Hyperplastic Luschka ducts: a mimic of adenocarcinoma in the gallbladder fossa

Ducts of Luschka are a developmental abnormality found within the gallbladder fossa in up to 10% of cholecystectomy specimens. They are most often encountered by surgeons when injured during laparoscopic or open cholecystectomy, leading to bile leakage and subsequent peritonitis. Histologically, they are typically composed of lobular aggregates of small ductules lined by bland, cuboidal-to-columnar biliary-type epithelium, associated with centrally located, larger ductules surrounded by concentric fibrosis. We have identified 6 cases of florid Luschka duct proliferation in which the ductules demonstrated irregular growth pattern, loss of characteristic concentric fibrosis, and epithelial atypia that strongly suggested the diagnosis of invasive pancreatobiliary adenocarcinoma or metastatic adenocarcinoma involving the gallbladder serosa. Two of the cases were initially diagnosed as invasive adenocarcinoma, whereas the other 4 were sent for consultation to rule out adenocarcinoma. All cases were associated with marked acute and chronic cholecystitis with mucosal ulceration, cholelithiasis, and thickening of the gallbladder wall. The ducts of Luschka were located within the rim of adherent liver in all 6 cases and the gallbladder serosa in 5 cases. Limited follow-up information was available for all patients with no documentation of progressive disease. Awareness and proper recognition of the anatomic location and histologic features are imperative in distinguishing florid ducts of Luschka from both non-neoplastic conditions and most importantly adenocarcinoma.     

Melanocytic nevi with an atypical epithelioid cell component: clinical, histopathologic, and fluorescence in situ hybridization findings

Combined melanocytic nevi can contain a phenotypically distinct population of large atypical epithelioid cells in a background of smaller banal-appearing melanocytes. On the basis of the pattern of proliferation and degree of pigmentation, nevi with this pattern have been referred to as nevi with an atypical epithelioid cell component (N-AECC). When N-AECC display sheet-like or an expansile nodular growth pattern, notable cytologic atypia, and any level of mitotic activity, they can be difficult to distinguish from melanoma. The clinical history and appearance of these lesions may similarly raise concern for melanoma. In view of this diagnostic problem, we present 28 cases of N-AECC from our dermatopathology consultation and in-house practice. All 28 cases were found to be negative on the basis of fluorescence in situ hybridization (FISH) for imbalanced chromosomal aberrations commonly found in melanoma. The clinical outcomes showed a benign clinical course for all cases for which the outcome information was available. FISH analysis also revealed that, in 4 of 28 cases (14%), the AECC of the lesion demonstrated polyploidy localized to the large epithelioid cell component. This is likely more common among cases of N-AECC that have an atypical spitzoid epithelioid cell component, particularly those with obvious senescent nuclear changes. Care must be taken to avoid the pitfall of misinterpreting these FISH findings as changes consistent with melanoma. The use of ancillary testing methods including FISH may be beneficial in improving the diagnostic accuracy involved in making the distinction of N-AECC from melanoma. Further, we report a novel finding of polyploidy seen in certain cases of benign N-AECC.     

Impact Fracture Resistance of Two Titanium‐Abutment Systems Versus a Single‐Piece Ceramic Implant

Background: The number of patients with oral implants has increased significantly. However, the literature addressing the effect of impact force on titanium and/or ceramic implants is inconclusive. This study sought to determine the fracture resistance to impact load of titanium and ceramic endosseous oral implants. Materials and Methods: Endosseous oral implants were vertically positioned in two different mounting media: brass and a bone‐simulation material. The implant configurations tested included an experimental one‐piece Y‐TZP implant and a commercially available titanium implant (external hex) with both titanium and zirconia abutments. The specimens were subjected to an impact load using a pendulum impact tester with tup weights varying from 0.9 to 4.5 kg delivered at a radius of 40.64 mm. Loads were delivered to the abutment at a point 4.27 mm above the implant fixture and block junction. Statistical differences (p < .05) were established using the F‐test for variances and, when different, t‐test assuming unequal variances. Results: For implants clamped in brass, the titanium implant with titanium abutment required the greatest energy to fracture the implant‐abutment system (only the abutment screw failed). The ceramic implant and ceramic abutment on titanium implant presented the lowest fracture energy (p < .01). No significant differences were observed when different systems were inserted into the foam blocks of the bone substitute (p > .25). Conclusion: This investigation showed that the fracture energy of two titanium‐abutment systems versus a single‐piece Y‐TZP implant in foam blocks simulating bone elastic modulus was not different, and that differences occurred when the embedding material elastic modulus was increased an order of magnitude.     

Radiographic study of the mandibular retromolar canal: an anatomic structure with clinical importance

Introduction

The retromolar canal is an anatomic structure of the mandible with clinical importance. This canal branches off from the mandibular canal behind the third molar and travels to the retromolar foramen in the retromolar fossa. The retromolar canal might conduct accessory innervation to the mandibular molars or contain an aberrant buccal nerve.

