26
Mediastinum
Fig. 26.11 Seminoma. (A) Loosely cohesive large mononuclear tumor
cells are seen in association with necrotic debris and stripped nuclei in
the background. Direct smear of fine-needle aspirate (Papanicolaou x MP).
(B) Loose aggregates of epithelioid histiocytes and chronic inflammatory
cells are present, suggestive of associated granulomatous reaction. A
seminoma cell is also seen here (arrow). Direct smear of fine-needle aspirate
(Papanicolaou x MP). (C) The tumor cells contain large, round to ovoid,
and moderately pleomorphic nuclei, delicate nuclear membrane, vesicular
chromatin pattern, prominent solitary nucleoli, and fragile cytoplasm. Note
the presence of reactive lymphoid cells in the background. Direct smear of
fine-needle aspirate (Papanicolaou x HP). (D) Clumps of seminoma cells seen
in cell block sections may be mistaken as non-small-cell carcinoma (left).
The tumor cells show membranous staining for CD117 (right). Cell block
sections of fine-needle aspirate (H&E and immunostain for CD117; x MP and
MP, respectively). (E) There are lobules of seminoma cells associated with
granulomatous inflammation (arrow). Histologic section of surgical specimen
(H&E x MP).
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