Here is the primary ovarian tumor -- a bilateral serous borderline tumor.
Note the papillary formations lined by serous epithelium.
This S-LMP tumor was accompanied by non-invasive omental implants, which grow in the septae of the fat, but does not actually invade and destroy the tissues. This would be the 'epithelial' type of non-invasive implants.
Here is an example of non-invasive desmoplastic implants on the colonic serosa. Colonic muscularis propria on the left is well demarcated from the inflamed, hemorrhagic and desmoplastic implant tissue on the right. Note the jagged neoplastic glands in the upper right.
A higher power view of those jagged glands shows no significant atypia -- the irregular shaped gland is surrounded by lots of spindled desmoplastic stroma.
Other areas of the non-invasive implant showed widespread psammomatous calcifications embedded in the same type of desmoplastic stroma.
Serous borderline tumors are associated with peritoneal or omental implants in approximately 15-30 of cases.1 There is much debate regarding whether these implants originate from the primary ovarian tumor, or if they are separate synchronous primary tumors arising from the mesothelium. In any case, implants are broadly divided into invasive and non-invasive. Non-invasive implants are further sub-divided into epithelial type and desmoplastic type.
In epithelial non-invasive implants, papillary serous borderline tumor grows within lobules of fat or on the surface of the peritoneum or omentum. The surrounding tissue is not invaded or destroyed. In desmoplastic non-invasive implants, a plaque of sorts forms on the peritoneal surface, which contains neoplastic glands surrounded by reactive, desmoplastic and inflammed stroma. Again, the subjacent tissue is not altered or destroyed by the implanted tissue.
Serous borderline tumors within non-invasive implants are considered indolent, non-aggressive entities with a favorable prognosis. However, these studies generally follow patients only 5 years out. In a 2006 study conducted at MD Anderson Cancer Center, 80 patients with serous borderline tumors with non-invasive implants were followed from 5 years onward, with followup ranging from 5 to 31 years. Results indicated that 44% of patients eventually experienced recurrence after a long followup and 25% died from the disease (Silva).
As mentioned above, non-invasive implants may not warrant their almost benign status when one follows these patients in the long term. In a study of 80 patients with S-LMP tumors, 35 out of the 80 patients (44%) eventually developed tumor recurrence after initial diagnosis and treatment. 10% had recurrence in less than 5 years, 19% had recurrence between 5-10 years, 10% had recurrence between 10 and 15 years and 5% had recurrence 15 years after resection of the primary tumor. Furthermore, 27 cases recurred as low grade serous carcinoma and 20 of those patients died from the disease (Silva).
♣ Non-invasive implants come into two flavors, epithelial and desmoplastic.
♣ Serous borderline tumors with non-invasive implants have historically been considered indolent and benign, but new research shows that a significant percentage may recur and lead to the death of the patient.
1 Fletcher CDM, ed. Diagnostic Histopathology of Tumors. 3rd Ed. Philadelphia, PA: Elsevier; 2007: 571-2.
2 Silva EG, Gershenson DM, Malpica A et al. The Recurrence and the Overall Survival Rates of Ovarian Serous Borderline Neoplasms With Noninvasive Implants is Time Dependent. Am J Surg Pathol 2006;30:1367-1371.