Erythema induratum
back to main page
Erythema induratum (Latin: erythema induratum, most commonly referred to as Bazin's erythema induratum) is a chronic, recurrent inflammatory disease of the subcutaneous tissue classified into the group of adipose tissue inflammations (panniculitis). The condition is characterized by the formation of painful, deeply located nodules and inflammatory infiltrates, which most commonly develop on the lower legs, especially on their posterior surface. In some cases, the lesions may break down and lead to the formation of difficult-to-heal ulcers. In the past, erythema induratum was primarily associated with Mycobacterium tuberculosis infection, but it is now known that the disease can also have an immunological basis, and its development depends on the interaction of many factors. Diagnosis requires differentiation from numerous dermatological and vascular diseases and confirmation by histopathological examination.
Erythema induratum - what it is
Erythema induratum belongs to the group of lobular panniculitis with accompanying vasculitis. This means that the inflammatory process primarily involves the deep adipose tissue located under the skin, and at the same time, damage occurs to the vessels supplying this tissue.
The classic form of erythema induratum of Bazin is considered a delayed-type hypersensitivity reaction to tubercle bacilli antigens. However, active tuberculosis is not found in many patients, but only a past infection or positive immunological test results indicating contact with the bacillus. For this reason, it is increasingly emphasized nowadays that erythema induratum is a disease with a complex immunological mechanism.
Factors contributing to the development of the condition include, among others:
- chronic venous insufficiency,
- microcirculation disorders,
- reduced immunity,
- past infection with tubercle bacilli,
- chronic inflammatory states of the body,
- disorders of the functioning of the immune system.
The disease is significantly more common in women than in men, most often between the ages of 20 and 50. It runs a chronic course, with periods of exacerbation and remission.
Erythema induratum - what it looks like
The clinical presentation of erythema induratum is relatively characteristic, although in the early stages it may resemble many other skin diseases.
Typical lesions include:
- deeply located nodules ranging in diameter from a few millimeters to several centimeters,
- firm, clearly palpable subcutaneous infiltrates,
- redness or bluish-purple discoloration of the skin,
- tenderness to pressure,
- local increase in skin temperature.
As the inflammatory process progresses, the nodules may:
- coalesce into larger foci,
- undergo necrosis,
- break down with the formation of ulcerations,
- leave atrophic scars and discoloration.
A characteristic feature of erythema induratum is a chronic course. Individual lesions may persist for many weeks or months, and after their resolution, subsequent foci often appear.
Histopathological examination most commonly reveals:
- lobular panniculitis,
- granulomatous inflammatory infiltrates,
- fat necrosis,
- vasculitis of medium and small vessels.
Histopathological examination remains one of the most important elements confirming the diagnosis.
Erythema induratum - where it appears
The most typical location of erythema induratum is the posterior surfaces of the lower legs, especially the calf area. This is an area exposed to chronic venous and lymphatic circulation disorders, which can favor the development of inflammatory lesions.
The most common locations include:
- posterior surfaces of the lower legs,
- lateral surfaces of the calves,
- ankle areas,
- less commonly the thighs.
Exceptionally, lesions may also appear on:
- buttocks,
- forearms,
- arms,
- other areas of the limbs.
The lesions usually occur bilaterally, although their distribution may be asymmetrical.
Unlike many other skin diseases, erythema induratum practically never affects:
- the face,
- the scalp,
- mucous membranes,
- hands and feet.
The location of the lesions is an important diagnostic clue and helps to distinguish the disease from other forms of panniculitis.
Erythema induratum - how to distinguish from erysipelas and other dermatoses
Diagnosis of erythema induratum requires careful differentiation, because many diseases present with painful redness of the lower limbs.
Most often, the following are considered:
Disease | Most important features |
|---|---|
Erythema induratum | Deep nodules, chronic course, possible ulcerations |
Erysipelas | Acute bacterial infection with high fever, sharply demarcated erythema |
Erythema nodosum | Painful nodules on the anterior surface of the lower legs, no ulcerations |
Connective tissue inflammation (cellulitis) | Diffuse infection of the skin and subcutaneous tissue with severe inflammation |
Nodular vasculitis | Histological picture differing from erythema induratum |
Necrotizing vasculitis | Often presence of hemorrhagic lesions and systemic symptoms |
The following are used in diagnostics:
- a detailed medical history,
- dermatological examination,
- skin biopsy with histopathological assessment,
- laboratory tests,
- tests for tuberculosis (IGRA or tuberculin skin test),
- imaging studies if active infection is suspected.
Correct diagnosis is crucial because treatment depends on the cause of the disease. In the case of coexisting mycobacterial infection, antitubercular treatment is necessary, whereas in forms unrelated to tuberculosis, anti-inflammatory therapy and treatment of coexisting diseases are used.
Erythema induratum - triggering factors and recurrences
Erythema induratum is chronic in nature, which is why periodic recurrences of the disease are observed in many patients. Exacerbations occur especially when factors promoting microcirculation disorders or immune system activation persist.
The most commonly described triggers include:
- chronic venous insufficiency,
- venous stasis of the lower limbs,
- prolonged standing,
- low temperatures and cooling of the limbs,
- infections,
- chronic inflammatory foci,
- reduced immunity,
- coexisting autoimmune diseases.
The risk of recurrence can be reduced by:
- treating venous insufficiency,
- maintaining a healthy body weight,
- regular physical activity to improve circulation,
- using compression therapy in individuals with venous stasis,
- treating chronic infections and inflammatory states,
- regular dermatological check-ups.
Since erythema induratum can be a manifestation of systemic diseases, every case requires comprehensive diagnostics and an individual treatment plan managed by a dermatologist, and if necessary, also an infectious disease specialist, angiologist, or rheumatologist.
