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During an educational dissection of a 72-year-old Chinese male cadaver, the hemiazygos vein (HAV) coursing the left side that drains into the persistent left superior vena cava was observed. The HAV was formed at the junction of the 9th to 11th right posterior intercostal veins, right subcostal vein, 5th to 11th left posterior intercostal veins, and left subcostal vein; it then ascended posteriorly to the thoracic aorta. After collecting the accessory hemiazygos vein, it crossed over the aorta and the pedicle of the left lung via the hemiazygos arch, then converged with a communicative branch (vein of Marshall) that emerged from the left brachiocephalic vein to form the persistent left superior vena cava and entered the pericardium at the level of the sixth thoracic vertebra. Upon opening the pericardium of our cadaver, the persistent left superior vena cava was found to drain directly into the significantly dilated coronary sinus at the level of the eighth thoracic vertebra. The azygos vein was formed by the union of the first to eighth right posterior intercostal veins and appeared to be finer and shorter than the HAV. The persistent left superior vena cava might be the result of incomplete degeneration of the left posterior cardinal vein. Knowledge of such variations could be of great value to surgeons placing peripherally inserted central catheters because incorrect placement of the azygos venous system can be detrimental to the patient. In addition, during heart surgery, awareness of such variations may prevent major complications, such as hemorrhage or damage to vascular structures, and possibly also provide new insights and perspectives to cardiovascular surgeries.

Subjects with persistent left superior vena cava were classified on the basis of the presence and thickness of both superior venae cavae, the anastomotic ramus between the superior venae cavae (anastomotic ramus), and the presence of both azygos veins. Among subjects with persistent left superior vena cava, the percentage of those with weak development of the anastomotic ramus (41.5 %) or absence of an anastomotic ramus (35.8 %) was 77.3 %. In addition, 54.7 % of subjects had a left azygos vein. However, 88.7 % of subjects had a right azygos vein. In this classification, the most frequently observed types included the presence of both superior venae cavae, an anastomotic ramus, and both azygos veins (20.8 %). During student dissection practice sessions performed on 337 cadavers that were carried out from 2002 through 2010, a subject having a left superior vena cava (in 2002) and a subject having both superior venae cavae (in 2003) were detected. The former case was reported previously. The latter case is reported in this paper. The incidence of persistent left superior vena cava was 0.59 % (2/337 cadavers).

A left inferior vena cava was found in the cadaver of an 88-year-old Japanese man during a student dissection course at Kumamoto University School of Medicine. The right common iliac vein ascended obliquely toward the left behind the right common iliac artery and united with the left common iliac vein to form the inferior vena cava in front of the fifth lumbar vertebral body behind the left common iliac artery. The inferior vena cava ascended on the left side to the aorta, and after the left renal vein joined to it at the level of the third lumbar vertebral body, it turned obliquely to the right and crossed superficially to the aorta. At the right side of the aorta, the common stem of the third lumbar vein and the posterior renal vein was joined to the oblique part. The inferior vena cava then ascended, receiving the right renal vein as it would normally. The inferior vena cava is thought to develop symmetrically but this left inferior vena cava shows a persistence of the left channel of the infrarenal part, which normally disappears. Although the common stem of the veins that joined to the oblique part on the right side did not continue to the right common iliac vein, gross anatomical findings suggested it to be the remnant of the right inferior vena cava.

After the authors' previous report an additional case of partial anomalous pulmonary venous return was encountered during dissection practice for medical students. In an 87-year-old Japanese male cadaver, the anomalous vein from the right upper lobe drained into the superior vena cava at a point just below the entrance of the azygos vein. This case is similar to the first case in the authors' previous report, but the anomalous vein was recognized before dissection of the lung began. Therefore, findings were more precisely observed. The anomalous pulmonary vein was 16 mm in diameter and had three branches, which drained the regions of the apex, the anterior segment and a part of the posterior segment of the right upper lobe. The other veins from the right lung gathered into two pulmonary veins, measuring 21 mm and 18 mm in diameter, respectively, and returned to the left atrium as usual. It is noteworthy that the anomalous vein received the bronchial vein from the right upper lobe bronchus. The azygos vein also received the bronchial veins from the lower part of the trachea and from the right middle and lower lobe bronchi. The theory that the bronchial vein plays an important role in the occurrence of the anomalous pulmonary drainage is further supported by this finding.

The azygos lobe is a rare anomaly in broncho-pulmonary segmentation due to an unusual course of the azygos vein. Its radiological aspects are well known but there are few anatomical reports about its bronchial and vascular components. The authors describe the characteristic features in a particular case of the azygos lobe observed in the right lung after studying a fresh specimen and doing a casting of said specimen. This azygos lobe was in a position medial to the right upper lobe and above the hilum. It had the shape of an egg and was 5 cm high, 4 cm wide and 2 cm thick. The azygos fissure was of a vertical form. The lobe was ventilated by the posterior branch of the apical segmental bronchus (B1a). This latter was accompanied by two apical sub-segmental arteries (A1ai, A1aii) and the apical intersubsegmental vein (V1a). The new findings were that: first, the azygos lobe bronchus supplied a part of the right upper lobe; second, the passage of the azygos vein deformed the bronchus of the right upper lobe, and not that of the azygos lobe. This means that it was the right upper lobe, rather than the azygos lobe that was predisposed to the pathology. So, in excising this type of azygos lobe, particular precautions have to be taken to spare the bronchus of the azygos lobe that supplies the right upper lobe.

During an ordinary dissection by medical students at Nara Medical University in 1998, a case of anomalous inferior vena cava with azygos continuation was found in a cadaver of a 91-year-old Japanese man. The left and right inferior venae cavae were present and were joined at the height of the first lumbar vertebra. The joined inferior vena cava continued the azygos vein and the azygos vein entered the superior vena cava at the height of the fifth thoracic vertebra. Furthermore, the heart was normal.

Two examples of partial anomalous drainage of the pulmonary vein were detected at dissection. The first case was found in a 70-year-old female Japanese. An aberrant vein, approximately 6 mm in diameter, that derived from the upper lobe of the right lung was observed to drain into the superior vena cava at a point just below the entrance of the azygos vein. The other veins from the right lung gathered into two pulmonary veins and returned into the left atrium as usual. In the second case, which was found in an 80-year-old female Japanese, a connecting vein, approximately 8 mm in diameter, was found between the left superior pulmonary vein and the left brachiocephalic vein. In this case, although the direction of the blood flow within the connecting vein was not certain, it is probable that the blood passed from the pulmonary vein into the brachiocephalic vein, judging from the increase in the width of the latter vein. No other anomalies were found in the cardiovascular systems. At the occurrence of the anomalous drainage of the pulmonary veins in both cases, we suspected the role of the bronchial vein to be a communicating and boundary vein between the pulmonary and systemic circulations. The developmental background of these anomalies is also considered.