Fusion Plane Research Articles

A Case of Basal Cell Carcinoma Arising in Bilateral Mastoidectomy Scars

A Case of Basal Cell Carcinoma Arising in Bilateral Mastoidectomy Scars

Frontal branch of the facial nerve: Galeal temporal relationship

Risks to the frontal branch of the facial nerve, especially at the juncture of the zygomatic arch, have been well studied in connection with aesthetic procedures. The use of bicoronal incisions led to the observation that there is a second area in which injury to the frontal branch of the facial nerve is at risk: the transition plane between the area over the temporalis muscle and the pericranial region. A study was conducted to map out the frontal branch of the facial nerve as it passes through the dense galeal temporal fascia, because this is a zone of potential injury. Ten fresh frozen cadaver halves were dissected by use of a standard surgical bicoronal approach with surgical instrumentation and loupe magnification x 2.5. In the area of interest, which included the region overlying the zygomatic arch, as well as the galeal frontalis fusion point, the nerve was found to be deep and within the fusion point. The nerve was cephalad to the sentinel vein in each instance, and the tissue was freely dissected medial and lateral to the fusion point of the galea and the temporal fascia. The fusion plane was dense and in a direct line in the vertical direction with the loose areolar plane on either side. The dense tissue within the galeal temporal region needs to be approached with caution, avoiding electrocautery and using sharp dissection. The cadaver study demonstrates the close proximity of the nerve in the deeper portion of the elevated superficial flap.

Correlation of Embryonic Fusion Planes with the Anatomical Distribution of Basal Cell Carcinoma

Correlation of Embryonic Fusion Planes with the Anatomical Distribution of Basal Cell Carcinoma

Correlation of Embryonic Fusion Planes with the Anatomical Distribution of Basal Cell Carcinoma

The clinical relevance of the anatomic distribution of basal cell carcinoma is not completely understood. Embryonic fusion planes--the regions of mesenchymal migration and fusion of the five primordial facial processes during the 5th to 10th weeks of human development--have been implicated in the pathogenesis of basal cell carcinoma. This study sought to examine the predilection of midfacial basal cell carcinoma for cutaneous anatomical sites correlated to embryonic fusion planes. Using archived digital images and a detailed anatomic diagram, cases of basal cell carcinoma were coded according to their specific location and were aggregated into two anatomic domains according to their correlation to embryonic fusion planes. The relative tumor densities were calculated. Of the 1,457 cases examined, 859 were located in the midface. Thirty-five percent of the midfacial lesions were located on the domain correlated to embryonic fusion planes, which represented 11.3% of the total surface area of the midface. The relative tumor density of lesions in the fusion plane domain was 3.06 compared to 0.74 for the remaining lesions (p< .001). Although there is no consensus about the importance of anatomic location in the pathogenesis of basal cell carcinoma, these data indicate that, after adjusting for surface area, basal cell carcinoma was more than four times more likely to occur on an embryonic fusion plane than on other regions of the midface. These data support the possibility of an embryologic role for the pathogenesis of basal cell carcinoma.

Aggressive Basal Cell Carcinoma with Invasion of the Parotid Gland, Facial Nerve, and Temporal Bone

Aggressive variants of basal cell carcinoma (BCC), such as infiltrating, morpheaform, and basosquamous types, are associated with invasion of underlying tissues and are often difficult to treat.1 BCCs located in embryonic fusion planes, such as the periauricular region, are thought to exhibit deep extension and, subsequently, high recurrence rates, although this theory has been challenged and remains controversial.2-4 Despite the known features of aggressive BCC, parotid gland invasion and temporal bone and facial nerve involvement are rarely reported occurrences. We describe two patients with morpheaform BCC in the periauricular region demonstrating direct invasion of the parotid gland and concomitant facial nerve involvement. These patients require complex surgical management, as highlighted in this report.

