Clinical and histological coexistence of inflammatory pseudotumour of the lymph nodes and rheumatoid arthritis.

Inflammatory pseudotumour (IPT) of the lymph nodes is an uncommon, self-limiting, non-neoplastic proliferation of spindle cells, associated with a polymorphous inflammatory cell infiltrate embedded in a collagen-rich stroma and a variable degree of fibrosis, arising in the nodal parenchyma. Its clinical picture is characterised by site-specific signs and the presence, in most cases, of constitutional symptoms. The pathogenesis of IPT is unknown, but it has been interpreted as an aberrant reactive condition of the nodal connective framework, possibly related to viral infections or chronic inflammatory conditions. Its prognosis is usually favourable. We here report the simultaneous onset of seronegative rheumatoid arthritis (RA) and nodal IPT in a 31-year-old woman. Notably, in the nodal biopsy the coexistence of rheumatoid nodules, as well as histological and immunohistochemical features of IPT, was observed. To our knowledge, such an association has not been previously reported and the hypothesis that IPT could represent an unusual epiphenomenon of an RA-related chronic inflammatory response is suggested.