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

• IGD (Interstitial Granulomatous Dermatitis)

What is Interstitial Granulomatous Dermatitis? (Definition/Background Information)

• Interstitial Granulomatous Dermatitis (IGD) is a form of granulomatous dermatitis, an uncommon skin condition that presents asymptomatic skin rashes mostly in middle-aged women with autoimmune disorders, mainly rheumatoid arthritis
• The cause of development of Interstitial Granulomatous Dermatitis is not clearly understood. But, IGD is associated with autoimmune diseases, use of certain medications, such as antihypertensives, and even malignancies
• The treatment of Interstitial Granulomatous Dermatitis is based on the signs and symptoms, which may wax and wane, and the associated condition. In some cases, a spontaneous resolution of IGD is noted within a few weeks to months

Who gets Interstitial Granulomatous Dermatitis? (Age and Sex Distribution)

• Interstitial Granulomatous Dermatitis is a rare condition that is generally observed in middle-aged women
• It may affect individuals of other age groups as well
• Both males and females are known to be affected
• The condition may affect individuals of all racial and ethnic groups

What are the Risk Factors for Interstitial Granulomatous Dermatitis? (Predisposing Factors)

The risk factors for Interstitial Granulomatous Dermatitis may include:

• Autoimmune diseases: A strong association with autoimmune disease is reported, notably rheumatoid arthritis. Other autoimmune conditions include systemic lupus erythematous (SLE), autoimmune hepatitis, antiphospholipid syndrome, autoimmune thyroiditis, Behcet's disease, and Churg-Strauss syndrome
• Other conditions associated with IGD include chronic uveitis, pulmonary paracoccidioidomycosis, and pulmonary silicosis
• An association with certain medications, especially antihypertensives, is observed. Other involved medication types include anticonvulsants, antidepressants, antihistamines, lipid-lowering agents, and TNF-alpha blockers
• Association with malignancy, such as leukemia and lung cancer, is rarely reported

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 Interstitial Granulomatous Dermatitis? (Etiology)

The cause of formation of Interstitial Granulomatous Dermatitis (IGD) is unknown. The granulomatous lesions are believed to develop as a reactive process of the body to certain antigens in the body.

• This condition is typically noted in individuals with a previous history of autoimmune conditions, most commonly rheumatoid arthritis (RA). In such cases, it is known as Interstitial Granulomatous Dermatitis Arthritis (IGDA)
• IGD is also frequently associated with antihypertensives, such as ACE inhibitors, beta blockers, calcium channel blockers, and diuretics, and other medications. In such cases, it is known as interstitial granulomatous drug reaction

What are the Signs and Symptoms of Interstitial Granulomatous Dermatitis?

In a majority of individuals, Interstitial Granulomatous Dermatitis presents asymptomatic skin lesions. The signs and symptoms may include:

• Presence of numerous papules and plaques
• These granulomatous skin lesions may range in color from buff-colored to pink to red
• Most of the lesions are located in the upper trunk, armpits, or upper limbs (closer to the shoulders); a symmetrical distribution may be observed
• Rope sign: It is a characteristic feature of IGD wherein linear, cord-like nodular skin rashes are noted
• The rashes may be round or annular too
• Sometimes, the lesions may present mild itching to burning sensation
• The skin lesions may be present for several days to months; a waxing and waning of the lesions may be noted

Additional signs and symptoms of the associated condition, if any present, may be noted.

How is Interstitial Granulomatous Dermatitis Diagnosed?

The following tests and exams may be used in diagnosing Interstitial Granulomatous Dermatitis (IGD):

• Evaluating the clinical history (physical exam) and a thorough family history (including history of autoimmune disease and current medication use)
• Dermoscopy: It 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
• KOH tests to rule out a fungal infection
• Skin tissue biopsy: A tissue 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

Tests and procedures to diagnose the associated condition, if any present, is important.

A differential diagnosis to eliminate other skin conditions may be needed before arriving at a definitive diagnosis. These may include:

• Erythema elevatum diutinum
• Erythema multiforme
• Granuloma annulare (it may closely resemble IGD)
• Lichen planus
• Palisading neutrophilic granulomatous dermatitis
• Rheumatoid neutrophilic dermatosis
• Rheumatoid nodules
• Rheumatoid vasculitis

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 Interstitial Granulomatous Dermatitis?

The complications of Interstitial Granulomatous Dermatitis are not very significant, but may include the following:

• Emotional stress
• Cosmetic concerns
• Relapse of the condition

Complications of the underlying/associated condition, if any, may be noted.

How is Interstitial Granulomatous Dermatitis Treated?

There is no standard treatment for Interstitial Granulomatous Dermatitis (IGD) but treating the underlying/associated condition (autoimmune disease) is important. In some cases, no treatment may be necessary as IGD may improve and resolve on its own.

The treatment measures for IGD may include:

• Use of topical steroid creams and ointments
• Local injections of corticosteroids
• Oral and systemic steroids, if necessary
• Administration of medications such as dapsone, hydroxychloroquine, and methotrexate

In case of a drug reaction causing Interstitial Granulomatous Dermatitis, discontinuation of the causative medication may result in a cure, or in improvement of the condition.

How can Interstitial Granulomatous Dermatitis be Prevented?

Currently, there are no specific preventative measures available for Interstitial Granulomatous Dermatitis.

• Adequately treating any underlying autoimmune disorder may lower the risk for IGD
• Medications that cause IGD as a side effect may be discontinued and/or alternative medication prescribed

What is the Prognosis of Interstitial Granulomatous Dermatitis? (Outcomes/Resolutions)

• Interstitial Granulomatous Dermatitis may resolve itself spontaneously within a few weeks to months in some cases
• Adequately treating the underlying associated autoimmune disease or stopping the offending medication may help mitigate the condition

Additional and Relevant Useful Information for Interstitial Granulomatous Dermatitis:

Cleaning the skin too hard with strong chemicals or soaps may aggravate the skin condition. Care must be taken avoid strong soaps and chemicals that could potentially worsen the condition.