In this example, immunohistochemical studies demonstrated that the RS-like cells were positive for CD30 and CD15 and negative for CD45 (leukocyte common antigen
) and B-cell markers including CD20, PAX-5, CD10, and BCL-6.
PAX5 and TdT are also commonly seen, while expression of leukocyte common antigen
(CD45), CD34, and CD20 may show any pattern of expression from bright to negative (see Figure 3, c for a representative example).
The pleomorphic, large, epithelioid, and spindle-shaped neoplastic cells of both specimens showed a diffuse cytoplasmic positivity for vimentin and membranous expression of leukocyte common antigen
and UCHL-1 (Figure 6).
There was no reaction with antibodies directed against S100 protein and leukocyte common antigen
, while staining with the monocyte-macrophage marker CD68 was globally strongly positive in both the stromal and giant cells.
(4) In our case, we observed membranous positivity for leukocyte common antigen
in the histiocytes that infiltrated the salivary gland, which in our opinion can be regarded as additional evidence that these cells originate from bone marrow-derived monocytes or macrophages.
Lymphoepithelioma-like carcinoma tumor cells are immunoreactive to cytokeratin and epithelial membrane antigen and are negative for leukocyte common antigen
, confirming their epithelial nature.
Immunohistochemically, the cells were focally positive for vimentin; diffusely and strongly positive for immunoglobulin (Ig) A (Figure 3, A) and [Kappa] light chains (Figure 3, B); and negative for IgG, IgM, [Lambda] light chains, leukocyte common antigen
, CD20, cytokeratin, S100, HMB45, and smooth muscle antigen.
Gastric large cell lymphoma expressing cytokeratin but no leukocyte common antigen
: a diagnostic dilemma.
The tumor was also studied by means of electron microscopy and immunohistochemical stains against keratins (human cytokeratin high-molecular-weight MO630, Dakopatts A/S, Glostrup, Denmark), epithelial membrane antigen (E29, Dako), leukocyte common antigen
(2B11 +PD7/26, Dako), vimentin (V9, Dako), neuron-specific enolase (BBS/NC/VI-H14, Dako), synaptophysin (SY38, Dako), and chromogranin A (DAK-A3, Dako).
The tumor cells were focally positive for CD20 (L26) (Dako), but negative for CD45RB (leukocyte common antigen
) (Dako), epithelial membrane antigen (Dako), or other T- or B (CD79a)-cell surface markers.
T-cell-associated antigens (CD3 and CD45RO) as well as leukocyte common antigen
(CD45) were also absent.
Reactions for CD45 (leukocyte common antigen
), CD3, CD45RO (UCHL-1), and epithelial membrane antigen were negative in the cells of interest.