Erythema Induratum of Bazin
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- Erythema induratum of Bazin (EIB) is a chronic, nodular eruption that usually occurs on the lower legs of otherwise heavyset women.
- EIB is a cutaneous manifestation of tuberculin hypersensitivity in association with Mycobacterium tuberculosis infection (e.g., tuberculoid).
- Currently, the term “nodular vasculitis” (NV) is often used as a synonym for EIB, although some authors make a distinction between the two conditions.
- EIB for lesions secondary to mycobacteria
- NV for noninfectious variant (e.g., Crohn disease)
- EIB most closely resembles erythema nodosum (EN) because there is overlap in clinical presentation and histologic features.
- After treatment of any identified potential etiologies, therapeutic options are similar for both EIB and EN, which are forms of panniculitis.
- Although NV is quite common, erythema induratum is rare other than in India, Hong Kong, and some areas of South Africa.
- Most common (86%) form of cutaneous TB (tuberculid) in Hong Kong found between 1993 and 2002
- Predominant age: 13 to 66 years (mean 37 years)
- Predominant sex: female (80–90%) > male
Etiology and Pathophysiology
- The morphologic, molecular, and clinical data suggest that EIB and NV represent a common inflammatory pathway, that is, a hypersensitivity reaction (type III or IV) to endogenous or exogenous antigens, such as the tubercle bacillus.
- A causal relationship between EIB and TB is circumstantial and based on the following:
- High degree of hypersensitivity to purified protein derivative (PPD), often marked
- Frequent personal or family history of TB
- Presence of active TB foci
- Occasional coexistence with other tuberculids in the same patient
- Response to anti-TB treatment
- Results from the enzyme-linked immunosorbent assay–based (interferon-γ release assays or IGRA), such as QuantiFERON-TB Gold In-Tube and T-SPOT TB blood tests commonly are positive in patients with EIB.
- EIB has been associated with other atypical mycobacteria including Mycobacterium avium, Mycobacterium monacense, Mycobacterium massiliense, and Mycobacterium chelonae.
No known genetic predisposition
- Prior or current infection with M. tuberculosis
- Age <40 years
- Female gender
- Bacillus Calmette-Guérin (BCG) vaccination
- Residence in Asia (e.g., especially India and Hong Kong) and South Africa
- Hepatitis C
- Crohn disease
- BCG vaccination has reduced cases of M. tuberculosis infection worldwide. However, vaccine risks include complications, such as subcutaneous abscesses including EIB, localized or generalized cutaneous tuberculids, local inflammation, fever, and spread of TB to distant organs.
- Safe sex precautions, including condom use
- Counsel regarding not sharing needles in order to prevent HIV or hepatitis C transmission.
Commonly Associated Conditions
- A past or present history of TB at an extracutaneous site occurs in about 50% of patients.
- Pulmonary TB (PTB) is most common.
- TB cervical lymphadenitis is the next most common.
- Important to consider if HIV infection is present when TB and NV are present
- Other tuberculoids (e.g., lupus vulgaris)
- Hepatitis C