Multilaminar endoplasmic reticulum and abnormal mitosis in Hodgkin tumor cells

A multilaminar alteration of endoplasmic reticulum (ER) has been observed in tumor cells of eight patients with Hodgkin's disease and a patient with histiocytic lymphoma. These multilaminar structures are more numerous in dividing cells and thus appear to arise primarily during mitosis. The stacked membranes in the multilaminar structures possibly result from abnormal sticking of organelle membranes, as evidenced in this study of adherence of ER to other elements of ER, nuclear envelope, mitochondria, or lipid droplets. Multilaminar ER was identified in all mitotic tumor cells, a rare mitotic plasma cell, and numerous interphase Hodgkin cells. The paucity of multilaminar ER in normal mitotic cells and its virtual absence for normal interphase cells suggest that this structure represents a pathological alteration in tumor cells from patients with Hodgkin's disease and histiocytic lymphoma. The multilaminar defect of ER is associated with other atypical features of ER in Hodgkin tumor cells, including the excessive length and curving of ER profiles, the collapse of the ER cisternae, and the overall sparsity of this organelle. Other abnormalities observed in mitotic Hodgkin tumor cells include the presence of disorganized microtubules, large cytoplasmic vacuoles, and abnormally clumped chromosomal material and the persistence throughout mitosis of bodies suggestive of nucleoli and of the nuclear bodies of interphase cells.