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From fever to skin nodules: How do erythematous nodules reveal health risks step by step?
Erythema nodosum, an inflammatory condition characterized by inflammation of subcutaneous adipose tissue. The condition causes painful red or blue nodules on the skin, often appearing symmetrically on the calves, legs, arms, and other parts of the body. Although the causes of erythematous nodules vary, approximately 20% to 50% of cases are idiopathic. The good news is that this condition usually resolves automatically within 30 days.
Signs and symptoms of erythematous nodules
Incubation period
Early signs of erythematous nodules are often accompanied by flu-like symptoms such as fever, cough, fatigue, and joint pain. Some people may also experience joint stiffness or swelling and weight loss.
Outbreak period
During an outbreak, erythematous nodules are characterized by 1 to 2 inches (about 25 to 51 mm) nodules under the skin, usually on the lower legs. Although these nodules can appear anywhere on the body, the most common places are on the calves, arms, legs, and trunk. Each nodule usually disappears in about two weeks, although new nodules may continue to form for up to six to eight weeks.
Generally, each nodule heals completely without leaving scars in about two weeks.
Joint pain and inflammation sometimes continue for weeks or months after the nodule appears. Lesser variants of erythematous nodules include the ulcerative form and the stagnant form.
Causes of erythematous nodules
Idiopathic
About 30% to 50% of cases of erythematous nodules are idiopathic, that is, the specific cause cannot be determined.
Infection
Infections associated with erythematous nodules include:
- Streptococcal infections, especially among children
- Many granulomatous microbial infections, including tuberculosis and leprosy
- Mycoplasma pneumonia
- Cryptococcosis
- Many other pathogens
Autoimmunity
An autoimmune disease associated with erythematous nodules is Behçet disease. In addition, pregnancy and certain medications may trigger the onset of this disease.
Cancer
Certain cancers such as non-Hodgkin lymphoma and pancreatic cancer are associated with erythematous nodules.
Pathophysiology of erythematous nodules
Erythematous nodules may be a delayed hypersensitivity reaction to multiple antigens. Although circulating immune complexes are found in patients with inflammatory bowel disease, they are not found in idiopathic or uncomplicated cases.
Diagnosis of erythematous nodules
The diagnosis of erythematous nodules mainly relies on clinical manifestations. In certain cases of uncertainty, a biopsy may be taken for microscopic examination. Typical findings under the microscope include:
- Neutrophil infiltration around capillaries, resulting in septal thickening
- Radial granuloma with surrounding stellate fissures
Treatment of erythematous nodules
Erythematous nodules are usually self-limiting and most resolve spontaneously within 3 to 6 weeks. Treatment focuses on the underlying cause, and symptoms can be relieved with bed rest, leg elevation, compression bandages, and nonsteroidal anti-inflammatory drugs (NSAIDs).
NSAIDs are often more effective in the early stages of erythematous nodules.
In certain cases of persistent disease, potassium iodide may be used. For severe refractory cases, corticosteroids and colchicine may be used.
Epidemiology
Erythematous nodules are the most common form of steatitis, occurring mainly in the 20- to 30-year-old age group, and are three to six times more common in women than in men.
Conclusion
Understanding the causes, symptoms, and diagnosis of erythematous nodules is critical to early detection of potential health problems. When facing such symptoms, have you ever thought about the real cause of your health condition?
