Histiocytic lymphoma with sclerosis arising from a nodular lymphoma with a special stromal reaction

Histiocytic lymphoma with sclerosis was found together with a small nodular lymphoma in a cervical lymph node biopsy from a 48-year-old man. Since the cellular origin of this entity is unclear and its ultrastructure has not been described before, we processed formalin-fixed samples for electron microscopy, which revealed three cell types: small lymphocytes with cleaved nuclei, large lymphocytes with vesticular noncleaved nuclei, and mesenchymal stromal cells occasionally bearing desmosomes or hemidesmosomes. In addition, there was an increase of the intercellular connective tissue, which consisted of a mixture of normal and fibrous long spacing collagen fibers. The results indicate that histiocytic lymphoma with sclerosis can evolve from a nodular lymphoma, and that diagnostic information can be obtained by electron microscopy of tissue samples previously fixed in formalin.