A new injection method for identifying the subpopliteal recess of the knee.

The posterolateral region of the knee has a complex and diverse anatomy. Hydrarthrosis of the knee can potentially communicate with other parts of the joint space. The joint fluid distribution reflects anatomical communications between synovial spaces. To observe the continuity between the knee joint cavity and the surrounding bursa, we devised a dissection method with a new injection agent, an eosin-containing congealed liquid that spreads uniformly over the entire space. The purpose of this study was to perform a detailed examination of the subpopliteal recess (SPR) where a bursa connects to the knee joint capsule. We also reported the advantages of this new injection agent compared with conventional materials (latex and epoxy resin). Twenty-two formalin-fixed cadavers (34 knees), two N-vinyl-pyrrolidone (NVP)-fixed cadavers (4 knees), and two cadavers (3 knees) fixed by Thiel's method were used. After filling the knee joint space and SPR with eosin congealed liquid, the specimens were dissected to investigate the morphology of the SPR. In addition, three different types of injection agents were assessed. The SPR extended distally along the popliteus tendon. The SPR length was 22.64 ± 11.38 mm from the upper end of the lateral tibial condyle to the lower end of the depression. The existence of a fabellofibular ligament made the SPR significantly longer, but abrasion of the femoral articular cartilage did not affect the SPR. Furthermore, the relationship between the popliteus muscle and the SPR was classified into three types (types 1-3). Types 2 and 3 in which the SPR extended to the proximal tibiofibular joint may cause instability of the knee joint. The eosin congealed liquid was highly useful in many aspects, such as fluidity and injection workability. The new dissection method with eosin congealed liquid provides insights into the anatomy of the posterior lateral knee, which are useful for radiological diagnoses and clinical treatments.

Vulvar Adenoid Cystic Carcinoma with Squamous Cell Carcinoma Component.

Adenoid cystic carcinoma (ACC) is a major histological type of salivary gland cancer but an uncommon form of vulvar cancer. Salivary gland ACC occasionally dedifferentiates into high-grade carcinoma, resulting in poor prognoses. The dedifferentiated component is usually a poorly differentiated cribriform or solid carcinoma, whereas squamous cell carcinoma (SCC) is exceptional. Herein, we report the case of a 78-year-old woman with vulvar ACC, including an SCC component. She presented with a vulvar nodule that had been present for 30 years and increased in size over the past few years. Magnetic resonance imaging showed a ball-like mass with high intensity on T1-weighted images and high intensity with non-uniformity on T2-weighted images. Considering the systemic and social conditions, the tumor was maximally resected without lymphadenectomy. Histologically, the tumor was composed of a marginal ACC component with a central SCC component. Stage IB vulvar cancer, which was assumed to originate from the Bartholin's gland, was diagnosed. She has survived over 2 years without additional treatments after the surgery. In this case, we assumed that slowly progressive indolent ACC could be dedifferentiated to high- grade SCC. According to our review of available literature, dedifferentiation of vulvar ACC with a high-grade SCC component has not been specifically documented. Although the nature of dedifferentiated vulvar cancer is unclear, it should be noted that high-grade dedifferentiation can occur in long-lasting vulvar masses.

A histological study of the adult ligamentum arteriosum: Novel findings with application to a patent ductus arteriosus.

The ligamentum arteriosum (LA) is the vestigial fibrous remnant of the ductus arteriosus (DA), a fetal vessel arising from the left dorsal segment of the sixth aortic arch that connects the left pulmonary artery to the aortic arch. Incomplete obliteration of the DA results in a patent ductus arteriosus (PDA), causing the shunting of oxygen-rich blood to recirculate to the lungs, which can lead to pulmonary hypertension. The current study aims to further elucidate the structural characteristics of the LA via histological analysis with data gathered from adult cadaveric specimens. The LA was harvested and histologically observed with Hematoxylin and Eosin, van Gieson, and Masson's trichrome staining. Fibrous and muscle tissues were observed in all 25 specimens. The LA was categorized into three types based on the morphological features of the LA. Type I (vessel-like structure), type II (fibrotic tissue with duct-like structure), and type III (no duct-like structure) were found in 4.0%, 80.0%, and 16.0%, respectively. Finally, the remnant of a valve in the LA was also observed at the junction between the AA and LA. We suggest that this valve be called the "pulmonary-aortic valve." In the majority of the adult LAs, a duct-like structure was still present. These data could better elucidate our understanding of the pathology and etiology of a PDA.

