Development and Migration of Megakaryocyte during Hepatic Hemopoiesis in Human Fetuses / 대한해부학회지

Liver tissuses obtained from 5 human fetuses between 11 weeks and 23 weeks of gestation during the high activity of hepatic hemopoiesis were observed with transmission electron microscope using continuous series of thin sections. The objective of present study was to evaluate ultrastructures of megakaryopoietic cells, the migration of extravascular megakaryocyte into the sinusoidal lumen and the relevence between a migrated megakaryocyte and a Kupffer cell. Immature megakaryocytes were usually observed between growing hepatic laminae and within hepatic sinusoids. A megakaryoblast contained numerous polyribosomes, rather large mitochondria, short tubular elements of rough endoplasmic reticulum and small granules. Moreover, demarcation tubules and a few small specific granules were observed in immature megakaryocytes. The nucleus was mononuclear but frequently indented. With maturation, the nuclei were multilobulated. In the cytoplasm, in contrast to the decrease in polyribosomes and rough endoplasmic reticulum, the numerous specific granules and well -developed demarcation membrane system were predominant. Thereafter cytoplasmic zonation was observed clearly in maturing and mature megakaryocytes. Some megakaryocytes passed through the sinusoidal lining epithelium and into the hepatic sinusoids. The cell to cell interaction was often found as adhesion between migrated megakaryocyte and Kupffer cell, and erythroblasts within megakaryocyte (emperipolesis). These results suggest that intravascular megakaryopoiesis in addition to extravascular megakaryopoiesis occurs to produce platelet during the human fetal liver.

Clinical Analysis for Lymph Node Metastasis as a Guide to Modified Surgery for Early Gastric Cancer

The authors have analyzed the clinicopathologic data of 855 patients with early gastric cancer (EGC) who underwent D2 lymph node dissection during the 7-year period between January 1990 and December 1996 in order to evaluate the factors influencing lymph node metastasis and to establish the clinical indications and guidelines for modified surgery in EGC patients. The overall rate of lymph node metastasis was 13.5% (115/855). There was a significant statistical difference for lymph node metastasis between men (67/575, 11.7%) and women (48/280, 17.1%)(p<0.05). In mucosal cancer, the rate of lymph node metastasis was 4.7% (20/427), and in submucosal cancer, it was 22.2% (95/428), which is a significant difference between the two groups. There was also a significant difference for lymph node metastasis between the elevated types (EGC type I and IIa) and the depressed types (type IIb, IIc, and III), 8.4% (13/154) and 14.6% (102/701), respectively (p=0.05). There were only one lymph node positive case (1/82, 1.2%) among the elevated mucosal cancers. Smaller tumors((10 mm) showed a significantly lower incidence of lymph node metastasis than larger tumors (11 mm)(p<0.01); 4 cases invoving tumors of less than 11 mm had lymph node metastasis(2 mucosal and 2 submucosal lesions). Differentiated mucosal carcinomas showed a significantly lower incidence of lymph node metastasis than undifferentiated carcinomas (0.9% vs 8.5%, p<0.001), whereas there was no significant difference between differentiated and undifferentiated submucosal cancers. There were 14 cases of EGC with metastasis in the secondary lymph node group (N2) consisting of 5 men and 9 women, with a mean age of 53 years. Among them, the 7 cases under the age of 50 were all female patients. For thses 14 case, the average tumor size was 34 mm (15~90 mm), and the majority of were depressed types (11 cases) and undifferentiated type (12 cases). These results suggest that modified surgery is indicated as an optimal treatment option for mucosal cancer with elevated and/or differentiated type tumors, on the basis of not only radicality but also postoperative quality of life.

Treatment of Obstructive Colorectal Cancer

The occurrence of the colonic obstruction secondary to colorectal carcinoma (CRC) has been reported in 7~30% of the CRC patients. It is generally believed that obstructive CRC is associated with a poor prognosis with respect to operative mortality and five-year survival. A series of 1064 cases of the CRC treated surgically at Asan Medical Center from June 1989 to December 1996 has been analyzed to compare clinicopathological findings between obstructive and non-obstructive CRC and to evaluate surgical treatment options in obstructive CRC. Complete obstruction was present in 49 cases (4.6%). There were no differences between obstructive and non-obstructive CRC in tumor location, size, Dukes' stage, and differentiation. In forty-nine obstructive CRC cases, primary resections were performed in 29 cases after peri-operative bowel decompression. In this group, right colon cancer was more prevalent than staged operation group (45% vs. 5%, P<0.05) and hospital stay was significantly short (16 days vs. 38 days, P<0.05). Postoperative complication rate was higher in staged operation group (65% vs. 28%, P=0.01). It may be due to stoma related wound complication. In obstructive left colon cancer, there was a significant difference in complication rate between primary resection and staged operation (P<0.05). Overall 5-year survival rate were 66% and 53% in non-obstructive and obstructive group, respectively. Survival rate according to the Dukes' B and C stages did not show statistical differences, either. Conclusively, primary resection is preferred to the obstructive CRC when supportive care, preoperative bowel decompression, and intraoperative colonic irrigation were performed adequately.

A Case of the Pancreatic Pseudocyst due to Metastatic Malignant Melanoma / 대한암학회지

Malignant melanoma constitutes approximately 1% of all cancer (1,2). As the biologic behavior seems to be unpredictable, variation in the metastatic spread are not infrequently met. The common sites of metastasis are lymph nodes, lung, liver, brain, bone, heart, adrenal glands, and gastrointestinal tract in descending order (2). However multiple organ involvement is a common feature at the advanced stage. A 38-year-old male had developed pancreatic pseudocyst during the course of malignant melanoma at right sole. It was proven to be from matastatic malignant melanoma.

Four Cases of Rectal Melanoma

Although anal canal is the most common site for the development of malignant melanoma in the alimentary tract, it is extremely rare and melanoma can occur primarily at lower rectum. Anorectal melanoma constitutes 0.4% to 0.8% of colorectal malignancies and less than 2% of melanomas. The prognosis may depend on the extent of disease and depth of invasion. It generally seems to be very poor in spite of aggressive treatment. We have treated four patients of rectal melanomas out of 1,477 cases of all colorectal cancer between September, 1989 and January, 1997 ; a 39-year-old female with the intermittent blood-tinged stool, a 51-year-old male with hematochezia, a 59-year-old male with anal bleeding and a 65-year-old female with anal bleeding. They were treated by abdominoperineal resection with pelvic lymph node dissection and were confirmed histologically rectal melanomas.