What is the appropriate workup for vasculitis?

From the Guidelines

Vasculitis workup should include a combination of clinical assessment, laboratory tests, and imaging, with biopsy being the gold standard for diagnosis, but not always feasible or necessary.

Key Components of Workup

• Clinical Assessment: A structured clinical assessment, including urine analysis and other basic laboratory tests, should be conducted at each clinical visit to detect new organ involvement 1.
• Laboratory Tests: Anti-neutrophil cytoplasmic antibody (ANCA) testing, including indirect immunofluorescence and ELISA, should be performed in the appropriate clinical context 1.
• Biopsy: A positive biopsy is strongly supportive of vasculitis and should be considered to assist in establishing a new diagnosis and for further evaluation for patients suspected of having relapsing vasculitis, particularly from the kidney 1.
• Imaging: Imaging is recommended as an integral part of the diagnostic evaluation to detect organ involvement and to identify potential biopsy sites, with CT of the chest being more sensitive than conventional radiographs 1.

Special Considerations

• Surrogate Markers: In patients where obtaining or interpreting a biopsy is challenging, surrogate markers such as clinical, laboratory, or imaging findings can support a clinical diagnosis of AAV based on a typical clinical presentation and positive ANCA serology 1.
• Exclusion of Other Conditions: Disorders with a similar clinical appearance, such as infections or malignancies, should be specifically excluded before making a diagnosis of vasculitis 1.

From the Research

Diagnostic Approach to Vasculitis

The diagnostic approach to vasculitis involves a combination of clinical evaluation, laboratory tests, and histopathological examination. According to 2, a detailed history, careful physical examination, and appropriate laboratory tests are needed to determine the type of onset, course of illness, organ systems affected, and extent of involvement.

Key Steps in the Diagnostic Workup

• Determine the level of care the patient needs and order a basic laboratory evaluation if necessary 3
• Determine if the eruption represents vasculitis or vasculopathy, and look for signs such as livedo reticularis or retiform purpura 3
• Rule out secondary causes of vasculitis, such as infection, drug reactions, malignancy, and connective-tissue disorders 3
• Determine the size of the vessel involvement and the organ systems involved to narrow down the differential diagnosis 3

Role of Histopathology

• A histopathologically confirmed biopsy is the gold standard for the diagnosis of vasculitis 4
• The key criteria of morphological vasculitis work-up include vessel size, type of inflammation, and the presence or absence of immune complexes and extravascular inflammatory changes 4
• Histopathology can only provide a definite diagnosis in combination with clinical and serological data 4

Algorithmic Approach to Diagnosis

• A practical and algorithmic approach can be used to assist in the diagnosis of vasculitis, combining clinical and histopathological evaluation with laboratory and radiological evaluation methods 5
• The approach should not be seen as strict rules, but rather as a rational framework for selecting the most appropriate diagnostic approaches 5