Double Inferior Vena Cava with Major Predominance of the Left Inferior Vena Cava: A Cadaver Case Report.

We encountered a case of a double inferior vena cava with major predominance of the left inferior vena cava during an anatomical dissection course for medical students in 2015. The right inferior vena cava (normal inferior vena cava) was 2.0 mm wide, and the left inferior vena cava was 23.2 mm wide. The fine right inferior vena cava began at the right common iliac vein, ascended along the right side of the abdominal aorta, and then joined the left inferior vena cava at the level of the lower margin of the first lumbar vertebra. The dominant left inferior vena cava started from the left common iliac vein and ascended along the left side of the abdominal aorta. Most patients with a double inferior vena cava are asymptomatic, and these variants are incidentally detected by computed tomography or magnetic resonance imaging. Their presence may have significant implications for surgery, particularly abdominal surgery in patients with paraaortic lymphadenopathy and in those undergoing laparoscopic radical nephrectomy or inferior vena cava filter placement. We herein discuss the embryology of a double inferior vena cava based on detailed anatomical data of the variations of a double inferior vena cava, including those that require clinical attention.

The Key Structure of the Facial Soft Tissue: The Superficial Musculoaponeurotic System.

The superficial musculoaponeurotic system (SMAS) was advocated by Mitz and Peyronie in 1976. The concept of this superficial fascia was established by surgical findings of facelift surgery and is familiar to plastic surgeons and anatomists. However, detailed characteristics of this fascia are still not widely known among head and neck surgeons. Moreover, the SMAS is generally located at the parotid and cheek regions and divides facial fat into superficial and deep layers. The SMAS connects to the superficial temporal fascia cranially and to the platysma caudally. The frontal muscle and the peripheral part of the orbicularis oculi are also in the same plane. The exact expanse of the SMAS in the face is controversial. Some authors claimed that the SMAS exists in the upper lip, whereas others denied the continuity of the SMAS to the superficial temporal fascia in a histological study. There are various other opinions regarding SMAS aside from those mentioned above. The concept of the SMAS is very important for facial soft tissue surgeries because the SMAS is a good surgical landmark to avoid facial nerve injuries. Therefore, this article summarized SMAS from an anatomical point of view.

An Anatomical Dissection Method for Observation of Fibrous Facial Structures.

BACKGROUND: In recent years, structures including the superficial musculoaponeurotic system and retaining ligaments that support the facial soft tissue have been clarified. However, these structures are very difficult to observe in their entirety by the standard gross anatomical procedure (ie, dissection from superficial to deep layers). Furthermore, accurate descriptions of these structures are rare in both anatomical and plastic surgery textbooks. The aim of this study was to clarify the facial fibrous structures in a gross anatomical view. METHODS: The authors' novel method used soft facial tissue and bone. The tissue was fixed in gelatin and sectioned at a thickness of 5 to 10 mm. Each section was placed on a wooden board; the bone was then pinned, and the skin was pulled outward with sutures to hyperextend the soft tissue. Subsequently, the loose connective tissue was torn and fat tissue was removed under a surgical microscope. After the removal of fat tissue, the fibrous facial structures (eg, the superficial musculoaponeurotic system and retaining ligaments) could be observed clearly. RESULTS: The thickness of the sections allowed three-dimensional observation, such that a structure located deep within a section could be clearly observed. The expansion of soft tissue facilitated observation of the facial layer and fibrous structures, and the locations of nerves and vessels. Therefore, the facial layer structure was readily discerned. CONCLUSION: This method is likely to be very useful in the field of plastic surgery because it enabled intuitive identification of facial layers and their characteristics. CLINICAL RELEVANCE STATEMENT: The dissection method developed by the authors reveals the connected morphology of each tissue of the face, thus providing basic data for analyzing soft tissue changes due to aging and gravity. This will be useful for the development of anti-aging medicine.

Gross anatomical study of the subcutaneous structures that create the three-dimensional shape of the buttocks.

