Lymph Node Involvement in Multicystic Peritoneal Mesothelioma:

Epithelioid Lesions of the Serosa

Context.—Diagnosing epithelioid serosal lesions remains a challenge because numerous different processes—primary or secondary, benign or malignant—occur in body cavities, some of which are very rare.

Objectives.—To review the newest literature and to describe the morphologic criteria and immunohistochemical markers that are useful for distinguishing epithelioid serosal lesions.

Data Sources.—Previously published literature concentrating on the newest research findings. Earlier reviews are principally referred to for established diagnostic criteria.

Conclusions.—Immunohistochemistry with a panel of antibodies has made the diagnosis of epithelioid serosal lesions very reliable. When deciding on antibodies used in differential diagnosis, it is important to consider tumor location, clinical and radiologic information, and morphologic features. Immunohistochemistry is less useful in the differential diagnosis of benign versus malignant mesothelial lesions. The diagnosis of benign versus malignant mesothelial proliferations still relies on the histologic criteria of invasion.

Multicystic peritoneal mesothelioma: outcomes and patho-biological features in a multi-institutional series treated by cytoreductive surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

AIM

This retrospective multi-institutional study addresses the role of surgical cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC) in the treatment of multicystic peritoneal mesothelioma (MCPM). MCPM is an uncommon tumour with uncertain malignant potential and no current standard therapy. Additionally, poorly defined pathological and biological features of this disease were investigated.

METHODS

Twelve patients with MCPM underwent 14 procedures of cytoreduction and HIPEC in two Italian referral centres. Nine patients had recurrent disease after previous debulking (one operation in six patients, two in two, four in one). Biological markers related to mesothelioma origin and clinical features were assessed by immunohistochemical studies.

RESULTS

Median follow-up was 64 months (range 5-148). Optimal cytoreduction (residual tumour nodules ≤2.5 mm) was performed in all the procedures. One grade IV postoperative complication (NCI/CTCAE v.3.0) and no operative death occurred. All the patients are presently alive with no evidence of disease, including two patients who underwent the procedure twice, due to locoregional disease recurrence. Five- and ten-year progression-free survival was 90% and 72%, accounting for a. statistically significant difference (P = 0.0001) with progression-free survival following previous debulking surgery (median 11 months; range 2-31). All cases showed low proliferative activity assessed by mitotic rate and Ki-67 expression.

CONCLUSIONS

MCPM is a borderline tumour with a high propensity to local-regional recurrence. Definitive tumour eradication by means of cytoreduction and HIPEC seems more effective than debulking surgery in preventing disease relapse. Low mitotic rate and poor Ki-67 expression might be related to the peculiar behaviour of MCMP.