Primary neuroendocrine carcinoma of inguinal lymph node

Ninety-seven percent of carcinoid tumours are located in the gastro-intestinal tract or in the bronchopulmonary tree. Inguinal lymph nodes as the primary tumour site for neuroendocrine carcinoma represent an unusual localisation and in the literature were described only in two case reports.

A 64 year old previously healthy Caucasian female presented with a 2-months' history of enlargement of an inguinal lymph nodes on the right side. The removed lymph node showed histological and immunhistochemical evidence of neuroendocrine differentiation (positive for synaptophysin, cytokeratin 20, neuron-specific enolase and chromogranin A). The patient underwent repeated extensive investigations including CT and NMR scans, classical endoscopy, video capsule endoscopy of the small intestine, Octreotide- and MIBG scintigraphy, but no other primary tumour was found. Furthermore, there was no evidence of Merkel cell carcinoma by dermatological examinations.

A possible explanation for the presence of neuroendocrine carcinomas within lymph nodes is to postulate the malignant transformation of preexisting intranodal epithelial nests as previously described in lymph nodes located close to salivary glands, thyroid gland, breast tissue and pancreas. After surgical removal of the affected lymph node we meanwhile follow the patient for more than 3 years without signs of disease recurrence. Therefore we consider this as a primary carcinoid tumour in an inguinal lymph node.