RESUMEN
OBJECTIVE: To describe a cytomorphologic criterion that may help improve diagnostic safety in morphologic differentiation of non-Hodgkin's lymphoma (NHL) from carcinoma or sarcoma and investigate the significance of this cytomorphologic phenomenon. STUDY DESIGN: Eighty-two smears of NHL, carcinoma and sarcoma smears were examined. Forty-five smears were from patients with carcinoma and 35 from patients with NHL. The remaining 2 smears were from patients with sarcoma. RESULTS: In 40 of 46 smears of carcinoma or sarcoma the nuclear membrane was assessed as "open" by the observer. In 6 smears the membrane was assessed as "closed. " In 30 of 35 smears with histologically confirmed NHL, the membrane was estimated as being closed. In the remaining 5 smears it was assessed as open. The sensitivity of evaluating the parameter as open or closed membrane was 87% and the specificity was 86%. The negative predictive value was 89%, and the positive predictive value was 83%. CONCLUSION: We suggest that the presence of an open or closed nuclear membrane may be helpful in differentiation of malignant lymphoma from carcinoma or sarcoma and may help improve diagnostic safety in daily practice.