RESULTS: There were seven men and six women, with a median age of 60 years (range, 33-79 years). CSH was generalized in one patient (8%) and localized in 12 (92%) patients, involving various sites. CSH was associated with a low-grade B-cell lymphoma with plasmacytoid differentiation or a plasma cell neoplasm in all cases. In 10 (77%) cases, CSH represented >50% of the neoplastic infiltrate. According to immunohistochemical studies, histiocytes were positive for monotypic kappa in 5 (50%) cases, and for monotypic lambda in 4 (40%) cases; in 1 (10%) case, the results were equivocal. MS analysis of the histiocyte contents in all three tested cases showed a predominance of variable-region fragments of Ig light and/or heavy chains.
CONCLUSIONS: CSH is frequently associated with an underlying lymphoplasmacytic neoplasm. MS findings suggest that Ig alterations and/or possibly defects in the ability of histiocytes to process Ig play a role in pathogenesis.