Page 188 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

164 Lindsay Lally and Stephen A. Paget

bacterial strain in the temporal arteries of subjects with GCA. Two other pathogens,
Treponema pallidum, the spirochete pathogen of tertiary syphilis, and Mycobacterium
tuberculosis (TB), both contribute to the development of aortitis and LVV, with histologically
evident-evident chronic granulomatous in endemic areas where the prevalence of TAK is
high.

Prescription Medication

There is an ever-growing list of medications associated with hypersensitivity vasculitis.
The clinical presentation is usually self-limited and resolves once the offending agent has
been identified and removed. Some prescription drugs, such as hydralazine and
propylthiouracil are associated with ANCA-seropositivity but not vasculitis. An important
distinction in the diagnosis of drug-induced AAV is that unlike idiopathic AAV, those with
drug-induced ANCA-seropositivity often have antibodies against more than one antigen [11].

Substance Abuse

A history of intra-nasal cocaine use in a patient with suspected vasculitis may be a clue to
the cause of cocaine-induced midline destructive lesions (CIMDL) of the midline sinuses that
resembles the lesions of GPA. Further complicating the distinction between CIMDL and
AAV is the presence of ANCA-seropositivity. Cocaine-induced CIMDL can be associated
with p-ANCA, c-ANCA or both. The most common autoantibody in CIMDL, occurring in
84% of patients in one study, was atypical p-ANCA directed against human neutrophil
elastase (HNE) [12]. Anti-HNE antibodies are not found in patients with GPA. Requesting
specific ANCA serology by the immunofluorescence technique (IFT), and not just the ANCA
pattern, avoids misdiagnosis between CIMDL and sino-nasal GPA.

Procoagulopathy

Prothrombotic disorders may mimic systemic vasculitis, while manifestations of anti-
phospholipid syndrome (APS) can in turn overlap with systemic vasculitis. Affected patients
with catastrophic APS can present with pulmonary-renal syndrome and unlike those with
SVV, such patients with APS and alveolar hemorrhage require anti-coagulation. The non-
criterion manifestations of APS-like skin ulcers and emboli from verrucous valvular disease
can appear grossly similar to vasculitic lesions. Skin biopsy that shows in situ thrombi instead
of vascular inflammation can distinguish the two entities. One other clue to the diagnosis of
APS is the presence of thrombocytopenia instead of thrombocytosis more often encountered
in systemic vasculitis. Thrombotic thrombocytopenic purpura (TTP) and the hemolytic
uremic syndrome (HUS) which present with fever, purpuric rash, acute renal failure, and
neurologic involvement is also noted in SVV and accompanied by hemolytic anemia and
schistocytosis on peripheral blood smears. Thrombotic microangiopathy is not generally
encountered in primary vasculitides.

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