Neoplastic proliferation of plasma cells is called plasma cell dyscrasias, and these neoplasms can present as a solitary neoplasm or multiple myeloma. Extramedullary plasmacytoma, in particular pancreatic plasmacytoma, is a rare manifestation of multiple myeloma. Although computerized tomography is useful for the diagnosis of extramedullary plasmacytoma, there are no specific radiologic markers that distinguish it from adenocarcinoma. Histological confirmation by biopsy is necessary for accurate diagnosis and management of the tumor. Endosonography is the most sensitive method for the diagnosis of pancreatic tumors, and the use of fine needle aspiration by endosonography is associated with a lower risk for malignant seeding and complications. Here, we report a case of pancreatic plasmacytoma in newly identified multiple myeloma as diagnosed by endosonography. Endosonography is a reliable and rapid method for the diagnosis of extramedullary plasmacytoma. Therefore, endosonographic fine needle aspiration should be the first choice for histological evaluation when pancreatic plasmacytoma is suspected. Ideally, the pathology would be performed at the same site as endosonographic biopsy.

An uncommon manifestation of multiple myeloma is extramedullary plasmacytoma. It is generally localized to nasal fossa and rarely involves the pancreas. On imaging, such a pancreatic mass may mimic adenocarcinoma[1,2].

We present here a case of a 64-year-old man who was referred to our endoscopy unit for endosonographic (EUS) fine needle aspiration (FNA) for a pancreatic mass.

EUS (Fujinon, Tokyo, Japan) revealed a 3 cm heterogeneous focal mass in the head of the pancreas (Figure 1). Neoplastic cells were detected by FNA (22 G; Cook Endoscopy, Winston-Salem, NC, United States), and plasmacytoma was diagnosed by the cytopathologist (Figure 2). Since plasmacytoma features are nonspecific on EUS and resemble other neoplasms including adenocarcinoma, plasmacytoma should be included in the differential diagnosis of a pancreatic mass, especially in advanced stage multiple myeloma patients. EUS-FNA is a fast and reliable technique for the diagnosis of plasmacytoma.

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Figure 1 Endosonographic view of mass.

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Figure 2 Cytopathologic findings of pancreatic mass obtained by endosonographic fine needle aspiration. A: Neoplasic plasmacytoid cells, mitose in the middle (× 100, Papa-nikolaou stain); B: Neoplasic plasmacytoid cells (× 100, May-Grunwald-Giemsa).