Aleurone Cell Identity Is Suppressed following Connation in Maize Kernels

Expression of the cytokinin-synthesizing isopentenyl transferase enzyme under the control of the Arabidopsis (Arabidopsis thaliana) SAG12 senescence-inducible promoter reverses the normal abortion of the lower floret from a maize (Zea mays) spikelet. Following pollination, the upper and lower floret pistils fuse, producing a connated kernel with two genetically distinct embryos and the endosperms fused along their abgerminal face. Therefore, ectopic synthesis of cytokinin was used to position two independent endosperms within a connated kernel to determine how the fused endosperm would affect the development of the two aleurone layers along the fusion plane. Examination of the connated kernel revealed that aleurone cells were present for only a short distance along the fusion plane whereas starchy endosperm cells were present along most of the remainder of the fusion plane, suggesting that aleurone development is suppressed when positioned between independent starchy endosperms. Sporadic aleurone cells along the fusion plane were observed and may have arisen from late or imperfect fusion of the endosperms of the connated kernel, supporting the observation that a peripheral position at the surface of the endosperm and not proximity to maternal tissues such as the testa and pericarp are important for aleurone development. Aleurone mosaicism was observed in the crown region of nonconnated SAG12-isopentenyl transferase kernels, suggesting that cytokinin can also affect aleurone development.

Vocal Process Avulsion

Vocal process avulsion is a rare complication of intubation or external laryngeal trauma that can cause significant dysphonia. The vocal process develops independently from the body of the arytenoid cartilage, which results in a fusion plane that is vulnerable to trauma. The findings of vocal process avulsion may be subtle, and the relationship of the vocal process to the body of the arytenoid cartilage must be examined closely. Stroboscopy is critical in the evaluation. We describe three cases of vocal process avulsion encountered by the senior author (R.T.S.) over the last 5 years and discuss our approaches to evaluation and treatment. All cases were repaired endoscopically. However, we used three different techniques. These include chemical tenotomy with botulinum toxin, closed reduction with fat injection, and open reduction via cordotomy.

Risk factors for incomplete excision of squamous cell carcinomas

Objective: The aim of this study was to identify risk factors for incomplete excision of squamous cell carcinomas (SCCs). Patients and methods: A cross‐sectional study of 369 patients who underwent a primary excision of SCCs was performed within an outpatient and a hospital plastic surgery department setting. Results: Incomplete excision occurred in 25 of 369 primary excisions of SCC (6.8%). Location of the tumors on the forehead, temples, peri‐auricular region, ears, cheeks, nose, lips or neck was significantly associated with incomplete excision of the tumors. In particular, high incomplete excision proportions were observed for tumors located on the ears (16.7%), neck (16.7%), temples (11.1%), nose (10.8%) or lips (7.1%). Incomplete excision of SCC was associated with the setting of the operation in the hospital as compared to ambulatory settings (p = 0.046) and was inversely associated with the specimen thickness (p = 0.002). There was no statistically significant association between incomplete excision of SCC and gender, age, clinical appearance of the lesion (suspected SCC vs other diagnoses), differentiation pattern, diameter of the tumor, length or width of the excised specimen, solar changes or ulceration. Conclusion: We recommend that in patients with SCCs located in the forehead, temples, periauricular region, ears, cheeks, nose, lips or neck surgeons should commence particular surgical measures to avoid inadequate excisions of the tumors. In particular, surgeons should use wider excisional margins in tumors located in the embryonic fusion planes (e.g. eyelids and naso‐labial folds).

Correlation of embryonic fusion planes with the anatomical distribution of basal cell carcinoma

Correlation of embryonic fusion planes with the anatomical distribution of basal cell carcinoma

Measurements and Monte Carlo simulation of grain growth in the heat-affected zone of Ti–6Al–4V welds