Methods

Patients referred for panoramic radiography were consecutively enrolled, provided a limited cone-beam computed tomography (CBCT) scan had also been taken in the area of interest. Radiographs were retrospectively screened for the presence of a retromolar canal, and linear measurements (distance to second molar, height, width) were taken.

Results

One hundred twenty-one sides in 100 patients were evaluated (100 unilateral and 21 bilateral cases). A total of 31 retromolar canals were identified with CBCT (25.6%). Only 7 of these canals were also seen on the corresponding panoramic radiographs. The existence of a retromolar canal was not statistically related to gender or side. With regard to the linear measurements, the mean distance from the retromolar canal to the second molar was 15.16 mm (±2.39 mm), the mean height of the canal was 11.34 mm (±2.36 mm), and the mean width was 0.99 mm (±0.31 mm).

Conclusions

This radiographic study documents a frequency of 25% for the presence of a retromolar canal. The clinician is advised to preserve this anatomic variation when performing surgery in the retromolar area and to consider additional locoregional anesthesia in the case of failed mandibular block anesthesia.     

Characteristics and dimensions of the Schneiderian membrane: a radiographic analysis using cone beam computed tomography in patients referred for dental implant surgery in the posterior maxilla

Objectives: To determine the dimensions of the Schneiderian membrane using limited cone beam computed tomography (CBCT) in individuals referred for dental implant surgery, and to determine factors influencing the mucosal thickness. Material and methods: The study included 143 consecutive patients referred for dental implant placement in the posterior maxilla. A total of 168 CBCT images were taken using a limited field of view of 4 × 4 cm, 6 × 6 cm, or 8 × 8 cm. Reformatted coronal CBCT slices were analyzed with regard to the thickness and characteristics of the Schneiderian membrane in nine standardized points of reference. Factors such as age, gender, or status of the remaining dentition that could influence the dimensions of the Schneiderian membrane were evaluated using univariate and multivariate linear regression models. Results: The thickness of the Schneiderian membrane exhibited a wide range, with a minimum value of 0.16 mm and a maximum value of 34.61 mm. The highest mean values, ranging from 2.16 to 3.11 mm, were found for the mucosa located in the mid‐sagittal regions of the maxillary sinus. The most frequent mucosal findings diagnosed were flat thickenings of the Schneiderian membrane (62 positive findings, 37%). For the multivariate linear regression model, only gender had a statistically significant influence on the mean overall and mid‐sagittal thickness of the sinus mucosa. Conclusion: There is great interindividual variability in the thickness of the Schneiderian membrane. Gender seems to be the most important parameter influencing mucosal thickness in asymptomatic patients. Future studies are needed to assess the therapeutic and prognostic consequences of mucosal alterations in the maxillary sinus. To cite this article:
Janner SFM, Caversaccio MD, Dubach P, Sendi P, Buser D, Bornstein MM. Characteristics and dimensions of the Schneiderian membrane: a radiographic analysis using cone beam computed tomography in patients referred for dental implant surgery in the posterior maxilla.
Clin. Oral Impl. Res. xx , 2011; 000–000.
doi: 10.1111/j.1600‐0501.2010.02140.x     

Vascular Endothelial Growth Factor Receptor-3 Mediates Induction of Corneal Alloimmunity

There are no studies so far linking molecular regulation of lymphangiogenesis and induction of adaptive immunity. Here, we show that blockade of vascular endothelial growth factor receptor-3 (VEGFR-3) signaling significantly suppresses corneal antigen-presenting (dendritic) cell trafficking to draining lymph nodes, induction of delayed-type hypersensitivity and rejection of corneal transplants. Regulating the function of VEGFR-3 may therefore be a mechanism for modulating adaptive immunity in the periphery.     

Unusual renal pathology associated with a Wilms tumor in a 15-month-old infant

Beckwith-Wiedemann syndrome is an overgrowth dis-order that predisposes to the development of a variety of malignancies including Wilms tumor. Pathologists may suspect the presence of Beckwith-Wiedemann syndrome, which may be clinically subtle, on the basis of the histopathology of the renal parenchyma adjacent to a Wilms tumor. These kidneys typically harbor multiple nephrogenic rests (especially perilobar nephrogenic rests), and their medullas have blunted papillae resulting from excessive fibromyxoid stroma, decreased collecting ducts, and decreased Henle loops. This complex of findings constitutes the so-called Beckwith Medulla. Extensions of this stroma-rich medulla into the cortex results in characteristic dysplastic medullary-ray nodules. Identification of these histologic abnormalities by the pathologist should prompt the clinician to evaluate the child for Beckwith-Wiedemann syndrome. Proper screening of these children can allow for early detection of cancers and treatment while these cancers are curable.