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

• Histoplasmosis-Associated Erythema Nodosum

What is Erythema Nodosum due to Histoplasmosis? (Definition/Background Information)

• Erythema nodosum is a skin condition that causes painful red subcutaneous nodules. It may be caused by numerous factors including certain medications, infectious diseases, pregnancy, inflammatory bowel disease, blood cancer, and many other disorders
• Erythema Nodosum due to Histoplasmosis occurs in a background of histoplasmosis, an infection caused by inhaling the spores of a fungus. The infection primarily affects the respiratory system (lung and airways), but may involve other parts of the body when severe
• The nodules in Erythema Nodosum due to Histoplasmosis may occur on the legs and the arms. The signs and symptoms of Histoplasmosis may include tightness of chest, cough, fever, fatigue, and muscle and joint pain
• Adequate treatment of the underlying infection can help resolve Erythema Nodosum due to Histoplasmosis. With appropriate treatment of histoplasmosis, the prognosis of erythema nodosum is good in a majority of individuals

Who gets Erythema Nodosum due to Histoplasmosis? (Age and Sex Distribution)

• Erythema Nodosum due to Histoplasmosis may occur at any age. However, older adults and young children are known to develop histoplasmosis more often
• Both males and females are affected
• It can affect individuals of any ethnicity, race or region. But, the fungal infection is more common in parts of North America and South America

What are the Risk Factors for Erythema Nodosum due to Histoplasmosis? (Predisposing Factors)

• Individuals with histoplasmosis are at an increased risk for developing Histoplasmosis-Associated Erythema Nodosum
• It is reported that individuals with a weak immune system have an increased risk for infection

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 Erythema Nodosum due to Histoplasmosis? (Etiology)

• Research scientists believe that Erythema Nodosum due to Histoplasmosis is caused by an immunological response of the body to histoplasmosis infection. The nodules form on skin as a reaction to the underlying condition
• Histoplasmosis is caused by the fungus Histoplasma capsulatum, in a majority of the cases. The infection usually affects the lung, but can also involve other areas of the body
• The infection is spread by bird and bat droppings, which is transmitted to humans through inhalation. The fungal spores enter the human body through inhalation and affects the respiratory system causing an infection

What are the Signs and Symptoms of Erythema Nodosum due to Histoplasmosis?

The signs and symptoms of Erythema Nodosum due to Histoplasmosis may include:

• Presence of nodules beneath the skin
• They begin as flat, firm, deep red lesions, and often become elevated  measuring up to an inch on the body
• After a few days, the nodules turn purple; weeks later, they become flat and brownish patches
• The symptoms of histoplasmosis may include coughing, breathing difficulty, fever, muscle and joint pain, etc.
• The nodules may be present on any part of the body, most frequently on the skins and ankles, also higher on the  on the legs, thighs, and buttocks and forearms

Histoplasmosis does not cause any significant signs and symptoms in most individuals with good and healthy immune systems. It resolves spontaneously, leaving behind small characteristic calcifications visible on X-rays. Patients treated with certain medications affecting the immune system can have reactivation of old histoplasmosis, with systemic consequences.

How is Erythema Nodosum due to Histoplasmosis Diagnosed?

The following procedures may be used to diagnose Erythema Nodosum due to Histoplasmosis:

• Thorough evaluation of the individual’s medical history and a complete physical examination
• Culture of body fluids, such as sputum, to identify the fungus causing histoplasmosis
• Detection of histoplasma antigen in urine
• Blood test to measure antibodies in blood against the fungus
• Chest X-rays and CT scans
• Tissue biopsy, if necessary: A skin/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

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 Erythema Nodosum due to Histoplasmosis?

• Major complications associated with skin lesions of Erythema Nodosum due to Histoplasmosis are not reported
• However, complications are mainly observed due to the underlying histoplasmosis infection. Severe infection can involve other regions of the body, particularly in those with a suppressed immune system

How is Erythema Nodosum due to Histoplasmosis Treated?

The treatment options of Erythema Nodosum due to Histoplasmosis include treating the underlying histoplasmosis, which is undertaken through:

• Administration of antifungal medication
• Symptomatic and supportive therapy, if needed
• Specific treatments for the pain and swelling of erythema nodosum include NSAIDs, systemic corticosteroids, and iodine, used as a medication
• On treating the underlying condition, erythema nodosum skin lesions usually resolve

How can Erythema Nodosum due to Histoplasmosis be Prevented?

The prevention of Erythema Nodosum due to Histoplasmosis is linked to preventing the associated histoplasmosis, which may be enabled through the following measures:

• Undertaking early diagnosis and treatment of histoplasmosis, especially in individuals with poor immune function
• In the endemic regions, individuals with weak immune system should avoid exposure to soil in areas with high risk of fungal spores and avoid exploring bat caves. Buildings which have housed nesting birds, such as barns, are also possible exposure sites
• Getting treatment for any underlying medical condition(s) that may decrease immunity in the individual

What is the Prognosis of Erythema Nodosum due to Histoplasmosis? (Outcomes/Resolutions)

• The prognosis for Erythema Nodosum due to Histoplasmosis is usually good with prompt treatment of histoplasmosis
• However, the overall prognosis is dependent on the underlying infection, the severity of the symptoms presented, and the health status of the individual

Additional and Relevant Useful Information for Erythema Nodosum due to Histoplasmosis:

• 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
• The presence of dirt on the body is not a causative factor for the condition. However, it helps to be clean and hygienic, which may help the condition from getting worse