Grain size and topological class distributions in the heat-affected zone (HAZ) of gas tungsten arc welded Ti–6Al–4V alloy were measured for various heat inputs in the range of 0.55–4.33 MJ m −1. The evolution of grain structure and topological class distributions were also calculated using a three-dimensional Monte Carlo model utilizing thermal cycles computed from a well tested numerical heat transfer and fluid flow model. Both the experimental data and the calculated results showed that the average prior-β grain size near the fusion plane was about four to twelve times larger than the average grain size in the base plate, depending on the heat input. At locations equidistant from the fusion plane, the grains were larger in the mid-section vertical symmetry plane as compared to those at the top surface due to local variations of the thermal cycles. The normalized grain size distributions were unaffected by the local differences in the thermal cycles. It is demonstrated that the presence of a spatial gradient of temperature in the HAZ significantly impeded grain growth due to thermal pinning effect. Furthermore, the steep temperature gradients near the fusion plane did not introduce any significant texture in the grains. Both the experimental data and the calculated results indicated that the grains in the HAZ of the Ti–6Al–4V alloy were significantly smaller than the grains in the commercially pure titanium for identical welding conditions.

The Nonrandom Distribution of Facial Hemangiomas

Source: Waner M, North PE, Scherer KA, et al. The nonrandom distribution of facial hemangiomas. Arch Dermatol. 2003;139:869–875.Infantile hemangiomas frequently develop on the face and the majority of cases resolve without significant morbidity. Lesions which localize around certain anatomic locations, such as the eye and the beard, may be associated with regional complications such as amblyopia and airway involvement, respectively. 1 Posterior fossa malformations have been linked to large facial hemangiomas, as well as arterial, cardiac, and eye anomalies, and midline sternal and supraumbilical defects, known collectively as PHACES syndrome.2 Occasionally, facial hemangiomas may ulcerate with resultant scarring. Why hemangiomas appear where they do and which hemangiomas develop complications has remained a mystery.In this study, investigators retrospectively reviewed the records of 205 children with 232 facial hemangiomas who had been referred to the Vascular Anomalies Clinic of the Arkansas Children’s Hospital in Little Rock. The diagnosis of hemangioma was made on clinical grounds with histologic confirmation in a minority of cases. Attention was paid to where lesions appeared on the face and whether complications developed. The lesions were segregated on the basis of anatomic extent—as either focal or diffuse (segmental)—and then mapped on a standardized template to evaluate patterns of distribution.The majority of hemangiomas (177/232 or 76%) were classified as focal, while the remaining were diffuse. The distribution of focal lesions localized to one of 22 clusters which each corresponded to margins of embryonic fusion planes known as facial placodes (see Figure). Most focal lesions occurred in the central face (60%). Diffuse hemangiomas were localized within areas marked by embryonal facial placodes of the frontonasal, maxillary, and mandibular areas or segments. Diffuse lesions were also far more commonly complicated by ulceration (51%) than focal lesions (17%). Systemic complications, such as subglottic airway involvement, were associated with diffuse hemangiomas within the mandibular distribution (38% of mandibular lesions) rather than focal hemangiomas (0%), even when the latter appeared in a beard distribution.This provocative series suggests that facial hemangiomas have a nonrandom distribution. Diffuse lesions, which distribute along and within segments defined by embryonal placodes, are more common among females than males (5.7:1) as compared with focal lesions (3:1). These findings imply that there is the possibility of a different pathogenesis for focal and diffuse hemangiomas.That infantile hemangiomas distribute as they do may allow physicians to better predict the risk of complications. Questions remain as to whether infantile hemangiomas in other anatomic locations follow a similar paradigm; whether other vascular lesions distribute along similar embryonic planes of fusion or if this is unique to infantile hemangiomas; and why facial hemangiomas localize as they do along these anatomic sites.

Anatomical segmentectomy of the head of the pancreas along the embryological fusion plane: A feasible procedure?

