What Is Squamous Papilloma?
Squamous or squamous cell papilloma is a benign exophytic overgrowth associated with human papillomavirus infection. It arises from the squamous cells found beneath the tissue that forms the skin surface, digestive and respiratory tract passages, and the lining of the abdominal organs. It is the most common papillary lesion of the oral cavity. It occurs most commonly on the base of the tongue and the tonsils; less commonly on the hard palate, gums, tip of the tongue, pharynx, epiglottis, esophagus, respiratory tract, conjunctiva, and uvula. Squamous papillomas on the skin are known as verrucas or warts. Whereas the squamous papillomas occurring on the genital tract are referred to as genital warts.
It is most commonly diagnosed during adulthood. Females are more commonly affected than men. It is a benign overgrowth but its potential to transform into a malignant overgrowth is yet to be studied. It is usually asymptomatic, but as the lesions overgrow, it may cause some discomforting symptoms. A provisional diagnosis could be made with the clinical features, but a biopsy is required to have a definitive diagnosis.
What Causes Squamous Papilloma?
The exact cause of the condition is sometimes unclear; however, it is typically associated with the human papillomavirus. HPV 6 and 11 are most commonly associated with this condition. Even though all HPV lesions are highly infective and contagious, the squamous papilloma appears to have low virulence and infectivity rate. It also does not seem to be contagious.
What Are the Different Types of Squamous Papilloma?
The two main different types of squamous papilloma include;
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Oral Squamous Cell Papilloma: Squamous cell papilloma is the most common benign lesion of the oral cavity. It accounts for 2.5 percent of all oral cavity lesions. HPV is the main cause of oral squamous cell papilloma. It is most commonly found on the tongue, cheeks, and lips. It mostly does not mutate to become malignant growths nor overgrow and spread to other body parts. It is most commonly diagnosed between the ages of 30 and 50. It is generally asymptomatic and does not require any treatment unless it causes pain and interferes with eating.
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Conjunctival Squamous Cell Papilloma: Conjunctival squamous papilloma is an acquired noncancerous squamous cell tumor of the conjunctiva, the clear tissue that covers the white part of the eye. It is also referred to as infectious conjunctival papilloma since human papillomavirus is the main cause of this condition. HPV 6 and 11 are associated with the development of conjunctival papilloma. It is most commonly seen in children and young adults who are younger than 20 years. People with skin warts are at high risk of getting conjunctival papilloma. In some instances, the infection may be acquired at birth, where an infected mother transmits the HPV virus to the child during childbirth. It is painless and causes no vision problems. The lesion often resolves spontaneously and does not require any treatment. But if treatment is required, the treatment options include surgical excision with medical treatment and cryotherapy.
What Are the Clinical Features of Squamous Papilloma?
It most commonly appears as a solitary lesion with a soft, pedunculated mass (supported on a stalk or stem) and numerous finger-like projections. The finger-like projections can be short or long and rounded if keratin is accumulated around the lesion. The maximum size of the lesion is about 0.5 centimeters with no or little thereafter. Squamous papilloma affecting the larynx is rare and can obstruct breathing. It also causes hoarseness of voice. Less keratinized squamous cell papilloma lesions are red or pink in color and look similar to a raspberry. Whereas highly keratinized lesions are white in color and resemble the look of the head of the cauliflower.
How Is Squamous Papilloma Diagnosed?
The provisional diagnosis of squamous papilloma is attained by examining the clinical features. However, a biopsy is recommended by healthcare providers to attain a definitive diagnosis of the condition. In a biopsy, a small amount of tissue sample is removed from the affected area using a needle. The removed sample is then sent to the laboratory for pathological examination. The histological features revealed by the biopsy can help distinguish squamous papilloma from other cancerous lesions.
A PCR (polymerase chain reaction) test may be recommended to detect the strains of human papillomavirus associated with the condition.
What Are the Histopathological Features of Squamous Papilloma?
The histopathological features of squamous papilloma include;
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The proliferation of keratinized stratified squamous epithelium appears as finger-like projections with fibrovascular connective tissue.
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The connective tissue may exhibit inflammatory changes.
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The keratin layer is highly thickened.
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Epithelium shows a normal maturation pattern.
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Occasionally the lesions may exhibit basilar hyperplasia (an increase in the number of basal cells) and mitotic activity.
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Dysplastic features may be seen.
What Are the Treatment Options for Squamous Papilloma?
Squamous papilloma is mostly asymptomatic and requires no treatment. However, in some cases, the condition may be more extensive and symptomatic and requires treatment. The treatment options for squamous papilloma include;
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Surgical Excision: Surgical excision is the most common treatment for squamous papilloma. Surgical excision for squamous papilloma involves the removal of the head and base of the lesion without damaging or removing the surrounding healthy tissues.
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Cryotherapy: Cryotherapy is a treatment procedure in which extreme cold temperatures are used to freeze and remove abnormal tissue. In cryotherapy, substances like liquid nitrogen, argon gas, and liquid nitrous oxide create intense cold temperatures and remove abnormal tissue.
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Laser Ablation: Laser ablation refers to removing abnormal tissue by irradiating the skin surface using a laser beam. It has several advantages, including wound sterilization, successful hemostasis, being devoid of sutures, and minimal post-operative pain and edema.
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Medications: Topical salicylic compounds are used to treat squamous papilloma. In addition, medications like 5-Fluorouracil and topical interferon alpha-2b are used to treat conjunctival papilloma.
What Are the Differential Diagnosis of Squamous Papilloma?
The differential diagnosis of squamous papilloma are;
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Veruca Vulgaris: Veruca vulgaris is a common skin wart that is caused by human papillomavirus. It predominantly occurs in children and young adults. Clinically it appears as cauliflower-like papules with a hyperkeratotic and papillomatous surface. It is difficult to distinguish verruca vulgaris from squamous papilloma.
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Condyloma Acuminatum: Condyloma acuminatum is a benign squamous cell proliferative lesion caused by the human papillomavirus. It is also known as genital warts since it is most commonly found in the genital areas.
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Verruciform Xanthoma: Verruciform xanthoma is a rare oral cavity lesion with a wart-like appearance, but it may also appear sessile, polypoid, or papillomatous. It may also appear on the penis and the scrotum. The exact cause is unknown, but some cases are associated with human papillomavirus.
Conclusion
Squamous papilloma is a benign condition, and its potential for malignant transformation is yet to be studied. It is usually asymptomatic and does not require any treatment. But treatment may be required in severe cases where the lesion grows extensively and causes symptoms. Treatment options include surgical excision, cryotherapy, laser ablation, and medication. It is highly treatable and mostly does not recur.
