EUS‐FNA of the Merkel cell carcinoma metastasis to the pancreas: Cytomorphology and immunocytochemistry on direct cytological smears

Abstract

Increasing incidence of MCC warrants the inclusion of MCC in the differential diagnosis of tumours of small round blue cell morphology even in unusual sites. The cytomorphological features coupled with an ICC panel are usually enough to make a confident diagnosis of MCC. EUS-FNA is a minimally invasive technique which enables sampling adequate tissue for all the ancillary methods eventually needed to support the diagnosis.

The diagnostic utility of Merkel cell polyomavirus immunohistochemistry in a fine needle aspirate of metastatic Merkel cell carcinoma of unknown primary to the pancreas

“…23 However, metastases to the pancreas are exceedingly rare; only 19 cases have been reported in the literature. [7][8][9][10][11][12][13][14][15][16][17][18][19] In these cases, the pancreas metastases were almost always preceded by nodal recurrence of primary MCCs or concomitant extra-pancreatic metastases.…”

“…We FNA). 8,18,19 We report a case of MCC from an unknown primary manifesting as an axillary mass and a pancreatic metastasis. …”

“…[4][5][6] Pancreatic involvement by MCC is rare with 19 reported cases in the literature. [7][8][9][10][11][12][13][14][15][16][17][18][19] To date, only 8 cases have been diagnosed by endoscopic ultrasound-guided fine-needle aspiration cytology (EUS-FNA). 8,18,19 We report a case of MCC from an unknown primary manifesting as an axillary mass and a pancreatic metastasis.…”

Neoplastic metastases to the endocrine glands

“…Lung cancer metastases are usually CK20 negative. CD56 can be a better marker for neuroendocrine differentiation when dealing with small-cell neoplasms (Stoos-Veic et al 2017). In general, the suggested primary panel for a small-cell tumour aspirated from the pancreas should employ leucocyte common antigen-A (LCA), TTF-1, CK20, Pan Cytokeratin, CD56, CD117 and possibly one additional neuroendocrine marker.…”

“…In general, the suggested primary panel for a small-cell tumour aspirated from the pancreas should employ leucocyte common antigen-A (LCA), TTF-1, CK20, Pan Cytokeratin, CD56, CD117 and possibly one additional neuroendocrine marker. Depending on the medical history, other antibodies may be used (Stoos-Veic et al 2017).…”