Osseous pseudotumor. The sole manifestation of sinus histiocytosis with massive lymphadenopathy.

Sinus histiocytosis with massive lymphadenopathy may involve extra-nodal tissue sites. Skeletal involvement is uncommon and has always been associated with disease in other nonosseous locations. The present case is the first to document sinus histiocytosis with massive lymphadenopathy arising primarily within bone and unaccompanied by disease elsewhere.