Impact of affected lymph nodes on long-term outcome after surgical therapy of alveolar echinococcosis.

Abstract

Alveolar echinococcosis (AE) is a life-threatening helminthic disease. In humans, AE mostly affects the liver; the regional hepatic lymph nodes may be involved, indicating dissemination of AE from the liver. To achieve complete removal of the disease, enlarged hepatic lymph nodes may be resected during surgical treatment. We evaluated the frequency of affected lymph nodes by conventional microscopic and immunohistochemical analyses including detection of small particles of Echinococcus multilocularis (spem). Furthermore, we analyzed the association of resection of enlarged and affected lymph nodes with long-term outcome after surgical therapy of patients who underwent surgery with curative intent. We identified 43 patients who underwent hepatic surgery with curative intent with lymph node resection for AE. We analyzed the cohort for the manifestation of the parasite in the resected lymph nodes by conventional histology and by immunohistochemistry and compared these data with the further course of AE. Microscopically infected lymph nodes (laminar layer visible) were found in 7 out of these 43 patients (16%). In more than three quarters (25/32) of all specimens investigated, lymph nodes showed spems when stained with antibody against Em2G11, a monoclonal antibody specific for the Em2 antigen of the Echinococcus multilocularis metacestode. Most frequently, lymph nodes were resected due to enlargement. The median size of microscopically affected lymph nodes was 2cm (range, 1.2 to 2.5cm), the median size of immunohistochemically and non-affected lymph nodes was 1.3cm each (range, "small" to 2.3 or 2.5cm, respectively). Median follow-up was 8years for all patients, 5years for patients with lymph node resection, and 4years for patients with infested lymph nodes. Overall, recurrent disease was seen in ten patients (10/109; 9%) after a median period of 1.5years (range, 4months to 4years). None of the seven patients with conventionally microscopically affected lymph nodes suffered from recurrent disease. One patient with negative resected nodes and one patient with spems showed recurrent disease after 4 and 35months, respectively. Lymph node involvement in AE is frequent, particularly when evaluated by immunohistochemical examination of lymph nodes with the monoclonal antibody Em2G11. Affected lymph nodes tend to be larger in size. Lymph node involvement is not associated with recurrent disease and therefore warrants further analysis of the biological significance of lymph node involvement.