of air outside (pneumothorax) of the lung can also be seen. In severe cases, fibrosis of the lungs can also be observed.

2. The most common manifestation of sarcoidosis is skin lesions. Papules/plaques (circumscribed, elevated, and solid) and subcutaneous nodules (abnormal growth of the tissue beneath the skin) can be found. Skin lesions often appear hyper or hypopigmented. These skin lesions often show redness or yellowish discolorations. This skin growth is found in the hands, feet, and necks.

3. The second most common feature of sarcoidosis is the involvement of the ocular tissues. Inflammation of the middle third of the eye (uvea) is the most common clinical feature of this condition. Patients often complain of loss of vision, redness, and pain in the eye. Apart from this, other ocular inflammations like conjunctivitis (inflammation of the white protective layer of the eye), scleritis (inflammation of the sclera), and inflammation of the lacrimal gland can also be seen.

4. Inflammation of the joints is seen in around 15 percent of the cases. Pain in the large joints is seen most commonly. Sometimes involvement of the small joints of the hands can also be seen. These all are caused by loss of bone structure due to bone mineral loss.

5. Involvement of the liver in such conditions is relatively less. In most cases patients are asymptomatic, and alteration of liver function can be detected through liver function tests. Nodules can be detected within the liver in imaging modalities or in liver biopsies. Other than this, features of portal hypertension (increased pressure of portal circulation) and enlarged liver can also be visible.

6. In the kidney formation of renal stones and the deposition of calcium in the kidney can be observed.

What Are the Features of Sarcoidosis of Upper Respiratory Tract (SURT)?

The clinical presentation of Sarcoidosis of the upper respiratory tract is following:

1. Nose: Patients often complain of nasal stiffness and nasal blockage. Also, loss of smell sensation and the presence of hard crust can be seen. Nose bleeding and difficulty in swallowing are also present sometimes. Sometimes this condition may involve the nasal septum and sinuses. Destruction of the nasal septum due to the growth of the granulation tissue can be observed. This may lead to nose deformities and septal perforations. Involvement of the sinus may lead to idiopathic facial pain and heaviness in the face in the affected portion. In some rare cases, involvement of the sinus may lead to peripheral nerve involvement, salivary gland extension, and extension in the cranium. The involvement of the paranasal sinus in sarcoidosis is known as Sino nasal sarcoidosis.

2. Laryngeal Involvement: This is a potentially serious condition. This lead to respiratory depression and breathing difficulties due to the narrowing of the airway tube. Involvement in the voice box may cause difficulty in speech and a change in the voice.

3. Endobronchial Involvement: Laryngeal involvement may further lead to endobronchial involvement. In this condition narrowing of the proximal airways can be seen. In this condition, erythematous mucosal thickening of the airway tube can be seen. Respiratory sounds like wheezing, squeaks, and stridor can also be heard in such conditions.

What Are the Diagnostic Methods for Sarcoidosis of the Upper Respiratory Tract?

The Diagnostic test for sarcoidosis of the upper respiratory tract are:

1. Radiological examination of the nose, paranasal sinuses, and chest can be done. The presence of the nodules in the chest can be visible.

2. Evaluation of the biomarkers like the estimation of serum angiotensin-converting enzyme and evaluation of the antineutrophil cytoplasmic antibody can be done. An elevated level of angiotensin-converting enzyme in the blood can be seen.

3. Gallium-67 (67Ga) scanning can be done to detect sarcoidosis and for the detection of paranasal sinuses.

4. Computed tomography imaging of the chest and high-resolution computed tomography (HRCT) of the chest can be done for the detection of chest involvement.

5. The biopsy examination of the larynx and the proximal respiratory tract will show the presence of the granulation tissues.

What Are the Treatment of Sarcoidosis of the Upper Respiratory Tract?

The treatment protocol for sarcoidosis of the upper respiratory tract is based on the severity of the disorder.

1. In mild cases, topical application through inhalation can be helpful to reduce inflammation. Intralesional steroid injections can be used in laryngeal sarcoidosis.

2. In moderate cases, systemic application of steroids such as Prednisolone is continued for two to six months. Methotrexate, Azathioprine, Infliximab, Leflunomide, and Hydroxychloroquine can be used as steroid-sparing agents in cases where the steroid is not acting.

3. In case of severe cases of laryngeal sarcoidosis airway maintenance can be done through a tracheostomy procedure. Surgical removal of lesions through carbon dioxide laser can be done. Endoscopic sinus surgeries can be done to remove lesions in the sinus.

Conclusion:

Sarcoidosis is an inflammatory disorder of unknown etiology. The presence of granuloma is the hallmark feature of this condition. Involvement of the upper respiratory tract is a rare manifestation of sarcoidosis. Patients often complain of symptoms like nose blockage, nose bleeding, and breathing difficulties in such cases. Mild to moderate cases can be treated by the administration of steroids. In severe cases, surgical interventions are required.