Paranuclear microfilaments in multiple myeloma associated with the presence of free light chains

Two cases of multiple myeloma are reported showing striking arrays of paranuclear microfilaments confirming a previous single case report done on autopsy material. Both cases showed free light chains in the urine. In one case, free light chains were in the serum, and there was some evidence of polymer formation. Although this suggests that the microfilaments are polymerized light chains, amyloid strains were negative. Whatever their origin, the structures are clearly abnormal and may serve as a neoplastic marker.