Background. Less extensive resection of the head of the pancreas has been the procedure of choice recently for low-grade malignant neoplasms. The anatomical detail of the head of the pancreas is currently insufficient for segmental resection along the embryological fusion plane. Methods. The anatomy of the head of the pancreas was analyzed in 31 consecutive autopsy specimens. An anterior (n = 10) or posterior (n = 10) segmentectomy of the head of each pancreas was performed along the macroscopically found fusion plane. The pancreatic arteries, the portal vein, the bile duct, and the pancreatic duct were visualized by injecting 3 silicon dyes of different colors. Another 11 specimens were examined by pancreatography before and after anterior (n = 5) or posterior (n = 6) segmentectomy. Eight of these 11 specimens were stained immunohistochemically to reveal the distribution of pancreatic polypeptide cells after segmentectomy. Results. The cleavage between the anterior and posterior segments was discovered at the anterior inferior edge or at the posterior superior edge of the head of the pancreas. Anterior segmentectomy was accomplished while preserving the anterior and posterior pancreaticoduodenal arcades and the lower bile duct in the posterior segment. Posterior segmentectomy involved the removal of the lower bile duct and the posterior pancreaticoduodenal arcades. Pancreatography after segmentectomy showed the division of the ducts of Wirsung and Santorini with the peripheral branches. The immunohistochemical boundary of pancreatic polypeptide cells coincided with the surgical plane. These results showed the anterior and posterior segments were originated from the embryologically dorsal and ventral primordia, respectively. Conclusions. The current anterior or posterior segmentectomy of the head of the pancreas corresponded to the resection of the embryologically dorsal or ventral primordium, respectively. Anterior segmentectomy of the head of the pancreas might be a clinically applicable procedure; however, posterior segmentectomy involving the resection of the lower bile duct may be impractical. (Surgery 2000;128:822-31.)

Sternberg's canal - cause of congenital sphenoidal meningocele

We present a case of a 29-year-old female complaining of right-sided watery nasal discharge. Radiological investigations identified an intrasphenoidal meningocele. The origin of the meningocele was pinpointed to the right parasellar region and was confirmed surgically. The parasellar bony defect appeared to be due to persistence of the lateral craniopharyngeal canal (Sternberg's canal). Therefore, we assume a congenital origin for the intrasphenoidal meningocele found in the patient. Acquired bony defects of the sphenoid sinus are unlikely at the fusion planes of the different sphenoid bone components. Knowledge of the complex ontogeny of the sphenoid bone is an important key to differentiating between congenital and acquired sphenoid sinus meningoceles.

Radiation Therapy for Nonmelanoma Skin Carcinomas

Radiotherapy plays an important role in the management of appropriately selected skin carcinomas. Tumors of the eyelid, nose, and ear can be treated successfully with preservation of adjacent normal tissues. Tumors located in the embryologic fusion planes of the face can be irradiated with wide margins, either as primary or postoperative therapy. Radiotherapy has a significant role in the postoperative setting for patients with high-risk features in their pathologic specimens. Patients with NECS (Merkel cell carcinoma) have a high recurrence rate after surgical excision; these patients should undergo radiotherapy after resection of the clinically evident disease.

Intracellular Movements and Reorganization of Electrically Fused Sunflower Protoplasts

Early events during the fusion process of sunflower protoplasts have been investigated using videoenhanced microscopy and fine structure analysis. Electrical pulses applied for membrane breakdown induced an immediate cessation of cytoplasmic streaming, which resumed 0.5-5 min after pulsing. This observation may provide a marker for fusion product viability and an indicator to optimize fusion parameters. Correlated with the cessation of cytoplasmic streaming, internal vesicles formed probably from the ER. Two types of fusion events were observed: (1) protoplasts interconnected by cytoplasmic bridges showing no rounding up and subsequent individual cell divisions and (2) protoplasts connected by a broad fusion plane rounding up in ca. 1 h. This process was accompanied by accumulation of cytoplasm in the fusion plane, formation of cytoplasmic strands connecting the fused protoplasts, and dislocation of the nuclei. The creation of viable fusion products required not only membrane fusion but also complete reorganization of the cytoplasmic material.

Establishment of a cell-to-cell communication pathway between separate carpels during gynoecium development

In the evolutionarily advanced angiosperm flower, postgenital fusion is often involved in the formation of the female reproductive organ, the gynoecium. In the present study, we report on the early establishment of a cytoplasmic cell-to-cell communication pathway between the two fusing carpel primordia in Catharanthus roseus L. (periwinkle). Upon carpel contact, diffusible factors move between the two carpels to initiate the rapid redifferentiation of epidermal cells into parenchymatous cells, resulting in carpel fusion. Microinjection of the lipid-impermeable molecule, Lucifer Yellow CH (LYCH), into cells on either side of the epidermal fusion plane revealed that cytoplasmic continuity was established very early in this redifferentiation process. Electron-microscopic analysis confirmed that this inter-carpel cytoplasmic coupling was established by the formation of plasmodesmata produced between the contacting epidermal cells. The evolution of and role for this inter-carpel communication pathway is discussed in terms of the coordinate development of the gynoecium and its overall effect on reproductive fitness.

