Pterygium Unguis

Pterygium unguis, also known as a cutaneous horn, is an unusual and often striking skin growth. The name derives from its horn-like appearance, which is due to a conical or cylindrical projection of keratinized epidermal cells. The lesion can develop on any part of the body but is most common on the hands and fingers, particularly the nails. In this article, we will discuss the main definitions and types of pterygium unguis, as well as provide some insights into its diagnosis, causes, and treatments.

A cutaneous horn, or pterygium unguis, is a clinical presentation of a hyperkeratotic lesion that forms a conical projection above the skin surface. The base of the lesion is usually broad and flat, with a diameter of up to several centimeters. The length of the projection can vary from a few millimeters to several centimeters, and the color is typically brownish or yellowish. The lesion is made up of keratinized cells and can be easily detached from the underlying tissue. Pterygium unguis is not a true horn, as it lacks a bony core or a vascular supply.

Types

There are three main types of pterygium unguis: benign, premalignant, and malignant.

• Benign – Benign pterygium unguis is the most common type of cutaneous horn, and it is not usually associated with any underlying pathology. It is a harmless lesion that can be easily removed by surgical excision. Benign pterygium unguis is typically found in elderly patients, particularly those with a history of sun exposure.
• Premalignant – Premalignant pterygium unguis is a lesion that has the potential to become cancerous, although it is not yet malignant. It is characterized by a higher rate of cell proliferation and dysplasia than the benign type. Premalignant pterygium unguis is often found on sun-exposed areas, particularly in fair-skinned individuals. It is important to remove these lesions to prevent the development of squamous cell carcinoma, a type of skin cancer.
• Malignant – Malignant pterygium unguis is a rare type of cutaneous horn that has become cancerous. It is characterized by an aggressive growth pattern and invasion of the surrounding tissue. Malignant pterygium unguis is usually associated with squamous cell carcinoma, but other types of skin cancer, such as basal cell carcinoma and melanoma, have also been reported. Treatment usually involves surgical excision and may be followed by radiation therapy or chemotherapy.

Causes

The main causes of Pterygium unguis and their details.

1. Congenital Nail pterygium can be congenital, which means it is present at birth. Congenital pterygium unguis is a rare condition that is usually inherited as an autosomal dominant trait. The exact genetic basis of this condition is not well understood, but it is thought to be caused by a mutation in a gene that is responsible for the development of the nail bed.
2. Trauma Trauma is the most common cause of acquired nail pterygium. Traumatic nail pterygium is caused by repeated or severe injury to the nail bed, such as from nail biting, picking at the cuticles, or excessive manicuring. The injury causes the nail bed to become inflamed and form a thickened, hyperkeratotic tissue that adheres to the undersurface of the nail plate.
3. Infection Fungal infections of the nail, such as onychomycosis, can cause nail pterygium. Fungal infections can lead to thickening and deformation of the nail plate and the surrounding tissues. The infection can cause the nail bed to adhere to the undersurface of the nail plate, resulting in pterygium unguis.
4. Connective Tissue Disorders Connective tissue disorders, such as Ehlers-Danlos syndrome and Marfan syndrome, can cause nail pterygium. These disorders affect the connective tissues of the body, including those of the nail bed. The abnormal connective tissues can cause the nail bed to become adherent to the undersurface of the nail plate, leading to pterygium unguis.
5. Skin Conditions Skin conditions, such as psoriasis and lichen planus, can cause nail pterygium. These conditions can cause inflammation and thickening of the nail bed, leading to the formation of a hyperkeratotic tissue that adheres to the undersurface of the nail plate.
6. Medications Some medications can cause nail pterygium as a side effect. For example, retinoids, which are used to treat acne and other skin conditions, can cause nail pterygium. The exact mechanism by which these medications cause pterygium unguis is not well understood, but it is thought to be related to their effects on the nail bed and surrounding tissues.
7. Neoplastic Nail pterygium – can also be associated with certain types of cancer, such as squamous cell carcinoma and basal cell carcinoma. These cancers can cause the nail bed to become hyperkeratotic and adhere to the undersurface of the nail plate, resulting in pterygium unguis.
8. Inflammatory conditions – Various inflammatory conditions can contribute to the development of pterygium unguis. For example, psoriasis is a chronic skin condition that can affect the nails and cause changes in the nail matrix, which can lead to abnormal tissue growth and pterygium unguis. Similarly, lichen planus is a skin condition that can affect the nails and cause onycholysis, which can also contribute to the development of pterygium unguis.
9. Infectious diseases – Infectious diseases can also contribute to the development of pterygium unguis. For example, fungal infections of the nail, such as onychomycosis, can cause changes in the nail matrix and lead to abnormal tissue growth under the nail plate. Similarly, bacterial infections of the nail bed, such as paronychia, can cause inflammation and abnormal tissue growth.
10. Chemical exposure – Exposure to certain chemicals can also contribute to the development of pterygium unguis. For example, exposure to certain solvents or cleaning agents can cause damage to the nail matrix and lead to abnormal tissue growth. In some cases, chemical exposure may also cause onycholysis, which can contribute to the development of pterygium unguis.
11. Medications – Certain medications can also contribute to the development of pterygium unguis. For example, retinoids, which are commonly used to treat acne and other skin conditions, can cause changes in the nail matrix and lead to abnormal tissue growth. Similarly, chemotherapy drugs, which are used to treat cancer, can cause changes in the nail matrix and lead to the development of pterygium unguis.
12. Systemic diseases – Various systemic diseases can also contribute to the development of pterygium unguis. For example, systemic lupus erythematosus (SLE) is an autoimmune disease that can affect the nails and cause changes in the nail matrix, which can lead to abnormal tissue growth and pterygium unguis. Similarly, diabetes mellitus can affect the blood supply to the nail bed

Symptoms

The main list of symptoms for Pterygium unguis and explain them in detail.

