Spindle-cell epithelial thymoma. Fine-structural and tumor lymphocyte observations.
A fine-structural study of a spindle-cell epithelial thymoma in a patient with pemphigus and autoimmune hemolytic anemia is presented and compared with the few previously described. Because light-microscopic features suggested hemangiopericytoma, critical fine-structural comparisons between spindle-cell epithelial thymoma and hemangiopericytoma are detailed. Based upon groups of tonofilaments with desmosomal insertions, abundant well-formed desmosomes, negligible numbers of pinocytotic vesicles, and an absence of myofilaments and dense bodies, an epithelial origin for this tumor is proposed. Langerhans' cell granules, a new observation in thymoma, were found in cells of probably histiocytic origin. Tumor lymphocyte studies revealed that more than 95% of cells formed E rosettes, 36% formed EAC rosettes, yet none contained surface immunoglobulin. The significance of these observations is discussed.
Department of Pathology, McGill University and Royal Victoria Hospital, Montreal, Quebec, Canada.
T A
TA
Seemayer
L M
LM
Jerry
L
L
Shapiro
A K
AK
Sullivan
D000744:Anemia, Hemolytic, Autoimmune / Q000150:complications; D003937:Diagnosis, Differential; D005260:Female; D006393:Hemangiopericytoma / Q000473:pathology; D006801:Humans; D008214:Lymphocytes / Q000276:immunology / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000150:complications / Q000276:immunology / Q000648:ultrastructure*; D010392:Pemphigus / Q000150:complications; D013945:Thymoma / Q000150:complications / Q000276:immunology / Q000648:ultrastructure*; D013953:Thymus Neoplasms / Q000150:complications / Q000276:immunology / Q000648:ultrastructure*