Peritoneal implant

Robitaille R, Dusseault J, Henley N, Desbiens K, Labrecque N, Halle J-P. Inflammatory response to peritoneal implantation of alginate-poly-L-lysine microcapsules. Biomaterials 2005, 26, 4119 1127. 

Desmoplastic small round cell tumor Young adults, often adolescent boys. Abdomen and pelvis, peritoneal implants. Round/oval cells in desmoplastic stroma in classic cases, other cases with variable morphology Vimentin+, cytokeratin+, EMA+, desmin+, WT1 + RT-PCR for EWS-WT1... 

An efficient porons chamber system to convert Factor VII to Vila was developed and implantation of this chamber, in vivo, was shown to be effective. The chamber containing immobilized Factor Xlla was able to generate Factor Vll-dependent bypass activity for at least 3 days as a peritoneal implant in guinea pigs and for up to 1 month when tested in rhesns monkeys. 

In ovariectomized rats treated with a total of 500 mg of the compound diosgenin over a 45-day period (via an intra-peritoneally implanted tricalcium phosphate drug delivery system), increases in body weight and spleen weight were observed along with a slight increase in wet adrenal weight. 

Presence of ascites, omental involvement, serosal implants, mesenteric involvement, peritoneal implants, and interruption of the anterior peritoneal line are the most frequently described ultrasonographic findings in patients with peritoneal metastasis. Accessory findings are represented by liver metastasis, lymphadenopathies, and gallbladder... 

Frequently, in malignant ascites, the fluid is echogenic (due to the presence of blood and/or neoplastic cells Fig. 18.1),septa are often present (Fig. 18.2), bowel loops are fixed and smashed for mesenteric involvement (Fig. 18.3), and serosal and parietal peritoneal implants are often visible. Indeed, abun-... 

Peritoneal parietal and serosal implants are visible on ultrasound as soft tissue masses or nodules adhering to the peritoneum, as irregularity or interruption of the anterior hyperechoic peritoneal line (Fig. 18.7). Visualisation is facilitated by the presence of ascites. The ultrasonographic study of the peritoneal line is facilitated by the use of high frequency ultrasound probes, which allow also visualization of very small peritoneal implants (Fig. 18.8 Lorenz et al. 1990). Peritoneal implants, serosal implants, and interruption of the anterior hyperechoic peritoneal line are present at the rates of about 54,19, and 16%, respectively in patients with peritoneal carcinomatosis (Rioux and Michaud 1995). 

Fig. 18.7. Small peritoneal implants are clearly visible as hypoechoic nodules on the peritoneal line (a-c) or as irregularity (>) of the peritoneal line (d). d Echogenic ascites is also clearly visible...

Differential diagnosis Familiarity with history of ovarian transposition is crucial to establish the correct diagnosis. The differential diagnosis includes mucocele of appendix, peritoneal implants, colonic masses, lymphoceles, and lymph node metastases. 

Peritoneal implants appear as solitary, or more often as multiple soft tissues lesions (Fig. 10.5), which display a wide range of size and patterns. Implants may be distributed along the peritoneal surfaces in a linear and often linear and nodular pattern (Fig. 10.6) they may also coalesce and surround the viscera or the diaphragm in a plaque- or coatlike manner. The majority of these implants enhance with contrast media some are cystlike and may mimic loculated fluid. Implants from serous tumors may have calciflcations (Fig. 10.7). 

Netlike omental involvement is more difficult to evaluate. Implants of the diaphragm consist of nodular or plaquelike lesions. Peritoneal implants of liver or spleen may result in scalloping of the surface. Ligaments may appear thickened due to peritoneal metastases. Implants on bowel or mesentery can cause tethering of loops and may lead to obstruction. Bowel obstruction,however, results more commonly from intestinal wall involvement than from serous implants. Mesenteric lesions appear as thickening of the root of the mesentery, and often display a stellate radiating pattern. 

The depiction of peritoneal implants depends on the size and presence of ascites. The latter improves the con-spicuity, especially of smaller lesions. However, implants less than 1 cm are detected with a sensitivity of only 25%-50% with spiral CT technique [23]. In this study, CT performance improved to a sensitivity of 85%-93% and a specificity of 91%-96% in detecting extrapeMc peritoneal disease larger than 1 cm in size [23]. Contrast-enhanced CT and MRl aid in the depiction of peritoneal implants. MRl seems similar to CT in the assessment of abdominal peritoneal implants and seems superior in the assessment of pelvic peritoneal details [24]. 

Fig. 10.9. Umbilical metastasis. Sister Mary Josefs nodule is a peritoneal implant to the umbilicus. In this patient, a solid 1.5-cm lesion (arrow) is demonstrated. Other signs of peritoneal tirnior spread include large amounts of ascites and focal thickening of the peritoneum in the right paracolic gutter...

Stage III consists ofextrapelvic peritoneal implants and/or inguinal or retroperitoneal lymphadenopathy. Peritoneal lesions outside the pelvis, omental, or mesenteric implants are typical findings in stage III ovar-... 

Fig. 10.16. Nonoptimally resectable ovarian cancer. Multiple peritoneal implants (arrows) are demonstrated on the liver surfece and lesser sac. The latter is distended due to ascites. The implants located in the interlobar fissure (asterisk) and lesser sac (asterisk) are considered nonoptimally resectable...

Fig. 10.23a,b. Ovarian cancer recurrence. Coronal CT scans (a, b) in a patient with advanced recurrent clear cell cancer show multiple, predominantly cystic peritoneal implants throughout the abdomen and pelvis. The liver surface is compressed by surface implants (asterisk) (a, b). Multiple enlarged lymph nodes are seen in the right pelvis and root of the mesentery (b). Associated findings in this case include bilateral pleural effusion and a thrombus in the left femoral vein... 

CT currently has a staging accuracy of 53-92% (Yoshida). It is the staging modality of choice. The high resolution of MDCT scanners gives information about the size of the tumor, its extension, localization of peritoneal implants, and lymph node enlargement. 

Peritoneal spread. Peritoneal seeding is caused by distribution of tumor cells into the normal peritoneal fluid. Peritoneal metastases are usually nodular soft tissue lesions or plaque-like thickening of the parietal or visceral peritoneum. They usually show moderate enhancement. Diagnosing small peritoneal implants can be difficult, with very low detection rates for CT (Coak-... 

---