1. Nail plate deformation: One of the most common symptoms of nail pterygium is nail plate deformation. The nail plate may appear to be misshapen, irregular, or curved. The deformity may be mild or severe, depending on the extent of the webbing. The nail plate may also be thicker than normal, making it difficult to cut or trim.
2. Translucent or opaque membrane: Another hallmark symptom of nail pterygium is the presence of a translucent or opaque membrane that covers part or all of the nail plate. The membrane is usually thin, but it can be thick in severe cases. It may be white or pink in color, and it can make the nail appear cloudy or hazy.
3. Proximal nail fold thickening: Pterygium unguis can cause the proximal nail fold to thicken and become inflamed. The proximal nail fold is the skin that sits at the base of the nail plate, and it provides nourishment to the nail matrix. In some cases, the thickening of the proximal nail fold can cause pain or discomfort.
4. Nail dystrophy: Pterygium unguis can also cause nail dystrophy, which is a term used to describe any abnormality in nail growth or development. Nail dystrophy can cause the nails to become brittle, discolored, or ridged. In severe cases, the nails may even separate from the nail bed.
5. Nail bed adherence: In some cases, the membrane of pterygium unguis can adhere to the nail bed, making it difficult to separate the two. This can cause pain and discomfort, and it may make it impossible to cut or trim the affected nail.
6. Nail bed hyperkeratosis: Nail bed hyperkeratosis is a condition in which the skin on the nail bed thickens and becomes rough. This can occur in cases of pterygium unguis, and it can make the nail plate appear even more deformed or irregular.
7. Nail clubbing: Nail clubbing is a condition in which the tips of the fingers become enlarged and the nails curve around the fingertips. This can occur in severe cases of pterygium unguis, and it may be a sign of an underlying medical condition.
8. Pain or discomfort: Pterygium unguis can cause pain or discomfort, especially if the webbing is severe. The thickening of the proximal nail fold or the adherence of the membrane to the nail bed can cause pain, and the irregular shape of the nail plate can be uncomfortable.

Diagnosis

Diagnosis: Pterygium unguis is usually diagnosed based on the clinical presentation, which includes the following features:

1. Triangular or trapezoidal tissue growth: The most characteristic feature of pterygium unguis is the presence of a triangular or trapezoidal tissue growth that extends from the proximal nail fold to the hyponychium. The growth can vary in size and thickness, and it may be translucent or pinkish in color.
2. Nail deformities: Pterygium unguis can cause various nail deformities, including nail thinning, ridging, and splitting. In severe cases, the nail may be completely absent or distorted.
3. Pain and discomfort: The growth can cause pain and discomfort, especially when pressure is applied to the affected area.
4. Family history: Pterygium unguis is a genetic condition that is often inherited in an autosomal dominant manner. Therefore, a family history of the condition can be an important diagnostic clue.

1. Histopathological examination: A biopsy of the nail and surrounding tissue may be performed to examine the tissue under a microscope. This test can help confirm the diagnosis of nail pterygium and rule out other conditions.
2. Blood tests: Blood tests may be ordered to rule out any underlying medical conditions that may be contributing to the nail deformity, such as autoimmune disorders or thyroid disease.
3. Dermoscopy: Dermoscopy is a non-invasive imaging technique that allows for a detailed examination of the nail and surrounding skin. This test can help identify any structural or color changes in the nail and rule out other conditions.
4. Culture and sensitivity tests: These tests are used to identify any bacterial or fungal infections that may be contributing to the nail deformity. A sample of the nail or surrounding tissue may be collected and sent to a laboratory for analysis.
5. Magnetic resonance imaging (MRI): MRI may be used to examine the soft tissues of the finger or toe and rule out any underlying structural abnormalities.

Tests: Although the diagnosis of pterygium unguis is usually based on clinical features, certain tests can be performed to confirm the diagnosis and rule out other conditions. These tests include:

1. Histological examination: A biopsy of the affected tissue can be taken and examined under a microscope to confirm the diagnosis of pterygium unguis. The biopsy can also rule out other conditions that can mimic the clinical features of pterygium unguis, such as glomus tumor, subungual exostosis, and squamous cell carcinoma.
2. Genetic testing: Genetic testing can be performed to confirm the presence of a genetic mutation that is associated with pterygium unguis. The most common mutation is in the HOXA13 gene, which plays a role in the development of the fingers and toes.
3. X-rays and MRI: X-rays and MRI can be used to visualize the underlying bone structure and soft tissues around the affected nail. These imaging tests can help rule out other conditions that can cause nail abnormalities, such as osteochondroma, enchondroma, and bone cysts.

