Spindle cell tumor of lymph node of probable reticulum cell origin associated with multiclonal gammopathy

We describe a case of a 48 year old man who presented repeatedly with a neck lymph node tumor. The tumor grew insidiously over 11 years and the patient died at the age of 58 with the generalization of the tumor into the right cervical, paratracheal lymph nodes and spleen. The tumor was composed of spindle shaped cells with occasional intranuclear cytoplasmic pseudoinclusion. At the ultrastructural level the tumor revealed membrane bound crystalline inclusions, which were locally in direct contact with both the nuclear envelope and confronting cisternae of the endoplasmic reticulum. The tumor was associated with multiclonal gammopathy composed of two subsets of IgG/lambda and one subset of IgA/lambda positive paraprotein produced by lymphoid cells surrounding the tumor. We diagnosed the tumor as "spindle cell tumor of lymph node of probable reticulum cell origin associated with multiclonal gammopathy" and consider the lymphoid tissue producing the paraprotein to be reactive.