title: Recurrence of retroperitoneal Merkel cell carcinoma. A case report.
abstract: BACKGROUND
  Merkel cell carcinoma (MCC) is a neuroendocrine malignant neoplasm that usually has its primary location on the skin. It often metastasizes to lymph nodes, liver, lungs, bones and brain. Actually there have been few cases of MCC of the retroperitoneal region without a primary skin lesion.
  
  
  METHODS
  Our case is a male of 55 year old who initially underwent a partial resection (R1) of a bulky pelvic mass; the histopathological analysis and the immunoistochemistry showed the presence of neuroendocrine Merkel cells. The patient underwent 6 cycles of postoperative chemotherapy (carbon platinum and etoposide) and adjuvant radiotherapy. Afterwards the patient underwent surgery again with the complete resection of the tumour.
  
  
  CONCLUSIONS
  The histopatological and immunoistochemistry analysis of the first and the second surgical samples confirmed the diagnosis of a retroperitoneal high-grade neuroendocrine carcinoma with a high mitosis index. The immunoistochemistry profile showed neoplastic cell with: CD 20+, synaptophysin +, TTF-1-, neurofilaments +, CK 7-, chromogranin, Ki67 90%. In the patient's medical history no skin localizations were mentioned.
  
  
  CONCLUSIONS
  The hypothesis of a MCC with a primary retroperitoneal localization has been strength by the histopathological and immunoistochemistry analysis of two intra-operative samples from two different surgical procedure and from the absence of either a primary skin location or of secondary recurrences. Is therefore reinforced the theory that from a cell into a retroperitoneal lymph node can arise a retroperitoneal mass originating a Merkel cell tumour.
authors.forename: Luca
authors.initials: L
authors.lastname: Pio Evoli
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Marino
authors.forename: Emanuele
authors.initials: E
authors.lastname: Rosati
authors.forename: Patrizia
authors.initials: P
authors.lastname: Ricci
authors.forename: Luigina
authors.initials: L
authors.lastname: Graziosi
authors.forename: Emanuel
authors.initials: E
authors.lastname: Cavazzoni
authors.forename: Annibale
authors.initials: A
authors.lastname: Donini
mesh_terms: D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D014408:Biomarkers, Tumor / Q000032:analysis; D016190:Carboplatin / Q000008:administration & dosage; D015266:Carcinoma, Merkel Cell / Q000737:chemistry / Q000473:pathology* / Q000556:secondary / Q000628:therapy; D017024:Chemotherapy, Adjuvant; D003131:Combined Modality Therapy; D005047:Etoposide / Q000008:administration & dosage; D006801:Humans; D007813:Laparotomy; D008113:Liver Neoplasms / Q000556:secondary; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000601:surgery; D009392:Nephrectomy; D018714:Radiotherapy, Adjuvant; D012186:Retroperitoneal Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000628:therapy
chemical_list: D014408:Biomarkers, Tumor; D005047:Etoposide; D016190:Carboplatin