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

• Duncan’s Dirty Dermatosis
• TFFD (Terra Firma-Forme Dermatosis)

What is Terra Firma-Forme Dermatosis? (Definition/Background Information)

• Terra Firma-Forme Dermatosis (TFFD) is an asymptomatic skin condition of childhood characterized by the appearance of dirty brown patches on skin, due to an abnormal process of keratinization (in which the outer skin surface, the stratum corneum, turns into a hard and dark-pigmented protective layer in the background of any trauma)
• The cause of Terra Firma-Forme Dermatosis is not known (idiopathic), but it is not due to poor personal hygiene. The thick dirt-like skin patches cannot be removed by washing with soap and water. TFFD is also known as Duncan’s Dirty Dermatosis. The condition responds very well to topical application (i.e., rubbing of the skin patches with isopropyl alcohol)

Who gets Terra Firma-Forme Dermatosis? (Age and Sex Distribution)

• Terra Firma-Forme Dermatosis is generally observed in children, adolescents, and young adults. According to medical literature, the condition is under-reported, and it may be prevalent in a wider age group of individuals
• Both males and females are affected
• Worldwide, there is no racial or ethnic preference observed

What are the Risk Factors for Terra Firma-Forme Dermatosis? (Predisposing Factors)

• Currently, no risk factors are clearly identified for Terra Firma-Forme Dermatosis
• The dirty skin rashes are typically known to appear in spring and summer following sun exposure

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s 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 Terra Firma-Forme Dermatosis? (Etiology)

The cause of Terra Firma-Forme Dermatosis (TFFD) is presently not well understood.

• Some research experts consider TFFD to be an abnormal form of delayed keratinization which results in the formation of brown-black discolored skin patches
• According to some medical literature, this skin condition may be a variant of confluent and reticulated papillomatosis of Gougerot and Carteaud

What are the Signs and Symptoms of Terra Firma-Forme Dermatosis?

The signs and symptoms of Terra Firma-Forme Dermatosis (TFFD) may include:

• Presence of brown-gray-black skin patches in the form of papules and plaques
• These pigmented patches are irregular and velvety
• The thick skin lesions appear as dirt patches on the body, even though the individual has good hygiene and cleanliness
• In most of the cases, the neck is involved; however, TFFD lesions have been observed on the face, chest, back, abdomen, umbilicus, pubis, and scalp region
• Rarely, the skin rashes may be found spread across the body surface (extensive involvement of skin)
• In some individuals, the skin rashes have been found at surgical sites such as the knee (after knee replacement surgery) and midline of chest (after heart surgery)

There is no accompanying pain, irritation, or discomfort of any sort from these skin patches.

How is Terra Firma-Forme Dermatosis Diagnosed?

A diagnosis of Terra Firma-Forme Dermatosis (TFFD) may involve the following exams and procedures. The diagnosis may be arrived at by rubbing the affected area with 70% isopropyl alcohol, which will reveal normal skin below.

• Physical examination of the individual and medical history evaluation
• Skin tests for fungal infection, if necessary
• Dermoscopy: Dermoscopy is a diagnostic tool where a dermatologist examines the skin using a special magnified lens
• Wood’s lamp examination: In this procedure, the healthcare provider examines the skin using ultraviolet light. It is performed to examine the change in skin pigmentation
• Skin biopsy: A skin biopsy is performed and sent to a laboratory for a pathological examination. The pathologist examines the biopsy under a microscope. After putting together clinical findings, special studies on tissues (if needed) and with microscope findings, the pathologist arrives at a definitive diagnosis. A skin tissue biopsy is usually not performed in TFFD

A differential diagnosis may be considered to eliminate other skin conditions that may present similar signs and symptoms. These may include:

• Acanthosis nigricans
• Atopic dirty neck
• Confluent and reticulated papillomatosis of Gougerot and Carteaud
• Dermatitis neglecta
• Epidermal nevus
• Pityriasis versicolor
• Post-inflammatory hyperpigmentation
• Seborrheic keratosis
• Symmetrical acrokeratoderma

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 Terra Firma-Forme Dermatosis?

The possible complications due to Terra Firma-Forme Dermatosis include:

• Severe emotional stress due to cosmetic issues
• Extensive involvement of the trunk region
• Social isolation due to dirty appearance implying poor personal hygiene
• Superimposed bacterial and fungal skin infections
• Treatment complications

How is Terra Firma-Forme Dermatosis Treated?

The treatment measures available for Terra Firma-Forme Dermatosis include:

• Use of topical application 70% isopropyl alcohol is curative. Forcefully wiping/rubbing the dirt-like skin patches with alcohol swabs helps in complete removal of the pigmented patches. Typically, no other treatment measures are necessary
• Application of mild keratolytic agents, such as salicylic acid, for extensive skin patches may be considered
• Use of chemical peels
• Providing reassurance to parents and affected children

How can Terra Firma-Forme Dermatosis be Prevented?

Currently, there are no preventative measures available for Terra Firma-Forme Dermatosis.

What is the Prognosis of Terra Firma-Forme Dermatosis? (Outcomes/Resolutions)

• The prognosis of Terra Firma-Forme Dermatosis is generally excellent with appropriate treatment (rubbing and cleaning the affected skin surfaces with isopropyl alcohol)
• The condition is asymptomatic, benign, and no recurrences are generally noted following suitable treatment

Additional and Relevant Useful Information for Terra Firma-Forme Dermatosis:

The following DoveMed website link is a useful resource for additional information:

https://www.dovemed.com/healthy-living/skin-disorders/