Embryologic Fusion Planes and the Spread of Cutaneous Carcinoma: A Review and Reassessment

It has long been held that embryologic fusion planes influence the spread of skin cancer. Embryologic fusion planes have been implicated in the depth of invasion, horizontal spread, and recurrence of cutaneous carcinoma. However, these structures have never been studied in detail. A review of the surgical literature reveals considerable confusion regarding the exact nature, location, and tumor interactions of these fusion planes. We review the gross and microscopic development of sites of embryologic fusion. We examine histologic sections through fusion sites in normally developed adult and fetal fresh cadaver specimens. Our studies, supported by our review of developmental anatomy, indicate that fusion planes do not persist as identifiable anatomic structures that would influence tumor spread.

Reinterpretation of vertebral structure in the Early Permian pelycosaurVaranosaurus acutirostris(Amniota, Synapsida)

ABSTRACT The vertebral anatomy of the rare Early Permian pelycosaur Varanosaurus acutirostris is described and figured. The atlanto–axial complex is generally similar to that in ophiacodont pelycosaurs. The atlantal centrum and the axial intercentrum are fused together; however, the plane of fusion between the two elements is directed posteroventrally, an angle opposite to the condition observed in Ophiacodon. The axial neural spine is large, and its anterior projection between the paired halves of the atlantal neural arch may have aided in preventing them from occluding the foramen magnum during rotation of the cranium relative to the vertebral column. Angulation of the articular surfaces of the zygapophyses of the anterior presacrai vertebrae probably allowed some rotation to occur posterior to the atlanto-axial complex. Dorsal vertebrae exhibit a complex of characters that include swollen neural arches, slightly tilted zygapophyseal facets and, in certain regions of the column, alternation in height an...

The nasolabial cyst-nasal hamartoma.

The nasolabial cyst is an uncommon midfacial cyst. Twenty-six patients with nasolabial cysts were treated at the New York Eye and Ear Infirmary from 1969 to 1986. Most of these lesions manifested facial deformity, unilateral nasal obstruction, and pain when infected. The nasolabial cyst is often unrecognized or confused with other intranasal masses, or fissural and odontogenic cysts. Infection of these lesions--which occurred in 50% of the patients--may mimic facial cellulitis, periodontal abscess, acute maxillary sinusitis, or nasal furuncles. This cyst is considered to be a hamartoma because of its developmental origin from entrapped epithelium in an embryonic fusion plane. Simple aspiration invariably leads to recurrence, and complete surgical excision is the accepted treatment. The nasolabial cyst should be considered in the differential diagnosis of intranasal masses, midface infections, and swelling in the nasolabial area.

Morphogenetic factors controlling differentiation and dedifferentiation of epidermal cells in the gynoecium of Catharanthus roseus

During postgenital fusion of the distal adaxial surfaces of the two originally separate carpel primordia of Catharanthus roseus (L.) G. Don, approx. 400 epidermal cells undergo rapid dedifferentiation into parenchymatous cells. To characterize the mechanism of the induction of dedifferentiation, various types of both water-permeable and water-impermeable barriers were placed between pre-fusion carpels. Barriers which did not allow the passage of water-soluble agents blocked dedifferentiation. Barriers which allowed passage of water-soluble agents did not block dedifferentiation of the contacting epidermal cells, implicating a diffusible agent or "morphogen" as the factor responsible for dedifferentiation. Experiments with barriers of known pore size demonstrated that the molecular weight of this morphogen was less than 1000. The two cell walls and thin cuticle present at the site of this postgenital fusion do not block the movement of some substances between the fusing carpels. Tracer studies with tritium-labeled asparagine confirmed that substances can be transported across the fusion plane.