Treatment

There are several treatments available for pterygium unguis, ranging from conservative measures to surgical intervention. In this article, we will discuss the main list of treatments for pterygium unguis and their details.

1. Conservative measures: Conservative measures involve non-invasive methods to alleviate symptoms and prevent further complications. The following are some of the conservative measures that can be taken for pterygium unguis:

a. Soaking the feet in warm water: Soaking the affected foot in warm water can help reduce pain and inflammation. It also softens the nail and surrounding skin, making it easier to trim the nail.

b. Trimming the nail: Trimming the nail straight across and avoiding rounded corners can prevent the nail from growing into the skin. However, it is important not to cut the nail too short, as this can worsen the condition.

c. Using over-the-counter pain relievers: Over-the-counter pain relievers, such as acetaminophen and ibuprofen, can help alleviate pain and reduce inflammation.

d. Wearing comfortable shoes: Wearing comfortable shoes with a wide toe box can prevent pressure on the toes and reduce the risk of ingrown toenails.

2. Antibiotics: Antibiotics may be prescribed if the ingrown toenail has become infected. Antibiotics can help fight the infection and prevent it from spreading to other parts of the body.
3. Surgery: If conservative measures and antibiotics are not effective, surgery may be required to remove the ingrown toenail. There are several types of surgical procedures that can be used to treat pterygium unguis:

a. Partial nail avulsion: Partial nail avulsion involves removing part of the affected toenail. This procedure is performed under local anesthesia and can be done in a doctor’s office. After the procedure, the patient may need to wear a dressing and avoid certain activities for a few days.

b. Total nail avulsion: Total nail avulsion involves removing the entire affected toenail. This procedure is also performed under local anesthesia and may require stitches. After the procedure, the patient may need to wear a dressing and avoid certain activities for several weeks.

c. Matrixectomy: Matrixectomy involves removing the nail matrix, which is the tissue that produces the nail. This procedure is typically reserved for severe cases of pterygium unguis or cases that have recurred multiple times. After the procedure, the patient may need to wear a dressing and avoid certain activities for several weeks.

d. Phenolization: Phenolization is a chemical procedure that involves applying phenol to the affected area to destroy the nail matrix. This procedure is typically used in cases where other surgical procedures have failed. After the procedure, the patient may need to wear a dressing and avoid certain activities for several weeks.

4. Laser treatment: Laser treatment is a relatively new and less invasive procedure for treating pterygium unguis. The laser is used to remove the affected tissue and promote healing. Laser treatment is typically reserved for mild to moderate cases of pterygium unguis.

a. Topical corticosteroids: Topical corticosteroids, such as clobetasol propionate or betamethasone dipropionate, can help reduce inflammation and swelling around the nail fold. These medications are applied directly to the affected area and are usually prescribed for short periods of time.

b. Topical retinoids: Topical retinoids, such as tretinoin or adapalene, can help improve the appearance of the nail by reducing hyperkeratosis (thickening of the skin) and promoting the growth of healthy tissue. These medications are also applied directly to the affected area and may take several months to show results.

c. Oral antibiotics: Oral antibiotics, such as doxycycline or erythromycin, may be prescribed if the nail pterygium is caused by an underlying bacterial infection. These medications help eliminate the infection and prevent it from spreading.

d. Nail splints or braces: Nail splints or braces may be used to support the affected nail and prevent it from further damage or deformity. These devices are usually custom-made and can be worn for several weeks or months.

Surgical treatments

Surgical treatments for nail pterygium are usually reserved for cases where conservative measures have failed or when the condition is causing significant pain, discomfort, or cosmetic concerns. The main surgical options for nail pterygium include:

a. Partial or complete nail avulsion: Partial or complete nail avulsion involves the removal of the affected nail, along with the underlying nail bed and matrix. This procedure is usually performed under local anesthesia and can be done in an outpatient setting. It may take several months for a new nail to grow back.

b. Nail matrixectomy: Nail matrixectomy involves the removal of a portion of the nail matrix, which is responsible for nail growth. This procedure is typically performed under local anesthesia and can be done in an outpatient setting. Nail matrixectomy may be recommended for severe cases of nail pterygium, where the nail is significantly deformed or damaged.

c. Laser therapy: Laser therapy involves the use of a high-intensity laser to vaporize the nail pterygium tissue. This procedure is usually performed under local anesthesia and can be done in an outpatient setting. Laser therapy may be recommended for cases of mild to moderate nail pterygium.

In conclusion, there are several treatments available for pterygium unguis, ranging from conservative measures to surgical intervention. Conservative measures include soaking the feet in warm water, trimming the nail, using over-the-counter pain relievers, and wearing comfortable shoes. Antibiotics may be prescribed if the ingrown toenail has become infected. Surgical procedures, such as partial nail avulsion, total nail avulsion, matrixectomy, and phenolization, may be required if conservative measures and antibiotics are not effective.

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