Idiopathic Cervical Fibrosis-A New Member of IgG4-Related Sclerosing Diseases: Report of 4 Cases, 1 Complicated by Composite Lymphoma

Idiopathic cervical fibrosis is a rare tumefactive inflammatory-sclerosing lesion involving the soft tissues of the head and neck, and a proportion of patients also have synchronous or metachronous inflammatory fibrosclerosing lesions in other anatomic sites. The latter finding suggests that this entity may represent a member of IgG4-related sclerosing diseases. We report 4 cases to support this postulation. The patients were male adults aged 42 to 89 years, who presented with an infiltrative, firm cervical mass. Two patients also had IgG4-related chronic sclerosing sialadenitis of submandibular gland and lymphadenopathy. Histologically, the cervical soft tissue lesions had ill-defined borders, consisting of coalescent nodular lymphoid aggregates accompanied by a sclerotic stroma. Nerve infiltration, skeletal muscle invasion, and phlebitis were present. There was a significant increase in IgG4(+) plasma cells ( 87 to 327 per high-power field, with IgG4/IgG ratio of 63% to 98%). In the soft tissue lesion of 1 patient, there were expansile foci comprising dense sheets of plasma cells and small lymphoid cells that exhibited kappa light chain restriction and clonal immunoglobulin gene rearrangement, consistent with supervening extranodal marginal zone lymphoma. The adjacent lymph node from the same patient showed Epstein-Barr virus (EBV)-positive classical Hodgkin lymphoma with typical morphology and immunophenotype (CD30(+), CD15(+), PAX5(+)). Thus lymphoma can supervene in the chronic inflammatory background similar to that recently documented for IgG4-related sclerosing disease of the ocular adnexa.