Are rheumatoid nodules really a granulomatous disorder?

Yes. Rheumatoid nodules demonstrate sharply demarcated, palisading granulomas with macrophages surrounding areas of fibrinoid degeneration of collagen deep in the dermis or subcutis. A similar histologic picture can be seen in GA, necrobiosis lipoidica, and rheumatic fever nodules. The differentiation of rheumatoid nodule from deep GA is difficult but possible in most cases. GA demonstrates increased dermal mucin, while rheumatoid nodules demonstrate marked fibrinoid change that is very eosinophilic. Some cases of deep GA cannot be differentiated histologically and require clinical correlation.