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Case 306 - Discussion

Hematopathology Case

CD3

CD3

ALK1

CD15

CD30

CD30

CD20

BOB1

OCT2

PAX5
EBER CD2

CD5

CD5

CD7

CD7

Granzyme B

Granzyme B

Perforin

Perforn

TIA1

TIA1

DIAGNOSIS

  • Spleen, splenectomy:
    • Peripheral T-cell lymphoma, not otherwise specified, with gamma/delta T-cell derivation
    • Minor population of CD30+ large pleomorphic cells, likely representing transformation from the small cell component
  • Flow cytometry, spleen:
    • A dominant population of atypical T-cells at lower side-scatter, positive for CD2, CD3, cCD3, CD7, CD45, CD56 (small subset), and TCR gamma/delta ; and negative for CD4, CD5, CD8, CD16, CD30, CD57, TCR alpha/beta
    • A minor population of T-cells at higher side-scatter, positive for CD2, CD3, CD7, CD30 (subset), CD45, CD56 (small subset), and TCR gamma/delta; and negative for CD4, CD8, and TCR alpha/beta
  • Cytogenetic studies, spleen:
    • 46,XY, psu dic (12;1))(p13;p12)[2] / 48~52,sl,+5,+20,+22[cp6] / 92~96, sdl1 x 2 [cp2] / 46,XY[10]
  • FISH studies, spleen:
    • Negative for gain of 7q31 that would be suggestive for isochromosome 7

DISCUSSION

  • The spleen shows intact architecture with expansion of the red pulp and reduction of the white pulp. There is a diffuse infiltration by abundant atypical small cells, along the cords in the red pulp, in the sinuses, and surrounding the PALS regions. The small cells are monotonous and have round or slightly irregular nuclei with moderately condensed chromatin. The cytoplasm in minimal. In addition, scattered and clusters of large pleomorphic cells are noted in red pulp, sinuses or around the white pulp. They have single round or convoluted nuclei with frequent large nucleoli. The cytoplasm is abundant and amphophilic. The sinuses in the red pulp are patent and contain many histiocytes, some of which show erythrophagocytosis. Overall, the spleen shows infiltration by two populations of tumor cells. A small cell population reveals similar morphologic and immunophenotypic features to hepatosplenic T-cell lymphoma (HSTCL). A second minor population consists of large pleomorphic cells with expression of CD30. It is possible that the large cells represent transformation from the small cells. The absence of classic sinusoidal involvement and the presence of large CD30+ tumor cells are not typical for HSTCL although the small lymphoma cells have a similar immunophenotype to that of HSTCL.