Does a Subset of Localized Chronic Fibrosing Vasculitis Represent Cutaneous Manifestation of IgG4-Related Disease/a Histologic Pattern of IgG4-Related Skin Disease? A Reappraisal of an Enigmatic Pathologic Entity.

Localized chronic fibrosing vasculitis (LCFV) is a rare cutaneous fibroinflammatory and vasculitic process of poorly defined etiology. Furthermore, controversy remains as to whether LCFV represents a primary pathologic process or a histologic pattern. The current case documents a 52-year-old male patient with a scrotal mass and clinical history of a retroperitoneal mass as well as a previously resected tumor of the right submandibular salivary gland displaying morphologic features of eosinophilic angiocentric fibrosis. Histologic examination of the resected scrotal mass revealed a tumefactive lesion characterized by focally storiform fibrosis, obliterative phlebitis, tissue infiltration by IgG4-positive plasma cells, and leukocytoclastic vasculitis. Apart from the leukocytoclastic vasculitis, the scrotal lesion demonstrated characteristic morphologic features of an IgG4-related disease (IgG4-RD). In recognition of the combined histologic findings of both LCFV and IgG4-RD in the scrotal mass, it was postulated that a subset of LCFV cases might represent cutaneous manifestations of IgG4-RD or a new histologic pattern of IgG4-related skin disease (IgG4-RSD). The literature analysis of previously reported LCFV cases appeared to lend credence to this hypothesis. Pathologists should be aware of this new histologic pattern of IgG4-RSD as judicious consideration for additional studies might potentially detect an unexpected systemic IgG4-RD in the patient, particularly in cases of LCFV displaying storiform fibrosis associated with plasma cell infiltrate.