A case of long-term recurrence-free poorly differentiated neuroendocrine carcinoma of lymph nodes treated by surgical resection without any chemotherapy

Abstract

A 77-year-old man presented with a 2-month history of an enlarged right inguinal lymph node. Diagnostic excisional biopsy of the inguinal lymph node proved it to be a poorly differentiated neuroendocrine carcinoma by histological and immunohistological analyses. We diagnosed a poorly differentiated neuroendocrine carcinoma by histological examination and immunohistological analysis of the resected inguinal lymph node. We performed computed tomographic examination and positron emission tomography, which identified lymph node involvement without any signs of other tumors. Because these tumors had grown expandingly and had been encapsulated locally, we performed an operation to dissect all of the involved lymph nodes. Direct invasion to the right external iliac artery was not detected, and two of the enlarged lymph nodes were successfully resected without any complications. Pathologically, the resected specimen was diagnosed as a neuroendocrine carcinoma with a negative surgical margin and it was similar to the histology of the inguinal lymph node previously resected. The patient had no recurrence for 3 years without receiving any adjuvant treatment. There have been no reports describing a case of poorly differentiated neuroendocrine carcinoma, of unknown origin, which metastasized to other lymph nodes. Although further studies are required, complete resection of the involved lymph nodes should be considered as a choice for localized, expanding growth-pattern disease even if it is undifferentiated type.

Microsatellite Instability-high-positive Cancer of Unknown Primary Origin with a Long-term Survival after Surgery Alone

“…Although five other CUP cases were reported to have survived after surgical treatment alone in Japan (18)(19)(20)(21)(22) (Table 4), to our knowledge, this is the first report of a successfully treated case of MSI-H CUP. Of the six cancer cases of unknown primary reported in Japan (including our case) with a long-term survival after surgery alone, four involved intra-abdominal lymph nodes.…”

Poorly Differentiated Neuroendocrine Carcinoma in a Perigastric Lymph Node from an Unknown Primary Site

“…There are two models of tumor progression for these nodal neuroendocrine carcinomas from an unknown primary site [5,6]: nodal neuroendocrine carcinoma originates from the LN via formation of malignant precursor cells; and it originates from a spontaneously regressed primary lesion. According to a study reported by Kuwabara et al [7], primary nodal neuroendocrine carcinoma follows a less aggressive course than its metastatic nodal involvement.…”

“…A small number of previous case reports have also described treatment of PDNEC of unknown primary origin by surgical resection. Hisamori et al [6] reported two cases of PDNEC of unknown primary origin in an inguinal and a pancreaticoduodenal LN, respectively, which were treated by surgical resection alone [8]. Considering the fact that both patients achieved long-term disease-free survival with LN dissection only, their cases probably could have originated from the affected LN itself.…”