What are the other Names for this Condition? (Also known as/Synonyms) 

• Degos Acanthoma
• Pale Cell Acanthoma

What is Clear Cell Acanthoma of Skin? (Definition/Background Information)

• Clear Cell Acanthoma of Skin is a benign (non-cancerous) slow-growing tumor of the skin. It is not an uncommon skin lesion
• Usually a single lesion is observed, which is characterized by a red, shiny, dome-shaped bump or patch. It most commonly occurs on the legs
• Clear Cell Acanthoma of Skin is typically seen in individuals over 40 years of age. It may be surgically removed, if bleeding occurs or for cosmetic reasons
• The prognosis is generally good as it is a benign tumor that remains stable for many years

Who gets Clear Cell Acanthoma of Skin? (Age and Sex Distribution)

• Clear Cell Acanthoma of Skin is common in middle-aged and older individuals (generally in adults over the age of 40 years)
• It is slightly more common in women than men
• The condition is seen worldwide, across all races and ethnicities

What are the Risk Factors for Clear Cell Acanthoma of Skin? (Predisposing Factors)

• Currently, there are no known risk factors of Clear Cell Acanthoma of Skin
• However, adults above 40 years are at a greater risk of this benign condition

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Clear Cell Acanthoma of Skin? (Etiology)

The cause of Clear Cell Acanthoma of Skin is presently unknown. Some researchers believe that it may be due to a reactive inflammation (skin reaction) to unknown triggers.

What are the Signs and Symptoms of Clear Cell Acanthoma of Skin? 

Clear Cell Acanthoma of Skin is generally asymptomatic (i.e., no signs and symptoms are seen). However, the following may be observed:

• Presence of a characteristic skin lesion; commonly it is present as a single skin lesion
• The Clear Cell Acanthoma is usually a pink to red, shiny, dome-shaped bump (nodule). Sometimes, it is present as a patch on the skin
• The size of the lesion is usually less than 2 cm
• It has a clear boundary, which makes it identifiable from the surrounding normal skin. It frequently has a “stuck on” appearance
• Sometimes crusting, bleeding, or ulceration may be seen. In some cases, the surface may be ulcerated giving the appearance of pyogenic granuloma (another skin condition)
• Clear Cell Acanthoma is commonly observed on the legs; it may also occur on the abdomen, scrotum, etc.
• These lesions grow very slowly and become visible/noticeable, any time after 2-10 years
• Sometimes, it is associated with other skin conditions (such as stasis dermatitis, seborrheic keratosis, bacterial or skin condition, varicose vein, etc.)

How is Clear Cell Acanthoma of Skin Diagnosed?

The following procedures may be used to diagnose Clear Cell Acanthoma of Skin:

• Thorough evaluation of the individual’s medical history and a complete physical examination, including of the skin
• During history-taking the physicians may want to know the following:
  • When the symptoms began and whether they are becoming worse
  • One’s personal and family history of skin diseases, birth moles, etc. 
• A consultation with the dermatologist is often necessary, who are the experts in dealing with skin diseases/conditions. A diagnosis may be made based on its characteristic appearance
• Sometimes, when the diagnosis is not clear, or if there is a suspicion of other skin conditions, additional tests may be necessary:
  • Dermatoscopy (or dermascopy) is a non-invasive device that helps magnify the skin lesions for a closer look, by the performing specialist
  • Skin biopsy: In this procedure, the physician removes a sample of the skin tissue and sends it to the laboratory for a histopathological examination. The pathologist examines the biopsy under a microscope. The pathologist arrives at a definitive diagnosis after a thorough evaluation of the clinical and microscopic findings, as well as by correlating the results of special studies on tissues (if required)             

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Clear Cell Acanthoma of Skin?

The complications of Clear Cell Acanthoma of Skin include:

• In most individuals, there are no complications associated with this condition
• However, in some individuals the lesion may ulcerate and bleed
• Cosmetic issues may arise requiring the need of medical attention by skin specialists

How is Clear Cell Acanthoma of Skin Treated?

The treatment options of Clear Cell Acanthoma of Skin include:

• Most individuals need no treatment, as these lesions are benign and remain stable for a long period of time
• Surgical excision may be required for cosmetic reasons or to address complications, such as due to bleeding. In such cases, a complete excision of the lesion is curative
• Other procedures that may be employed to remove the lesion include Mohs microscopic surgery, cryotherapy, CO2 laser removal, etc.

The healthcare provider will recommend the best treatment options based upon one’s individual health circumstances.

How can Clear Cell Acanthoma of Skin be Prevented?

Currently, there is no known method of preventing Clear Cell Acanthoma of Skin occurrence. However, these are non-cancerous, stable, skin lesions.

What is the Prognosis of Clear Cell Acanthoma of Skin? (Outcomes/Resolutions)

The prognosis of Clear Cell Acanthoma is excellent with or without surgical removal of the tumor. The tumor is benign and mostly remains stable over time.

Additional and Relevant Useful Information for Clear Cell Acanthoma of Skin:

Biopsy microscopic findings: The tumor consists of proliferation of cells with pale staining cytoplasm. The lesion may be acanthotic, exophytic, or psoriasiform. The classical features include a sharp demarcation from adjacent normal squamous epithelium and adnexal structures. Focally, parakeratosis or ulceration may be noted. In the areas of ulceration, neutrophilic collections may be seen.

• Histochemical stains: The cells of the lesion contain abundant glycogen and hence, may be positive with PAS, but negative with PAS with diastase
• Immunohistochemical stains: The tumor is positive for Involucrin and negative for carcinoembryonic antigen (CEA). Due to negativity of CEA, the tumor is probably not of a sweat gland origin
• Genetic and molecular findings: No specific genetic or molecular findings is reported so far

Differential diagnosis may include, but is not limited to:

• Dermatofibroma
• Eccrine poroma
• Melanoma
• Psoriasis
• Pyogenic granuloma
• Seborrheic keratosis
• Verruca vulgaris

Even though clinically eccrine poroma can resemble Clear Cell Acanthoma; histologically, eccrine poromas are composed of small cuboidal cells that do not have a clear cytoplasm.