Positive c-anca 1:640 with negative pr3

What autoimmune disorders can have strongly positive c-anca but have negative pr3. I have vasculitis in my left eye and I had an abnormal chest xray. Ct guided biopsy was negative for cancer. Dr Foster (as featured on Mystery Diagnosis TLC network) tentatively thought it was sarchoid but my pulmonologist says it isn't. All my other tests were negative except for a slightly elevated ana of 1:80. I have so far been less than confident in the diagnoses. I am of the understanding that it is rare to have a highly positive c-anca but be negative for pr3. Can anyone offer their input as to what direction I should go next?

[Red_Star]

Info from Brighton & Sussex Pathology:

In general in the context of small vessel vasculitis:

C-ANCA is associated with anti-PR3 antibodies and is found in Wegener’s Granulomatosis, and Churg-Strauss Syndrome.

P-ANCA is associated with anti-MPO antibodies and is found in Microscopic Polyangiitis, Crescentic Glomerulonephritis and Churg-Strauss Syndrome.

But this is variable and one may have C-ANCA with anti-MPO and P-ANCA with anti-PR3, or combinations of antibodies.

A positive ANCA with negative anti-MPO and PR3 may be found in a variety of conditions including autoimmune hepatitis, sclerosing cholangitis, ulcerative colitis, SLE, RA, malignancy and chronic infections. ANCA testing is not warranted for these clinical conditions.

[tom73]

My doctor wanted to start me on methotrexate but I don't like the thought of starting that drug without some sort of definitive diagnosis.