BACKGROUND: Extramedullary plasmacytoma of the retroperitoneum is rare. Furthermore, plasmacytoma with anaplastic features can be confused with high grade @entity242 clinically and histologically, particularly when the initial immunohistochemical @entity5 markers are negative. However, paying attention to cytologic imprint smears can give valuable clues to the correct diagnosis. CASE: A 73-year-old male was admitted to our hospital with a recent history of @entity615 . Abdominal computed tomography revealed a large retroperitoneal mass (6.8 x 5.1 cm). The initial pathologic evaluation revealed a high grade pleomorphic @entity5 that failed to express multiple epithelial, mesenchymal, lymphoid and @entity320 immunohistochemical markers. Subsequent fresh tissue evaluation with touch imprints and immunophenotypic characterization confirmed the plasma cell origin of the @entity5 . Thorough retrospective review of the touch imprint smears clearly showed the plasmacytic cytologic features. Features of multiple @entity1582 were essentially absent. CONCLUSION: Performing cytologic imprint smears on fresh tissue material may help in making the correct diagnosis and is highly recommended.

Retroperitoneal extramedullary anaplastic plasmacytoma masquerading as XXXX : Report of a case with an unusual presentation and imprint smears.

@entity242 :: ('MESH:D012509', 'Disease') :: ['sarcoma'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'neoplasm'] @entity1582 :: ('MESH:D009101', 'Disease') :: ['myeloma'] @entity615 :: ('MESH:D001416', 'Disease') :: ['back pain'] @entity320 :: ('MESH:D008545', 'Disease') :: ['melanoma']
@entity242 :: (MESH:D012509,Disease) :: ['sarcoma']
