Solitary crystal-storing histiocytosis of the tongue in a patient with rheumatoid arthritis and polyclonal hypergammaglobulinemia

A 73-year-old woman with a long history of rheumatoid arthritis and polyclonal hypergammaglobulinemia developed a solitary mass in the tongue, which on morphologic and immunohistochemical analyses was consistent with crystal-storing histiocytosis, a rare condition commonly described in association with clonal lymphoplasmacytic disorders. The lesion consisted of a localized collection of histiocytes filled with numerous eosinophilic crystals immunoreactive for both κ and λ light chain and γ heavy chain antibodies. Mature lymphocytes and plasma cells were present both throughout and around the lesion. Since a clonal lymphoplasmacytic neoplasm was ruled out by clinical and immunohistochemical studies, we consider that, in this case, crystal-storing histiocytosis was consequent to polyclonal hypergammaglobulinemia and suggest that this rare histiocytosis is not specific to lymphoplasmacytic neoplasms, but may represent a reaction to high values of normal (or abnormal) immunoglobulins.