Laboratory Studies
The erythrocyte sedimentation rate is commonly elevated in patients with Vilanova disease.
The antistreptolysin O titer should be checked because it is elevated in some patients.
The physician should perform a tuberculin skin test because other diseases in the differential diagnosis can have tuberculous etiologies.
Serum rheumatoid factor levels have been elevated in some patients, although the reason for this is not known.
A CBC count can be performed to rule out infection, especially if the patient has described a sore throat or a fever.
An antinuclear antibody or anti-dsDNA antibody test can be ordered to help rule out lupus panniculitis.
An alpha1-antitrypsin level can be ordered to help rule out deficiency-induced panniculitis.
Anti-DNAse B titers also may be elevated, as they are often elevated in various forms of panniculitis.
Several cases have been reported of Vilanova disease associated with thyroid disease. Thyrotropin and free T4 levels should also be checked.
Imaging Studies
A chest radiograph should be obtained to rule out sarcoidosis and tuberculosis.
Histologic Findings
Subacute nodular migratory panniculitis is histologically characterized by granulation tissue–like capillary proliferation and septal widening secondary to granulomas and fibrosis. A mild lymphocytic and giant cell inflammation is observed, often lining the walls of the septa or adjacent deep dermis. [15] Eosinophils and neutrophils may also be observed. The endothelial cells of the small vessels proliferate and can fill the entire lumen. The capillaries can take on a coiled, swollen appearance. Little to no vasculitis or phlebitis is present. The septa of the subcutaneous tissue exhibit granulomatous changes and notable changes in collagen fibers. [16]
In contrast, chronic erythema nodosum exhibits small vessel vasculitis and only mild septal change. Disease may extend to the adjacent fat lobules, and the inflammation often extends up to the deep dermis. Septal fibrosis is not present in chronic erythema nodosum.
