Epithelioma
Synonyms and keywords: Pilomatrixoma; Calcifying Epithelioma of Malherbe; Epithelioma cuniculatum; Carcinoma cuniculatum; Superficial epithelioma

# Overview
Epithelioma is an abnormal growth of the epithelium, which is the layer of tissue that covers the surfaces of organs and other structures of the body.

# Historical Perspective
- Epithelioma cuniculatum was first discovered by Aird et al. in 1954.
- Epithelioma cuniculatum is derived from the words epithelioma, meaning "tumor of the epithelium," and cuniculate, referring to crypt-like spaces seen on histology that resemble rabbit burrows.

# Classification
- The term epithelioma is usually considered for skin tumors originating from the epithelial origin also known as carcinoma cutis. However, epithelial tumors can arise from any epithelial lining of the organs including ovarian, uterine, glands, prostate, thyroid, lacrimal gland among others
- Epithelioma may be classified according to nature of tumor into 2 sub-types:
Benign growths
Malignant carcinomas
Basal cell carcinoma
Squamous cell carcinoma
Mixed or squamo-basal
- Benign growths
- Malignant carcinomas
Basal cell carcinoma
Squamous cell carcinoma
Mixed or squamo-basal
- Basal cell carcinoma
- Squamous cell carcinoma
- Mixed or squamo-basal
- Basal and the squamous cell carcinomas are the most common types of epithelioma's

# Pathophysiology
- On gross pathology, bulky exophytic mass are characteristic findings of epithelioma. However there is a variance in the presentation of epithelioma
- Clinical picture can range anywhere from superficial to deep, simple papillary to nodular appearance, fungoid, ulcerated, or cauliflower shaped
- On microscopic histopathological analysis, endophytic and exophytic growth pattern, histiocytes, eosinophils, plasma cells, hyperchromasia, and mitoses are characteristic findings of epithelioma.

# Causes
- Epithelioma of the skin may be caused by;
trauma
Chronic irritation
HPV infection
Prolonged sun exposure
Occupational exposure to tar and certain oils
Pre-cancerous dermatosus - these are the benign skin lesions that develop as a result of trauma or any other condition that may serve as a base for development of epithelial skin cancers. examples include;
Senile Keratosis
Leukoplakia
Radiation dermatitis
Xeroderma
Cutaneous horns
Old scars
Chronic ulceration
Warts
Sebaceous cysts
Pigmented nevi
Psoriatic or eczematous lesions
SLE skin lesions
Lupus vulgaris
- trauma
- Chronic irritation
- HPV infection
- Prolonged sun exposure
- Occupational exposure to tar and certain oils
- Pre-cancerous dermatosus - these are the benign skin lesions that develop as a result of trauma or any other condition that may serve as a base for development of epithelial skin cancers. examples include;
Senile Keratosis
Leukoplakia
Radiation dermatitis
Xeroderma
Cutaneous horns
Old scars
Chronic ulceration
Warts
Sebaceous cysts
Pigmented nevi
Psoriatic or eczematous lesions
SLE skin lesions
Lupus vulgaris
- Senile Keratosis
- Leukoplakia
- Radiation dermatitis
- Xeroderma
- Cutaneous horns
- Old scars
- Chronic ulceration
- Warts
- Sebaceous cysts
- Pigmented nevi
- Psoriatic or eczematous lesions
- SLE skin lesions
- Lupus vulgaris

# Differentiating Epithelioma from other Diseases
- Epithelioma must be differentiated from other diseases that cause skin masses, such as:
- Seborrheic keratosis with sebaceous differentiation
- Sebaceous hyperplasia
- Sebaceous adenoma
- Sebaceous carcinoma

# Epidemiology and Demographics

## Age
- Epithelioma is more commonly seen in older patients more than 50 years of age. Incidence in age 55 to 75 is 100 times higher as compared to 20 years old.

## Gender
- Males are more commonly affected with epithelioma as compared to females.

## Race
- Epithelioma is seen more commonly in Caucasians.
- Not common in dark skinned people

# Risk Factors
- Common risk factors in the development of epithelioma are trauma, chronic irritation, and HPV infection, prolonged sun exposure as well as occupational exposure to tar and certain oils. An additional risk factor is the presence of benign skin conditions called pre-cancerous dermatosus which include warts,dermatitis, leukoplakia, eczematous or psoriatic liesions, sebborhic keratosis, SLE skin lesions, nevi and cutaneous horns.

# Natural History, Complications and Prognosis

## Prognosis
- The prognosis of the epithelioma is variable, depending on the type, location, extent and stage at the time of diagnosis and hence treatment.
- However, most of the epitheliomas can be treated easily and the prognosis is good

# Diagnosis

## Symptoms
- Epithelioma of the skin can present in any form, usually easy to diagnose. Some of the presentations may include:
New mole/growing mole/mole changing color
New or growing warty lesion
Painless swelling
Indurated or ulcerated lesion
Chronic scar that starts bleeding or changing
- New mole/growing mole/mole changing color
- New or growing warty lesion
- Painless swelling
- Indurated or ulcerated lesion
- Chronic scar that starts bleeding or changing
- Epithelial tumors of the organs can present in any way ranging from swelling or mass to symptoms related to involved organ system

## Physical Examination
- Physical examination for epithelioma of the skin may be remarkable for:
Non tender swelling
Hard, waxy nodules with pearly borders
Ulceration or Induration
- Non tender swelling
- Hard, waxy nodules with pearly borders
- Ulceration or Induration

## Laboratory Findings
- There are no specific laboratory findings associated with epithelioma. However tests can be performed to rule out other causes of skin lesions like syphilis, lupus vulgaris, allergies etc.

## Other Diagnostic Studies
- Any suspicious skin lesion should be biopsied. Histopathology is the most accurate way of diagnosing a skin condition or identifying or ruling out a malignancy of the skin.

# Treatment
There is no single method of treatment since treatment procedure and extent depends upon the location and extent as well as the stage of the tumor along with the age and the sex of the patient. Some common treatment methods include
- Surgical excision
- Irraditation
- Electrocauterisation
- Combination Therapy- Surgery plus electrocauteristaion plus irradiation
Involves curreting the lesion under local anesthesia followed by cauterization of the base by the chemical method(zinc chloride or nitrate) followed by irradiation
- Involves curreting the lesion under local anesthesia followed by cauterization of the base by the chemical method(zinc chloride or nitrate) followed by irradiation
- Combination therapy - Surgery plus radiation (usually used in case of advanced tumors with metastasis or infilltration)
Some other treatment options include:
- Cryosurgery
- Podophyllin
- Treatment with tissue extract
- Chemosurgery - usually for recurrent basal cell epitheliomas