The purpose of this study was to clarify the subcutaneous structures involved in the morphology of the gluteal region for clinical application. Thirty-seven formalin-fixed cadavers and one soft-fixed cadaver were used in this study. Gluteal tissue was removed from five formalin-fixed cadavers. A horizontal section and sections parallel to the long axis of the body were made from the excised tissue, and the subcutaneous fat was removed to observe the fibrous structure within the subcutaneous fat. Two formalin-fixed cadavers and one soft-fixed cadaver were used to perform conventional gross anatomical dissection and histological examination. On 30 formalin-fixed cadavers, the thickness of the subcutaneous fat was measured in various areas of the buttocks. The thickness of subcutaneous fat was thicker in the center of the buttocks and thinner on the lateral buttocks. Superficial fascia (SF) was found only in the upper buttock, being indistinct in the lower buttock. In the sacral and coccygeal areas, the dermis was tightly adhered to the bone as a single mass. Fibers arose from around the iliac crest to the SF. On the medial side of the gluteal fold, a strong fiber arose from the sciatic tubercle and inserted into the gluteus maximus and dermis. By identifying the characteristic subcutaneous structures of the gluteal region, we were able to identify the anatomical structures that shape the three-dimensional morphology of the buttocks. These findings may be useful in surgical treatments such as improving the buttock shape.

An Extremely Rare Case of Intestinal Malrotation with an Absent Inferior Vena Cava.

We present a case of intestinal malrotation with an absent inferior vena cava, which was found in a cadaver during a dissection course in our medical school. The intestinal malrotation was Amir-Jahed type 2, with the large intestine on the right side and the small intestine on the left side of the abdominal cavity. The descending colon was fixed on the right side of the posterior abdominal wall and continued into the pelvic cavity from the right side. The cadaver also had a venous system anomaly. The pre-renal segment of the inferior vena cava, which is a section between the renal vein and the hepatic vein, was absent. The inferior vena cava connected to the azygos vein after being joined by bilateral renal veins. The only hepatic segment of the inferior vena cava, which was posterior to the liver and received hepatic veins, penetrated the diaphragm and flowed into the right atrium. To our knowledge, this is the first report of these two anomalies appearing concurrently. We discuss the details of this case and the embryological considerations.

What is a superior labial frenulum? An anatomical and histological study.

Anatomy of the superior labial frenulum (SLF), at first glance, seems to be well established. However, existing studies on the SLF lack description of the incisivus labii superioris (ILS), which cannot be ignored when discussing the SLF. We believe that thorough understanding of the SLF necessitates the anatomical knowledge of the ILS. This study aimed to elucidate the anatomical relationship between the orbicularis oris (OO), ILS, and SLF. A total of 20 formalin fixed human cadaveric specimens were used for gross anatomical and/or histological observation. For histological observation, all specimens were stained with Masson-trichrome. The SLF was a mucosal fold between the gingival mucosa and alveolar mucosa with connective tissue deep to it. The connective tissue attached to the alveolar bone in the junction between the right and left ILS. Skeletal muscle fibers other than orbicularis oris was found in one specimen, which were considered the ILS. During a frenulectomy, removal of the connective tissue bundle is required to prevent recurrence of the high SLF insertion.

Three sublayers in the SMAS: Observations of facial soft tissue using the stretched tissue dissection method focusing on the SMAS.

The characteristics of the superficial musculoaponeurotic system (SMAS), including the morphology of each part and the connection between tissues, remain controversial. The purpose of this study is to clarify the anatomy of the SMAS using our new dissection method. In this study, six hemi-sides of heads from formalin-preserved cadavers were used. Three were used for creating a horizontal section and three were used for creating the section along the axial line perpendicular to the surface of the skin, resulting in a gradual change from the coronal section at the lateral to the sagittal section at the median. The resected head was cut into slices with widths of 7 mm. The stretched tissue dissection method was performed by fixing a tissue slice to a board and pulling the skin outward to stretch the soft tissue. Blunt dissection was then performed under a microscope. The SMAS comprises three layers: superficial, intermediate, and deep. The superficial layer is a thin membrane directly connecting to the septa in the subcutaneous fat. The deep layer is the connective tissue in contact with the sub-SMAS structure. The layer surrounded by the superficial and deep layer of the SMAS is the intermediate layer, containing connective tissue, adipose tissue, and facial muscles. The detailed findings of the SMAS obtained using this method resolve theoretical discrepancies and provide important insight for the field of facial surgery.